Electroactive Polymer Actuators, Sensors, and Devices (EAPAD) 2025

Elastocalorics is an innovative, disruptive heating and cooling technology that - due to its high energy efficiency and absolute climate friendliness - has been declared as the most promising alternative to existing vapor compression technologies by the EU Commission and the US Department of Energy. The technology is based on the exceptional heating and cooling capacity of special metals, so-called shape memory alloys made of, e.g., nickel-titanium. During simple mechanical loading and unloading of superelastic shape memory alloys, considerable amounts of latent heat are released or absorbed through phase transformations in the crystal lattice structure. This can lead to temperature differences of around 40 K already with currently available materials originally developed for biomedical applications. The lecture gives an overview of preliminary experimental investigations to identify thermodynamically optimized processes as well as the development of different demonstrator concepts as a blueprint for future heating and cooling machines.

The construction industry is a major contributor to environmental harm through carbon emissions. While there are efforts to lower emissions at the level of individual buildings, broader urban policies can unintentionally increase overall city emissions due to limited urban-scale data and complex, interconnected factors. This research presents a structured framework to develop high-resolution data on urban building stocks, paired with an advanced simulation model. The model quantifies the carbon impacts of different urban planning strategies, helping to identify optimal approaches for mitigating environmental effects. By focusing on the Chicago metropolitan area, the study validates this methodology and explores potential long-term CO2 emissions under various development scenarios. The study simulated over one million buildings and 350,000 iterations, generating a platform with tailored visualizations. Key findings highlight the significant role of building lifespans on urban carbon emissions, revealing that buildings with a 50-year lifespan produce three times more CO2 than those with an 80-year lifespan.

The conversion of yarn twist to the twist of coiling, and the reverse, is important for our high-performance artificial muscles, mechanical energy harvesters, and twist-based refrigerators. We here describe the physical basis of each of these quite different devices, the differently needed structures for performance optimization, and some of their applications. Key issues are how we can modify the fabrication method and used material in order to optimize performance for specific application needs, as well as dual needs like a yarn that can perform as a muscle, mechanical energy harvester, and an energy storage device. In many cases, there are no presently known alternative methods for achieving the performance of our yarns. For example, for harvesting mechanical energy between 2 and 120 Hz, our most recent twistron carbon nanotube harvesters have higher gravimetric peak power and average power than previously reported for any prior-art, material-based mechanical energy harvester. The last discussion will be on our recent discovery of a mandrel-free method for cheaply making high spring index muscles that provide giant muscle strokes and their use for comfort adjusting jackets.

Twisted and coiled polymer fiber actuators can provide a large work output of 2.1-2.6 kJ/kg at a constant external force. However, for realistic applications, variable external forces and periodic motion need to be considered. This paper measures the work loops of twisted and coiled polymer fiber actuators to obtain the work output per unit cycle. The paper finds for the first time that the softening property of the material due to temperature significantly deteriorates the work output. The upper limit of work output is determined by the crossover point of the work loop graph, reaching 0.39 kJ/kg in our initial studies. Deterioration of the work output is also caused by viscoelastic property. This paper further shows that a simple graphical method, that can be extended to other actuators, and can be used to estimate the crossover point and the maximum work from a stress-strain curve.

Twisted and coiled polymer actuators (TCPAs) offer the advantages of large stroke and large specific work as compared to other actuators. In this work, we develop a three-dimensional finite element model that includes the physics of the fabrication process to simulate the actuation of TCPA under generalized loading and boundary conditions. After its experimental validation, the model is used systematically to explore the key factors responsible for actuation under free and isobaric-loading conditions. This study provides insights into various factors responsible for actuation such material anisotropy in thermal expansion and elasticity, angle of twist, chirality, and actuation of composite-based TCPAs.

Deep vein thrombosis (DVT) occurs when a blood clot forms in the deep veins, typically in the lower leg. Following DVT treatment, venous damage remains, causing symptomatic chronic venous insufficiency - manifesting as severe swelling and chronic pain. Treatments include static compression stockings (20-30 mmHg) and pneumatic compression pumps (15-50 mmHg). However, these tend to have low usage due to discomfort and lack of convenience. Our solution is an active compression textile driven by twisted and coiled silver coated nylon actuators (0.6 mm coil diameter). Joule heating increases the temperature to 80 °C, generating strain (~6%, relative to stretched length with 272 g hanging mass), which translates to 19 mmHg of compression pressure when four actuators connected in parallel, arranged circumferentially are activated (0.39A, 26V) on a calf model. Next steps are to demonstrate cyclic compression in a portable device and reach the target pressure change of 30 mmHg.

The use of thin artificial muscles and soft materials will facilitate the advancement of robotics, enabling the development of robots that mimic the intricate structural characteristics observed in animal bodies. It is anticipated that this will result in superior locomotion performance, including flexible movements that emulate those of a living creature, adaptability to the environment, shock absorption, and intelligent movements based on the physical characteristics of the body. The crucial technology is a flexible material that is capable of active movement. This presentation will introduce our latest research on active flexible materials, as well as the field of deep biomimetic robotics and its medical applications.

This study presents a biomimetic approach to developing a scalable, 3D-printable phantom of a California sea lion pelvis using DICOM-standard images and the 3D image processing software Simpleware, for the purpose of veterinary blood extraction training. The model was fabricated with tissue-mimicking transparent Humimic Medical Gel and embedded with an artificial caudal vein and electroactive polymer-based sensing components to provide 'poke-point' feedback for veterinary trainees. Emphasis is placed on material characterization and matching to blubber and skeletal tissue, with compressive hysteresis stress-strain plots provided via dynamic mechanical analysis (DMA), and a preliminary attempt for real-time feedback for in vitro medical training, ultimately improving the quality of care for animal patients.

This study explores the integration of tubular ionic polymer metal composite (IPMC) actuators in minimally invasive surgery (MIS), addressing limitations in conventional surgical tools. IPMC, a smart material with low driving voltage and high bending capability, offers potential as a biologically inspired actuator in surgical robotics. A novel tubular IPMC actuator with sectored electrodes was designed and fabricated to allow precise, fast deformation suitable in the field of biomedical devices. Experimental results, based on testing at varying frequencies and voltages, reveal a trade-off between electromechanical performance and durability. Lower frequencies and voltages enhance repeatability, while higher values lead to higher displacement with faster dehydration, electrode corrosion, and a decrease in performance over time. This work highlights the importance of balancing performance factors in the development of tubular IPMC actuators for biomedical applications.

Pneumatic artificial muscles (PAMs) consist of an elastomeric bladder wrapped in a helical braid. When inflated, PAMs expand radially and contract axially, producing large axial forces. The axial and radial behavior of PAMs have been well studied. The torsional response of PAMs has not been explored before. Accurate prediction of the torsional force was desired for use in a bio-inspired, worm-like robot capable of using an auger mounted to a PAM to bore out tunnels. Modeling of the torsional response was performed using a force balance approach. Non-linear optimization was utilized to determine the material properties of the PAM to account for forces due to bladder strain. Multiple model variations were considered, such as St. Venant's torsion, bladder buckling, and asymmetrical braid loading. Torsional testing was performed to validate the model using a custom torsional testing system. Data from the tests was compared to the predicted torsional response.

In this work we developed a tensegrity-based soft robot that achieves locomotion via rolled dielectric elastomer actuators (RDEAs), i.e., fiber-like soft actuators capable of contracting along their main axis under high voltage excitation. Several sets of RDEAs connect two V-shaped rigid components to form a 2D tensegrity robot structure. By applying periodic voltages, the components oscillate, propelling the robot via angled bristles at speeds up to tens of centimeters per second. We investigate how varying voltages, frequencies, and bristle designs affect locomotion. The joint-free tensegrity structure of the system offers resilience to external forces, and sets the stage for future developments in tensegrity-based locomoting soft robots using dielectric elastomer actuators.

Facial paralysis is a highly burdening condition, resulting in a patient's inability to move his musculature on one or both sides of the mouth. The restoration of facial movement is crucial for enhancing the overall patients' quality of life. The use of DEAs is proposed as a less invasive approach for dynamic facial reanimation. This demonstration illustrates the use of DEA artificial muscles for facial reanimation with an anatomically precise skull setup and a silicone-based tissue model of human facial skin (Figure 1). The setup integrates a DEA prosthesis for smiling and blinking movement restoration. Computer vision and deep learning are used to detect the facial movements of a person using a camera, and the resulting signal is processed to control a high voltage power supply and operate the DEA prosthesis in real time.

We developed a locomoting soft-robot utilizing the high speed of silicone-based Rolled Dielectric Elastomer Actuators (RDEAs) in conjunction with tensegrity-structures. Two V-shaped rigid segments are coupled by four groups of RDEAs (Figure 1). By applying alternating voltage signals to the groups at the resonant frequency of the system, which is approximately 50 Hz, the V-shaped segments oscillate. Since each of the segments is equipped with bristle structures, which provide anisotropic friction, the robot is propelled forwards at a speed of over 200 mm/s (1.4 times its body length/s). This speed, in both absolute and relative terms, is one of the highest in the reported literature. Our work is the first exploring the combination of tensegrity structures and dielectric elastomer actuators for locomotion. In the future, we aim to extend this concept by operating the robot with an integrated power source as well as steering capabilities.

Ras Labs brings a sense of touch to robots, and has recently entered the humanoid space with a focus on humanoid hands. Soft compliant Tactile Fingertips are extremely sensitive, robust, have a wide pressure range, can communicate information about the object being handled and the grip quality, and can quickly and gently adjust the grip in real time. Tactile Fingertips (Figure 1) were developed with the goal to replicate human fingertip-like touch for well-controlled gentle grasp in both electric and pneumatic robotic grippers. Multi-point Tactile Fingertips were adapted to the Carnegie Mellon LEAP Hand, and then scaled to the human hand. Collaborative and humanoid robotics are an exciting new frontier, combining advances in robotics, artificial intelligence-machine learning (AI-ML), and material science. This sensing technology is bringing touch, human-like control and dexterity, to humanoid hands.

An energy storage device (battery) based on silicone rubber bands is demonstrated. The rubber stores mechanical energy upon stretching. Gears and an induction motor convert the stored mechanical energy into electrical power upon allowing the rubber to relax. This energy can be used to power small devices, such as light bulbs or mobile phones. The system is ideal for remote and off-grid environments. Unlike dielectric elastomer generators that depend on advanced electrode materials and complex power take-off technologies, this new silicone rubber material is easier to produce, more reliable, and highly efficient for energy storage. With a current energy density of up to 55 kWh/ton (excluding device weight and mechanical losses), silicone elastomers have the potential for further optimization to increase energy densities (per mass) beyond that of lithium-ion batteries. As a result, silicone elastomers offer a sustainable, affordable, and reliable solution, representing a new approach to energy storage.

Recent advancements in electrically tuneable optical lenses have greatly impacted applications like machine vision, microscopy, and mobile devices. Effective adaptive lenses have been demonstrated by using a variety of actuation strategies, including electrowetting effect, liquid crystal actuation, dielectrophoretic activation, piezoelectric/electrostrictive actuation, hydraulic/pneumatic driving, electromagnetic transduction, electrostatic zipping, electro-thermal activation, and dielectric elastomer actuation. Both fluid lenses and elastomeric lenses have been demonstrated, although the latter are particularly attractive, due to their superior resistance to thermal fluctuations, mechanical vibrations, and gravitational sagging. However, most technologies for controlling the focal length of elastomeric lenses have a limited focal range, owing to a limited ability to vary the lens curvature. Here we demonstrate a new, thin, entirely solid dielectric elastomer actuation-based lens that enables significant variations of focal length, from close to far distance (Figure 1).

In murky and cluttered underwater environments, an unmanned underwater vehicle (UUV) can assist divers and researchers to complete their mission goals. Using an artificial muscle driven bioinspired robot equipped with soft sensors, we demonstrate an intuitive way of controlling an UUV using a gesture recognition dive glove equipped with dielectric elastomer sensors. Sensors embedded into the glove estimate hand poses, and then translate them into commands for the UUV, which the glove communicates via an acoustic modem to a receiver. These commands are interpreted, giving the diver the capability to steer the UUV even when out of sight or in murky water where optical methods would fail.

This presentation focuses on the lightweighting of vehicle structures by means of two mechanisms. One mechanism is the functionalization of structures through the incorporation of sensors, actuators, and energy harvesting systems based on piezoelectrics and other active materials. The other revolves around advanced manufacturing to enable the integration of carbon fiber into metallic vehicle structures. We have made significant progress toward the functionalization and multi-material integration of vehicle structures through the use of ultrasonic additive manufacturing (UAM), a solid-state metal 3D printing process that allows for seamless joining, embedding, and integration of structural metals, organic polymers, shape memory materials, ceramics, electronics, and high-value components. UAM uses high-power piezoelectric transducers to weld metal foils additively, encapsulate high-value materials into metal structures, and join dissimilar materials. The research activities discussed here are conducted within the Smart Vehicle Concepts Center, a graduated NSF IUCRC that was established to accelerate the transition of advanced materials from the laboratory to the mobility industry.

Last year, vehicles transported over 11 billion tons of freight, more than $32 billion worth of goods each day, and moved people more than 3 trillion vehicle-miles. One of the U.S. Department of Energy (DOE) missions is to achieve net-zero by 2050 that requires dramatic energy efficiency and emissions improvements in vehicle and the overall transportation system. The DOE’s Vehicle Technologies Office (VTO) provides low cost, secure, and clean energy technologies to move people and goods across America. Advanced polymer composite materials are essential for boosting the fuel economy of modern automobiles while maintaining safety and performance. A 10% reduction in vehicle weight can result in a 6%-8% fuel economy improvement, since it takes less energy to accelerate a lighter object than a heavier one. Using lightweight vehicle components enabled by lightweight materials in one quarter of the U.S. fleet could save more than 5 billion gallons of fuel annually by 2030. One of the lightweight materials candidates such as advanced fiber-polymer composites in these vehicles can offset the weight of power systems such as batteries and electric motors, improving the efficiency and increasing their electric vehicles (EVs) driving range. Alternatively, the use of lightweight materials could allow for the use of a smaller and lower-cost battery while keeping the all-electric range of plug-in vehicles constant. VTO supports research, development, and deployment of efficient and sustainable highway transportation technologies that will improve fuel economy and enable America to use less petroleum. These technologies, include batteries & electrification, materials technology, mobility systems, and technology integration will increase Americans’ mobility and energy security, while lowering costs and reducing environmental impacts. VTO collaborates with industry, academia, and national laboratories to develop and deploy advanced vehicle technologies. Such technologies can lead to a game changer in setting the foundation for clean, efficient, sustainable, and cost-competitive vehicles. This plenary presentation will provide a vision and overview of science and innovation of the ongoing Composites Core Program and the VTO composites strategy and portfolio that have smart monitoring components associated within the EVs, as well as share the information of DOE funding opportunities. New research utilizing advanced fiber-polymer composites to reduce manufacturing cost and weight of EVs with added multi-functionalities to reduce embodied energy of vehicle components, reduce battery volume through increased vehicle efficiency as well as decrease greenhouse gas (GHG) emissions will be discussed. Such lightweighting and multifunctional composite materials and structures technologies with electric and autonomous vehicles (AVs) health management could have a great potential to transform the current EV/AV platform.

Research on electrically tuneable optical lenses for various applications, including machine vision, microscopy and mobile devices, has experienced significant growth in recent decades. Effective adaptive lenses have been demonstrated by using a variety of actuation strategies, including electrowetting effect, liquid crystal actuation, dielectrophoretic activation, piezoelectric/electrostrictive actuation, hydraulic/pneumatic driving, electromagnetic transduction, electrostatic zipping, electro-thermal activation, and dielectric elastomer actuation. Those used to tune the focal length of elastomeric lenses critically limit the achievable focal range, owing to a limited ability to vary the lens curvature. This presentation will provide an overview of the state of the art and will describe ongoing developments by the authors about a new type of dielectric elastomer actuation-based tuneable lens, capable of a large focal range.

The Live Mirror consortium, supported by the Horizon European Innovation Council, is spearheading the development of an innovative technology for a new lightweight, hybrid, and self-correcting mirror. This cutting-edge mirror relies on three critical elements: (1) precise processes for shaping fire-polished sheet glass; (2) a dynamic hybrid structure using 3D-printed flexible electrodes and electroactive polymer force actuators to support the mirror and correct its deformation in response to thermal changes, gravity, and wind loads and (3) a metrology & calibration multi-sensing in real-time closed-loop control. These smart structure advancements will yield cost-effective, lightweight, integrated optoelectronic systems and demonstrate new remote sensing capabilities from terrestrial and space-based platforms. We will provide an update on the status of the research and development of the Live Mirror technology.

A variety of display technologies can be employed to achieve reproduction and color change as organic light-emitting diodes and liquid crystal displays, which are based on light emission. In contrast, non-emissive technologies utilize selective absorption and diffusion of incident light to generate color. A variety of non-emissive technologies are being developed, including cholesteric liquid crystals, electrowetting, and electrophoretic materials. These technologies offer the advantage of requiring less energy than emissive ones. Electrochromic materials, which include inorganic oxides, organic molecules and polymers, can undergo color changes in response to an electrical stimulus. These materials can be utilized in the development of a color reproduction system. We present here the design of a device with an innovative superimposed architecture that is capable of reproducing a wide range of colors. To achieve this, we have stacked three pixels based on three electrochromic polymers with the three primary cyan, magenta, and yellow (CMY) colors. We propose and discuss three new architectures in which the three CMY pixels are superimposed in a single device.

Polymeric ferroelectrics are unique for their high pliability, easy fabrication into complicated shapes, and mechanical robustness along with a polar active nature. In the past few years, polymer ferroelectrics have exhibited marked improvements in the electromechanical coupling efficiency, electrostrictive strain, electrocaloric heat-pumping capability. For the first time, the piezoelectric and electromechanical coupling factors of fluorinated alkyne-modified relaxor ferroelectric tetrapolymers have surpassed those of PZT piezoceramics. Additionally, the advances in ferroelectric-based electrocaloric polymers have led to large electrocaloric cooling under ultralow electric fields. Exploiting the high electromechanical and electrocaloric performance of this new class of ferroelectric polymers, demonstrated recently a self-actuated electrocaloric heat pump. This talk will present recent advancements in the ferroelectric polymers and their device applications.

Electroactive polymers (EAPs) are promising for mobile, portable, and soft robotics, though their potential for larger-scale applications and advanced environments remains under exploration. This presentation reviews projects pushing EAPs beyond conventional uses, focusing first on dielectric elastomers (DEs), which have been applied to large-scale energy harvesting and multi-sensory user interfaces, leveraging the DEs’ dynamic properties. The focus then shifts to fluid gap transducers (FGTs), a newer EAP technology addressing DE limitations. The presentation explores FGTs’ potential in space robotics, using vacuum-based liquid-free dielectric gaps.

In recent years, research on self-healing mechanisms in lithium-ion batteries aims to extend the lifetime of such batteries or to repair them in case of a decreasing state of health (SOH) directly in the used system. These self-healing mechanisms work usually with an external trigger such as pressure or temperature. The authors present a 0.3 mm thin and 100 mm x 60 mm wide HASEL (hydraulically amplified self-healing electrostatic) actuator, which is tested as a self-healing pressure trigger device placed in a special environment with the lithium-ion battery. The maximum generated pressure during lab tests is up to 70 kPa at 140 kV/mm electric field strength. A continuous variation of that pressure depending on the applied electric field strength is possible, which offers also the possibility for a dynamic interaction with the battery in its operation.

Electrohydraulic soft actuators have attracted considerable research interest due to their promising features, such as large actuation strokes and fast response speeds. In this study, aimed at further improving performance, we report on a preliminary investigation of a multifunctional electrohydraulic soft actuator. Unlike other soft actuators of the same type, our actuator employs a non-uniform electrode shape, enabling both actuation and electroadhesion as additional functionality. Experimental results showed that the fabricated actuators exhibit large actuation strokes while simultaneously generating electroadhesion, successfully validating the proposed actuator concept.

The decline in ocean health requires better data collection on marine environments, but traditional unmanned underwater vehicles (UUVs) that rely on thrusters face significant challenges, such as inefficiency, noise pollution, limited maneuverability, and potential damage to delicate ecosystems. To overcome these issues, biomimetic solutions are being explored, with HASEL (Hydraulically Amplified Self-healing Electrostatic) actuators emerging as a promising alternative. These actuators enable more natural and efficient movement underwater. This work proposes the integration of HASEL actuators into a biomimetic UUV design, initially focusing on a caudal swimmer mimicking tail propulsion in marine animals, with future plans to develop a rajiform swimming mechanism to replicate the undulating motion of rays. By addressing key challenges like waterproofing and actuator durability, this design aims to improve UUV efficiency, maneuverability, and environmental compatibility, ultimately enhancing our ability to monitor and protect marine ecosystems.

Electroactive polymers (EAP) have significant potential for space applications due to their reliance on lightweight materials, flexibility, large strokes and low costs. However, the harsh environment has hindered their applicability through strict materials limitations, performance and reliability thresholds. Recent advances, such as the electrostatic multilayer systems, and in particular, electrostatic bellow muscle (EBM) and the electro-ribbon, offer new opportunities by employing electrostatic zipping principles to induce deformations in soft polymeric structures. Herein, we present a new electrostatic actuation paradigm for space applications with large materials and design freedom, by demonstrating the EBM actuator in high vacuum environments. Substituting the bulk dielectric material with a vacuum gap leads to significant benefits over any other EAP through lower mass, higher actuation bandwidth and cost efficiency. We showcase this technology in a gripper application.

Even though many dielectric elastomer (DE) soft robot prototypes have been presented in the literature, most of current studies only focus on the practical demonstration of the device principle, without performing systematic performance optimization or intelligent control. In case of single degree-of-freedom (DoF) DE actuators, it has been demonstrated how the synergistic integration of model-based bi-stable design and self-sensing control principles generates systems capable of performance that are not possible by focusing on one perspective only. The generalization of such approaches to complex DE soft robots, however, is still unexplored in the literature. Leveraging a model-based perspective, this talk will present how bi-stable design and self-sensing control principles can be systematically transferred from simple DE actuators to multi-DoF DE soft robots. Aspects related to model-based design, performance optimization, motion control, and self-sensing will be covered, using multi-DoF DE soft manipulators as experimental demonstration platforms.

Dielectric elastomer actuators (DEAs) mimic muscle function and are ideal for soft robotics, offering rapid and precise electromechanical control. Through a high-voltage supply, we developed a semiconductor-like device, DES, and DE-Electronic Networks capable of memory and computation, enabling integration with soft robots to replace rigid control systems. Our peristaltic robot design uses the expansion and contraction of DEA for motion, controlled via a DE network incorporating DE oscillators (DEO). A complex DE network with two DEOs and a multiplexer allows advanced functions like steering by adjusting oscillation frequencies. Inkjet printing technology are also used to enhances precision and circuit stability. This project demonstrates that combining flexible robots with flexible circuits can make future soft robots more complex and intelligent.

Dielectric elastomer actuators (DEAs) offer lightweight, resilient, cheap, and fast-response capabilities ideal for soft robotics applications. The goal of DEA robots is to interact with their environment in a new save bio-inspired way. DEAs are limited by small actuation and force output but recent studies show that stacking multiple layers of DEAs can increase the actuation force and deformation. In this study, we propose a novel design for a soft robotic hand gripper with multilayer DEAs and bones structures that mimics a human hand. The soft robot was fabricated using multiple layers of DEAs and can bend like a human hand in order to grasp objects. This novel design will autonomously fulfil basic tasks, such as grasping, and utilize effects such as electrostriction to interact with the surrounding environment. Software simulations with Abaqus have been performed to simulate the optimal parameters to increase bending and force of the fingers.

Human grasp is simultaneously gentle yet firm, provides a large amount of tactile touch information, and is intuitive. Ras Labs produces a class of electroactive polymer (EAP) based materials and actuators that sense pressure from gentle touch to high impact and attenuate force. The primary objective of the research and development of this technology towards sensing was to provide for tactile touch sensing systems that are human fingertip-like in how they feel, including the ability to detect very light pressures. This was accomplished, routinely down to 0.05 N, and in its maximum sensitivity mode, even to 0.005 N. These Tactile Fingertips, though extremely sensitive, also had a wide pressure range, up to 40 N (and more). Algorithms, artificial intelligence (AI), and machine learning (ML) were integrated into these sensors for object identification along with the analysis of good grip (position, grip force, angle, any slip or wobble) and immediate correction. This tactile fingertip system is remarkedly like the human fingertip. This sensing technology is entering the humanoid space with a focus on bringing touch, thus human-like control and dexterity, to humanoid hands.

This study presents the development and experimental validation of an artificial urinary sphincter (AUS) using dielectric elastomer actuators (DEAs) for treating urinary incontinence (UI). Traditional AUS devices are complex and often male-specific. DEAs offer flexibility, lower mechanical demands, and broader applicability. A DEA-based AUS was designed and experimentally tested under physiological conditions. The electrically controlled system allows precise modulation of urethral opening based on real-time bladder pressure. Results demonstrated the DEA's ability to adjust dynamically, maintaining structural integrity across repeated cycles. These findings support the potential of DEAs as a promising alternative to conventional AUS devices.

The use of plasticized P(VDF-TrFE-CFE), a relaxor ferroelectric polymer, has shown major improvements over the past few years. Dedicated to telescopes’ active optics actuators for the Live-Mirror project, the optimization of the plasticizer interaction with the polymer matrix for duplicated strains is investigated here. The adaptation of the terpolymer composition displays drastic increases in electromechanical properties, leading up to S33 of 2.9% at 20MV/m. The electrical breakdown strength is furtherly increased with purified solvents and thinner 4D-printed layers. In combination with soft electrodes, which impact on the actuator structure is visualized through COMSOL Multiphysics simulations, the multilayer-actuator structure will duplicate the mirror's morphing to match the target displacement of several microns.

In the framework of a multidisciplinary project focused on the developement of soft generators for the road infrastructures, involving two laboratories of Electrical and Materials Engineering, a preliminary study concerning the energy convertion of passing véhicules through the use of dielectric elastomer generators (DEG) is presented. The practical limits related to the specific application, the excitation conditions, the trade-off concerning the active materials characteristics, and the structural architecture design have been taken into consideration for the choose of technological solutions, material engineering, and device dimensioning. The synthesis of soft composite materials based on the use of liquid silicone rubber matrix and organo-inorganic fillers, their electrical and mechanical characterization and their integration in a multilayer architecture obtained through a simple and low-cost process are presented. An interdigitated mechanical structure is designed to ensure a relevant electromechanical conversion in a limited space, allowing the integration of such a device, and also ensuring its robustness, in the extreme conditions that characterize the road environment.

Bi-stable electrostatic energy generators offer a promising alternative to traditional mono-stable systems for harvesting low-frequency natural energy sources like wind and waves. These systems achieve large displacements through snap-through transitions between two stable states, enabling effective operation over a broad range of frequencies. In this paper, we analyze and optimize a representative electrostatic bi-stable energy harvester for a target real-world environment, by tuning parameters such as damping, inertia, and the double-well potential to maximize its converted energy. Dynamic simulations are used to evaluate performance under realistic conditions. Finally, potential designs using dielectric elastomer membranes and nonlinear biasing springs are explored, focusing on real-world applications.

When a dielectric elastomer (DE) membrane is used as a deformation sensor, changes in its electrical capacitance are used to reconstruct the transducer average strain. At sufficiently high frequencies, however, a DE behaves rather as a RC transmission line. By detecting changes in the shape of the resulting DE frequency response, one can implement novel sensing paradigms in which a single-port impedance measurement allows estimating a distributed deformation pattern along the membrane. In this work, we present a physics-based model which describes how port electrical impedance of a DE membrane depends on several parameters, i.e., applied strain field, electrode material (i.e., resistivity), and geometry (i.e., electrode width, thickness, and pattern). Extended simulation studies show how different choices of material parameters map the same strain profile into different impedances behaviors, making it possible to effectively tune the distributed sensing characteristics.

Flextensional transducers are widely used as low-frequency projectors, and their characteristics can be applied to develop hydrophones with broader receiving bandwidths and higher sensitivity in low-frequency ranges compared to conventional products. We designed flextensional hydrophones across all classes and compared their acoustic receiving performance to identify the most suitable class for a low-frequency broadband hydrophone. Basic models were constructed for each class, and the effects of various structural parameters on acoustic receiving characteristics were analyzed by means of the finite element method. Using these results, we optimized the structure of each class to maximize receiving bandwidth while maintaining a certain level of receiving voltage sensitivity. The comparison of designed performances highlighted the class IV flextensional hydrophone as the most promising, offering the widest receiving fractional bandwidth and highest sensitivity. Its superiority was further confirmed by comparing its performance to representative commercial hydrophones.

Flexible conductive materials have gained increasing interest for life style products such as smartphones and smart textiles. A special group amongst them are stretchable electronics that cannot only withstand bending forces but can also deform elastically under strain. However, these characteristics also come with challenges. The electronic circuits used for signal processing are made of non-elastic materials and due to the different Youngs modules the connections lead to noise during mechanical loads up to system failure. In this study we assess different printed silicone based conductive structures under bending and uniaxial strain. Thereby, we characterize capacitive and resistive phenomena in loading scenarios. Furthermore, we use varying methods for electrical connection: conductive glue, adhesive aluminum tape and sewing, and investigate the durability and effects on the electrical signals. Amongst the tested specimen the glued cables on particle filled silicone showed the most stable connection.

Dielectric elastomer actuators (DEAs) necessitate stretch- able electrodes that show mechanical compliance and sus- tain conductivity even under stretching. A percolative net- work of silver nanowires (AgNWs) as an ultrathin film formed on the elastomer meets all these requirements as stretchable electrodes. However, AgNWs are prone to thermal degradation due to resistive heating caused by applied electrical current. This work introduces a hybrid stretchable electrode of AgNWs coated by graphene nanoplatelets (GNPs) to produce more resilient and durable DEAs. GNPs added to pre-formed AgNW structures act as a protective layer, mitigating localized heating at NW junctions and eventually preventing DEA failure. The hybrid electrodes show a sheet resistance as low as 9 Ω/sq and the electro-mechanical strain as high as 56.5% at electric field of 45 V/μm when inte- grated into the DEAs. The AgNW/graphene DEAs also show high endurance withstanding an applied electric field up to 70 V/μm without failure. This work showcases advantages of a rationally selected hybrid materials that produce more resilient DEAs.

Soft actuators, such as dielectric elastomer actuators (DEAs), are often optimized with a focus on achieving maximum deformation and flexibility. However, for practical use and integration into various applications, the generated force and achieved work is also crucial parameter. Determining this force can vary in difficulty depending on the DEA design and the direction of displacement. For instance, for movements in plane along one or two axis like for equibiaxial dielectric elastomer actuators, the analysis of force is often not included. In this work, we present thus a home-build setup for determining the force of planar DEAs in uniaxial, biaxial and equibiaxial direction. Using this setup, the influence of different parameters like pre-stretch on the generated force are investigated and compared with the influence on the displacement. Understanding these influences allows for future DEA designs that balance both, force and strain, rather than focusing solely on maximum deformation.

Recent advancements in electrostatic transducers (ESTs) have enabled their use on larger scales by employing multilayer structures made of flexible polymeric dielectrics and electordes. We introduce here novel manufacturing method for ESTs featuring flexible conductive electrodes. Our approach involves directly forming laser-induced graphene (LIG) on polyimide (PI) film substrates. This process uses laser pyrolysis to create a porous, flexible, and conductive carbon structure within the PI substrate, eliminating the need for masks or additional components. The method is solvent-free, cost-effective, and highly customizable. We show various EST demonstrators, including an artificial muscle, an electroadhesive device with submillimeter electrode widths, and an electrostatic clutch. A comparative analysis highlights the benefits of our method over conventional printing and metal deposition techniques, demonstrating its versatility and effectiveness for large-scale applications.

Leg orthotic devices are often used to support and help rehabilitate individuals who have lost some functionality in their leg muscles, such as seniors, veterans, or other individuals who have been injured or suffer from diseases like myopathy. Dielectric elastomer actuators (DEAs) are soft actuation materials with promising applications in robotics and biomedical devices because of being compact, lightweight, and resilient. In this paper, a tubular actuator is developed with DEs and conductive fabric, and tested for orthotic applications. The novel orthotic technology developed in this paper is capable of providing the same support and rehabilitation to muscles as traditional leg braces while being lighter/less bulky, more comfortable by using conductive fabric, and able to adjust size as one’s limb grows by using DEA. A prototype of this device is developed and characterized. A rolled DEA strip was actuated over an artificial limb by a periodic signal while the amount of the movement is observed. The experimental results validated the feasibility of future development of a dielectric elastomer-based orthotic leg brace.

Haptic technology improves digital interactions by simulating the sense of touch through tactile feedback or vibrations, creating more natural and responsive experiences. However, developing soft piezoelectric actuators for haptic feedback poses challenges, particularly in balancing mechanical flexibility with strong piezoelectric properties. This study addresses these issues by introducing a dual-layer flexible film made of polyvinylidene fluoride-co-trifluoroethylene (P(VDF-TrFE)) and barium titanate (BaTiO3, BTO). Scanning electron microscope (SEM) observation, alongside tests on piezoelectric properties, and electric field response, demonstrated that the dual-layer design outperforms traditional piezoelectric films, especially in the 31-direction commonly used in haptic systems. This approach provides a promising solution to enhance the efficiency and flexibility of piezoelectric actuators in haptic technology, opening up possibilities for improved haptic devices.

Carbon particle-filled elastomers are widely studied for applications like dielectric elastomer actuators and resistive stretchable sensors. Solvents are commonly used to reduce the viscosity of uncured elastomer mixtures in manufacturing processes, but their effect on bulk material resistivity remains underexplored. It is often assumed that solvents fully evaporate during curing. This study addresses these knowledge gaps by tracking the resistance and solvent evaporation of carbon-filled silicones during curing, considering factors such as curing temperature, sample thickness, and solvent type. Results show significant differences in evaporation rates and resistivity depending on the solvent. Similarly, the piezoresistive effect of the materials also differs, which makes the type and existence of solvents an important parameter to consider for manufacturing conductive elastomers.

In this paper, we present the design of a fully soft, flexible, and stretchable tactile sensor array that can be produced using low-cost materials and widely available devices. It has low requirements for circuitry and is free of ghost signals. Due to its mechanical compliance, the sensor is stretchable, allowing it to conform to irregular surfaces and be customized in shape, spatial resolution, and detection thresholds. The sensor's measurement and communication modules consist of two stacked PCBs, each measuring only 35 x 25 mm. The communication modules can be replaced as needed, with options including USB or a 24V 4-PIN connector.

The development of novel elastomer materials with advanced electrical and mechanical properties is of significant importance to improving the performance of dielectric elastomer actuators (DEAs). Actuator materials are commonly evaluated by the fabrication of circular DEAs, which consist of an equi-biaxially pre-stretched dielectric film fixed to a rigid frame. On each side of the film, opposing circular electrodes with identical radii are positioned centrally. Due to this set-up, the electrode size relative to the carrier frame’s dimension has an impact on actuator strain and displacement. In this study digital image correlation (DIC) is used to investigate the effect of electrode coverage on the deformation of circular DEAs. In contrast to conventional optical strain measurements, which record only the global electrode strain, here DIC is utilized to quantify local strains across the entire actuator region, including both active and passive areas. The non-uniform strain state in the passive area was visualized and exhibits increasingly negative strain values with increasing electrode coverage. The measurement results were compared to simulation results of a simplified model.

Dielectric elastomer actuators (DEAs) are smart materials known for their softness, stretchability, and energy efficiency, composed of a dielectric membrane and conductive electrodes. When high voltage is applied, they deform mechanically, making them ideal for high-voltage switching applications, such as Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs). DEAs offer advantages in terms of low-cost manufacturing, elasticity, and energy efficiency, addressing the limitations of traditional high-voltage switches like size and energy loss. This work focuses on designing a DEA-based MOSFET using silicone and carbon black electrodes to enhance voltage ratings and improve reliability in power electronics applications.

Dielectric elastomers (DE) consist of highly deformable polymer films sandwiched between flexible electrodes, able to function as electrostatic actuators. This work introduces an array of negative-stiffness biasing mechanisms based on thermoplastic polymers, to enhance the stroke and flexibility of distributed DE actuators. Unlike traditional systems using metal beams or silicone-based domes, this approach reduces stress and hysteresis, making it suitable for soft mechatronic devices. By integrating multiple DE actuators on a shared membrane, a cooperative actuator array is formed. Experimental results validate the performance of the multidimensional biasing mechanism, offering design and fabrication guidelines for future DE-based cooperative systems.

Dielectric elastomers (DE) are electroactive polymers with multifunctional properties such as actuation, sensing, and energy harvesting. We present the application of complex DE-circuitry to combine and intrinsically control multiple unit cells, simulated using SIMULINK. By integrating different DE components, we simulated networks capable of switching between predefined actuation patterns. The model accurately inverted the square wave pulse input voltage at each stage, replicating the delayed feedback of the DE switch. This approach can be extended to model more complex systems, validated through experimentation. It establishes the foundation for advanced multi-actuator systems in soft robotics and beyond, offering intelligent solutions for various challenges.

This study investigates the novel application of polyvinyl chloride (PVC) gel in the Electrohydraulic Actuator Powered by Induced Interfacial Charges (EPIC) actuators as varifocal lenses. PVC gels are dielectric elastomer actuators known for their actuation mechanism known as anodophilic creep, the asymmetric tendency to deform towards the anode surface. The EPIC actuator is a novel application of PVC gels that places dielectric fluid between the gel and anode to produce electrohydraulic actuation. The concentric actuation force pushes inward, causing a change in surface geometry.

Our oceans and streams, while supplying us with valuable resources, are overused and understudied. Underwater robots, whether tethered or autonomous, permit us to monitor them more closely. Often looking like little black submarines, underwater robots fail to combine the maneuverability, efficiency and stealth of ocean creatures. There currently is not a robust and affordable set of sensors able to withstand the aquatic environment and its challenges, such as pressure and salinity, which can be adapted to the requirements of each fish robots’ missions. Yet, in the complex three-dimensional navigation space of water redundant input is necessary for active learning controls. Here we show three electroactive polymer sensors which are robust, impervious to pressure and add significantly to the range of engineering capabilities available for fish robots. we have developed solid-state bioinspired sensors: two stretch sensitive parallel plate and one fringing field type capable of detecting flow angles and speeds, cross body flows indicating rolling motions and feedback regarding propulsion on maneuvering fins; we have made dumb fins smart.

IPMC sensors generate a small voltage for the applied deformation, but the response of the sensor voltage is strongly dependent on humidity. Zhu's multi-physics model is an appropriate and promising physics model that can explain the humidity dependence, as it takes into account the dynamics of water inside the IPMC sensor. The authors have analytically derived the voltage response of Zhu's model and obtained its exact solution as an irrational transfer function. However, its physical interpretation and the method for determining the time response have not been fully clarified. This paper shows that using numerically complex-curve fitting the exact irrational transfer function can be approximated by a simple first-order rational transfer function. Furthermore, it is found that the maximum and steady-state values of the step response, as well as the presence or absence of relaxation, can be accounted for using only two parameters.

A novel energy storage solution that uses silicone rubbers is presented. Instead of relying on chemical reactions or using dielectric elastomers (DEs), the novel material stores high amounts of energy through manual stretching. The stored mechanical energy can then be efficiently converted into electricity through a simple internal mechanism. This novel solution offers a sustainable, portable, and reliable alternative to traditional batteries, such as lithium-ion batteries (LIBs).

Coiled nylon 6,6 actuators are compact (600-µm diameter), have reversible contractions between 5-20%+, and exhibit a work density 100x greater than that of human muscle. This study investigates the effect of post-anneal stretching of coiled nylon actuators on compression pressure in Nomex-based prototypes designed for compression therapy. Coiled nylon actuators were integrated into three prototypes, each with actuators stretched by 14%, 28%, and 42%. The prototypes were tested on solid and silicone calf models to assess pressure generation. Results showed that a 14% stretch provided consistent compression, while higher stretches led to reduced performance or mechanical failure. These findings contribute to the development of actuator-integrated compression textiles.

Fully soft and stretchable sensors are desirable for wearable devices because of their high conformability to human skin, key to providing comfort and untethered user experiences. However, mostly targeting uni-axial stress sensing, few of these sensors have demonstrated design flexibility, manufacturing scalability, and multi-modality sensing. To address these challenges, we present a 3D-printed soft stretchable multi-modality capacitive sensor architecture, leveraging Direct Ink Writing (DIW) technology. DIW's versatility in material compatibility, multi-material printing capability, and ease of setup facilitate the precise deposition of silicone rubber ink for the sensor body and silver paste (JY12, Shanghai Julong) for electrodes, enabling complex sensor and electrode geometries, tailored to specific use cases. Our sensors demonstrate the ability to capture normal/shear stresses and proximity, which can potentially be deployed at diverse human body locations for advanced sensing applications.

Traditionally, textiles have been passive, but new demands call for smart textiles—like generating energy or sensing pressure. To meet this need, researchers are exploring how to incorporate these capabilities into existing fabric production methods. Piezoelectric polymers, such as polyvinylidene fluoride (PVDF) and its copolymers, are popular candidates for constructing such smart textiles. These piezoelectric fibers, which can generate electricity from pressure, have been mostly produced by electrospinning. While effective in enhancing the fibers' properties, electrospinning is costly and inefficient. This study investigates a more economical and scalable alternative—wet spinning of poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) with BaTiO3 fillers. We examined how different factors like drawing ratios, post-treatments, and BaTiO3 concentrations affect the fibers' performance. Our results reveal that the wet-spun fibers can produce around 10 V with a gentle finger touch and maintain their functionality after 20 wash cycles. This durability and efficiency highlight their potential for smart textile applications for harvesting energy or functioning as pressure sensor.

Soft capacitive sensors offer an approach for enhancing real-time measurements of both normal and shear stresses. We have created a ‘smart’ roller. It is a cylindrical capacitive sensor array designed for automated fiber placement (AFP) machines, widely used in laying down carbon fibers to create composite parts for aerospace and automotive applications. Available in two variants, the smart roller accommodates distinct measurement needs: one model features 4 x 13 sensing units for normal stress, while the other employs 4 x 7 sensing units for three-axis stress measurement. Both variants incorporate Bluetooth Low Energy (BLE) technology for wireless data transmission.

Electroadhesion has been thus extensively used for robotic gripping, locomotion, wearables, haptics, and medical implants, enhancing humans, machines, and human-machine interactions. Electroadhesion, induced by an electric field, is the electrostatic attraction between two surfaces, and can be configured into parallel, hairy, and coplanar structures. There is little research on the investigation into the scaling effect of electroadhesives. Here we present a finite element analysis, based on COMSOL Multiphysics, of how different scales effect the adhesive performance of parallel, coplanar, and hairy electroadhesives. We find some interesting simulation results that were preliminarily validated by some experimental results, and we hope that these findings can be useful insights for EA structural designs.

Embedded sensors enable real-time monitoring of mechanical parameters within materials and structures. To minimize the impact on structural performance due to embedding the device, minimal sensor size and quantity are preferred. Additionally, improving bonding between the embedded sensor and the monitored object, without the use of additional adhesives, is essential for accurate measurement. This paper investigates the performance of a miniaturized multiaxial sensor produced via two-photon polymerization (2PP), which offers high precision in fabricating microstructures to address these challenges. The sensor features star-shaped microchannels aligned with the geometrical axes, filled with electrodes for signal detection. Adhesive microstructures are patterned onto the sensor surface to increase the bonding surface area, resulting in enhanced attachment between the sensor and the monitored specimen during embedding. This research advances the development of miniaturized multiaxial sensors for real-time strain monitoring, as well as enhances the structural integrity and reliability of embedded sensors in mechanical and aerospace applications.

Real-time monitoring of critical infrastructure in extreme environments—such as high temperatures, radiation exposure, and space constraints—requires highly durable sensors capable of operating reliably throughout the structure's service life. Rapid decision-making is also essential for implementing early warning systems to prevent failures. While structural health monitoring techniques, such as acoustic emission and guided wave ultrasonics, are well-established in conventional settings, their performance is limited under the extreme conditions found in nuclear reactors and space structures. These environments require innovative approaches to sensor development, digital modeling, and data processing. This talk will present the latest advancements in thin-film sensors designed for harsh environments and their integration into digital models, offering a new paradigm for sensor durability and data-driven monitoring.

Wearable haptic feedback systems are designed to prioritize user comfort while delivering diverse feedback patterns for immersive interaction in virtual and augmented reality environments. In pursuit of these objectives, a novel multimodal wearable haptic auxetic fabric (WHAF) has been developed, utilizing shape-memory alloy wires structured into an auxetic design. This advanced configuration allows the fabric to expand and contract in three dimensions, providing superior adaptability to various body shapes and sizes. Additionally, the fabric is coated with a microscale layer of Parylene, which creates electrically distinct zones that enable localized actuation, allowing for the conveyance of complex spatiotemporal tactile feedback. Depending on the area of the body where the WHAF is applied, it delivers either cutaneous or kinesthetic feedback, enhancing its functionality as a multimodal interface. When worn on the forearm, for example, it intuitively provides spatiotemporal information for hands-free navigation or teleoperation in virtual environments. When applied to the elbow, it aids users in achieving specific movements, such as guided elbow flexion, functioning akin to a personalized exercise assistant.

This contribution introduces a skin-like haptic device to replicate real-world tactile sensations. The wearable haptic artificial muscle skin is based on multilayer dielectric elastomer actuators (DEA) that achieve significant out-of-plane deformation in a fully soft, millimeter-scale footprint. The design maintains comfort and wearability while providing complex tactile feedback with high perception accuracy. We further demonstrate that the devices can be integrated into extended reality systems, freeing hands for dexterous interactions and enhancing immersion.

We report a compliant haptic interface with 6 inflatable 8 mm diameter bubble shaped bumps that the user explores with their finger. One single air supply controls 6 bubbles by using integrated electrostatic valves (ESValves) to independently lock each bumps in the up or down position. Applying a high voltage to the electrodes for a given bubble generates an electrostatic force that closes off the air channel at the entrance to only that bubble, enabling independent control over the inflation and deflation of individual bubbles. In comparison to previous HAXELs (Hydraulically Amplified Taxels) from our lab, this design achieves a 3x higher fill factor of 60%, but requires an air supply. The soft, thin structure allows for integration on curved surfaces and scalability for diverse applications.

This study explores the integration of dielectric elastomer actuators (DEA) onto textiles for wearable applications, focusing on creating a flexible, tactile feedback element. The textile serves as both a structural support and a biasing mechanism for the DEA, eliminating the need for pre-loading structures. We propose a model-based design to optimize actuator performance based on different geometries and textile pre-stretches. We then present an experimental characterization of the DEA-textile element in terms of force and stroke outputs, and compare the results with human sensory thresholds.

Haptic interfaces with the capabilities of both detecting and generating mechanical stimulation have been the focus of attention for decades. Although significant progress has been made in the actuating materials and sensing materials, their integration remains a challenge. In this work, PVC gel active electronic skin (PVC gel AE-skin) with both actuating and sensing functions was developed, through designing surface array structures. Further, the actuation performance and piezo-resistive sensing performance were characterized and analyzed from the perspectives of structural mechanics, Maxwell surface tension balance and energy conversion, thereby an equivalent circuit prediction model and a multi-physics simulation model were conducted. As the results indicate, the conical array structure is the best candidate for the integrated design of PVC gel AE-skin. Finally, a portable tactile interface with braille reading and writing functions was designed based on PVC gel AE-skin. It will not only highlight PVC gel’s advantages in integration of sensing and actuating, but also inspire more tactile interaction technologies to serve people.

It is difficult to get wearable and stretchable EAP sensing systems to market. Along with the normal product development challenges, these systems are highly coupled resulting in the need for iterative co-design alongside the garment, electronics, and machine learning stacks. My talk will cover 17 years of experience fighting with this complexity as we successfully brought EAP technology out of the lab and into customer hands. I will cover the full journey, from early research, to launching a stretchable sensor business, and then finally our own product - a motion capture glove used in the content creation and XR industries.

Whenever something moves in the human body, our muscles do the work. However, while today it is part of everyday clinical practice to replace joints and bones with artificial parts, reconstruction medicine still has great difficulties finding a suitable replacement for damaged or destroyed muscles. There is one muscle in particular whose function is vital and is the subject of several studies, but without convincing results: the heart. Other muscles of the body actually share mechanical similarities with the heart, including the sphincter muscle, which, if damaged, can cause urinary incontinence. Facial muscles also share such similarities and must be replaced after an accident or injury. Although these muscles do not play a vital role in the body, they remain extremely important for patients’ quality of life, for example a well-functioning sphincter muscle is critical in order to avoid unpleasant side effects such as needing to wear diapers. The parallels between muscle types could allow the development of universal electromechanical multifunctional actuators. Within the new Center for Artificial Muscles, EPFL, in cooperation with its partners in heart surgery, face reconstruction and urology - University of Bern and Reconstructive Medicine - University of Zürich, aims to become the world’s leading reference for the development and clinical transfer of a brand-new technological approach for artificial muscles in the human body. The proposed keynote intends to show some examples realized in this new center.

This project introduces a novel wearable device: a waistband equipped with an array of low-cost piezoresistive sensors, made of carbon black and commercially available stretchable wound dressing materials. Optimally positioned around the waist, these sensors detect variations in strain caused by movements of the pelvis and hips. As such, the device is capable of monitoring changes in resistance to accurately identify a variety of activities, including walking and running, as well as distinguishing between movements of the legs. This poster outlines the current progress in the development of this technology, highlighting its potential applications in activity and posture monitoring.

This paper presents a new approach to integrating superelastic shape memory alloy (SMA) thin-film electrodes into dielectric elastomer actuators (DEAs). Using TiNiCuCo thin-film electrodes improves conductivity and enables large deformations, despite the samples used being originally designed for flexible electronics. Electro-mechanical testing validates the performance of the hybrid SMA-DEA system and demonstrating its potential for smart self-sensing. Future work aims to optimize the structure and further miniaturize the system for advanced applications.

Dielectric elastomer-based minimum energy structures (DEMES) represents a complex 3-D equilibrium configuration characterized by the minimum energy state of the system. To demonstrate this underlying mechanics of DEMES, we present a prototype of a dragonfly-inspired actuator. Both numerical simulation and experimental techniques are implemented to study the performance and behavior of the proposed actuator. The proposed DEMES-based dragonfly-inspired actuators can be implemented effectively in various futuristic applications. Their adaptability makes them ideal for micro-aircraft, adaptive aircraft wings, and even space exploration. The actuators' precision and responsiveness could potentially be used in biomedical devices, haptic feedback systems, and environmental sensors. Moreover, their ability to function in complex environments makes them a valuable tool for hazardous exploration, offering broad perspectives for innovation in robotics, aerospace, and medical technology.

WACKER’s NEXIPAL® is the next step in the value chain of EAP based transducers (sensors and actuators) based on silicone elastomers: electrically conductive and compliant electrodes are printed in a digital process on ELASTOSIL® Film, a thin and precise film consisting of crosslinked silicone rubber. Wacker has developed a scalable roll-to-roll process including in-line process controls to produce alternating layers of dielectric and conductive material on each other to form functional and manageable semi-finished goods. The production process for EAP is taking place in a clean room and allows the formation of different layer thicknesses in the range of20 µm to 400 µmof dielectric layer. All materials and processes have been developed by Wacker and will be produced in their own production facilities in Burghausen, Germany. With regard to an industrial production of electroactive polymer transducer, this step enables the development of a plurality of products.

Due to the rising interest in soft actuators with a large stroke, the so-called HASEL (hydraulically amplified self-healing electrostatic) actuators have become popular. It consists of a fluid-filled chamber between two compliant electrodes. When a voltage is applied, electrostatic attraction forces are generated due to charge separation, which cause the electrode area to zip. The hydrostatic pressure is guided to an area outside of the active electrodes and thus be used to apply forces and large displacement. According to the state of the art, manufacturing of HASEL actuators is frequently done manually or at least involves a significant amount of hands-on intervention. In addition, the handling of the fluid is accompanied by leakage problems. This article will present a process that enables additive manufacturing by using a 3D printing system. Therefore, the fluid must be frozen at around 5 degrees Celsius. A polymer layer is applied on top of the frozen fluid to seal it. The created HASEL actuators can be realized in different shapes and dimensions due to the easily adaptive 3D printing process. Subsequently, the achieved displacement is measured, characterized and evaluated.

Silicone-based dielectric elastomer actuators (DEAs) have been developed for various applications, including artificial muscles, loudspeakers, tunable lenses, and wearable haptic devices. Despite its popularity, PDMS suffers from low dielectric permittivity, limiting its potential for high-performance DEs. Efforts to enhance permittivity by incorporating high-k dielectric fillers like BaTiO₃ and TiO₂ have had limited success, as the increase in permittivity often leads to undesirable effects, such as higher elastic modulus and reduced dielectric breakdown strength. This study explores the use of dielectrophoretic (DEP) method to align dielectric particles in the thickness direction between the top and bottom electrodes in a DEs. By controlling the amplitude and frequency of the alternating voltage in DEP, the electrical properties of silicone composites can be tuned to suit for the application of dielectric electrical sensor and actuator.

The dielectric elastomer switch (DES) exhibits piezoresistivity through the periodic compression of a piezoresistive pattern by a dielectric elastomer actuator (DEA), both integrated on a shared substrate. DES is a versatile component in soft and stretchable electronics, with applications in inverters, oscillators, motors, logic gates, multiplexers, and soft robots. However, most previous studies have used VHB as the substrate, which has led to slower response times due to its high viscoelasticity. This work introduces silicone film as an alternative substrate to address the limitation. Carbon black (CB) ink is inkjet-printed onto the specially treated silicone film to form the piezoresistive pattern, which is then dried and pre-stretched to a specific ratio. Conductive silicone/CB compound electrodes are subsequently printed adjacent to the piezoresistive pattern via direct ink writing, completing the DES structure after curing. The ink properties, printing parameters, and the DES performance will be explored and discussed.

Poly(vinylidene fluoride) (PVDF) is an electroactive polymer with unique piezoelectric and triboeletric properties. Using Fused Filament Fabrication (FFF) to fabricate PVDF devices is still in its infancy, with only limited studies available in the literature. In this context, one challenge is obtaining a high electroactive β-phase content within the fabricated PVDF to maximize the material's electroactive properties. This work uses the FFF technique to fabricate PVDF smart materials to capture mechanical energy. Various printing parameters were studied to investigate their effect on the resultant structure in terms of electroactive β-phase formation. The varied printing parameters were nozzle diameter, printing speed, layer height, and temperature. The obtained structures were characterized using Fourier Transform Infrared (FTIR) technique and Differential Scanning Calorimetry (DSC) to quantify the β-phase content. Mechanical and electrical characterization was performed to evaluate the mechanical characteristics and output response of the manufactured structures.

Polyvinylidene fluoride (PVDF) and its copolymers are increasingly used in sensors, actuators, and energy harvesting due to their strong piezoelectric properties, flexibility, and optical transparency. The copolymer PVDF-TrFE, known for its enhanced piezoelectric performance and stability, is typically produced by solution casting, with annealing applied to improve properties. However, the impact of annealing and cooling rates on the piezoelectric, optical, and mechanical characteristics of PVDF-TrFE films remains unclear. This study explores the solution casting of PVDF-TrFE using a Dimethylformamide (DMF) and Acetone solution, followed by annealing near the melting temperature and cooling at different rates. Films cooled slowly (1-2°C/s) had higher β-phase content but reduced transparency, while those rapidly chilled in iced water showed lower β-phase content but better transparency. The correlation of surface properties with light scattering revealed surface roughness as the main factor influencing transparency. These insights can guide the development of surface treatments to optimize the optical as well as piezoelectric properties of PVDF-TrFE films.

Detection theory, developed during the era of radar imaging, is a method to discriminate among information-bearing patterns in data. It is fundamentally rooted in hypothesis testing. This presentation introduces the two general approaches to detection theory—Neyman-Pearson and Bayesian—and applies them to some applications in SHM/NDE. The generalization of Bayesian detection theory is then applied to optimal SHM/NDE system design.

In the late 1990’s, large, optical space structures were a hot topic. The astronomical community was planning the next big space telescopes after the success of the Hubble telescope, the Strategic Defense Initiative was exploring a Space-Based LASER for missile defense and other large, space telescopes were the subject of government and astronomical organizations. Common to all of these applications was the desire for a stiff telescope structure that had significant vibration damping. Since these two requirements are usually inversely related, the idea of incorporating smart structures using active damping and piezoceramic sensors and actuators became the subject of a large research effort at Air Force Research Lab—Advanced Composites with Embedded Sensors and Actuators.

Dielectric elastomer fiber actuators revolutionized artificial muscle development by utilizing DEA’s films efficiency, scalability and versatility in fiber geometry. Slicone-based fibers present high potential in reshaping actuation technology’s future due to unique softness and ease of production. We demonstrate polydimethylsiloxane fiber actuators produced using a photocurable reaction in a wet-spinning process. The hollow fiber’s size is controlled by varying flow rates, spinning head size and bath medium, enabling the fabrication of homogenous fibers with diameters of 300-2000 µm and wall thicknesses of 60–200 µm. The fiber’s robustness is assessed by correlating the curing conditions with rheological data, collected using the UV curing accessory. The fiber actuator is prepared by co-extruding or injecting the inner electrode and dip-coating the outer electrode. Various electrode materials, including conductive silicone composites, are investigated. The optimal fiber geometry is simulated, increasing the actuator’s reliability and allowing future incorporation into soft wearables.

We report a fabric actuator, designed for use in a soft exoskeleton, that can generate up to 40 N of force at 35% strain, and then lock in that displacement. Our actuator integrates Shape memory alloy (SMA) springs and electrostatic clutches (ESClutches), using the SMAs to generate large forces and the ESClutches to lock in the strain consuming only milliwatts of power. We can thus exploit the high force density of SMA while avoiding their high power consumption when holding a static position. Our thin fabric actuator weighs 55 grams and has a volume of 21 cm x 14 cm x 0.4 cm. We demonstrate two use cases, using it to lift a 2 kg weight and actively tightening an exoskeleton anchor around the waist. Our fabric actuator consumes 70% less energy than using SMAs alone.

The fabrication and testing of a stretchable transducer that can undergo high stretching without losing its electrical conductivity are presented. The functionalized textile thread is based on elastane and functionalized with poly(3,4-ethylenedioxythiophene). The thread exhibits high elasticity with a Young's modulus of 5.1 MPa. After quantified conditioning, the transducer achieves a gauge factor ranging from 0.4 to 15 when stretched between 5% and 100% strain. The absence of delamination of the conductive layer, even after 400% stretch, makes this transducer suitable for smart textiles and robotics applications. Moreover, the material's sensitivity at low strain and low forces makes it capable of differentiating airflows of interest. An application in airflow characterization at an industrial scale will be demonstrated.

DEAs are a key technology for developing artificial muscles, with strip actuators being particularly favored due to their low thickness, ease of fabrication, and adaptable dimensions. However, in long, slender designs, stretching can cause necking, affecting stress distribution and self-sensing accuracy. To address this, the study introduces a continuously reinforced actuator where stiff carbon fibers are integrated into a soft matrix, preventing necking and ensuring a uniform strain state. This approach provides a high degree of mechanical anisotropy without adding excessive stiffness and can serve as an electrode. Mechanical and electromechanical tests confirm improved performance, long-term stability, and suitability for practical soft robotics applications.

Dielectric Elastomer Actuators (DEAs) are a recent type of smart materials that show impressive performances as soft actuators and that have become new references when developing soft artificial muscles. Implementing dielectric elastomer actuators (DEAs) that mimic natural muscles has been proven difficult, as DEAs provide in-plane expansion when actuated, while natural muscles contract upon stimulation. Multiple solutions can be found in literature, namely stack DEAs and fiber reinforced DEAs. Currently, the fibers used for DEAs to achieve contractile motion rely on a fishnet design, where the angle between the fibers, the spacing, mechanical properties as well as the fiber dimensions can be set by establishing a fiber analytical model. In this work, contractile DEAs are investigated by embedding different fiber materials, both active and passive, and varying the mesh angle and applied loads.

Dielectric Elastomer Transducers (DETs) require ideal properties regarding e.g., a homogeneous dielectric thickness or electrode properties to achieve optimal performances. Inhomogeneities like manufacturing errors of the electrodes or varying dielectric thicknesses affect DET properties and thus their performance. To improve manufacturing processes and analyzing such imperfections, it is necessary to recognize and visualize those. Often, these inhomogeneities are not visible to the naked eye or with common visual characterization methods and can therefore not be characterized. To address this issue, in this paper a novel characterization approach using thermal imaging is presented. With this method, inhomogeneities and defects in both the electrodes and the dielectric can be made visible. The results show the feasibility of such measurements and the visualization of different imperfections.

Dielectric elastomer transducers (DE transducers) have been investigated for years and are constantly being developed. The advantages of DE-based sensor are the high achievable strains, the compatibility with the human movement and the potential simultaneous use as an additional actuator. A DE transducer has a comparatively small capacitance with a relevant internal series resistance due to the conductivity of the electrodes. The research challenge is to precisely determine this capacitance with a sufficient sampling rate in order to allow also sequential evolution of several sensors. Various techniques are used to evaluate a capacitance in general, such as the evaluation via the phase shift, the charging and discharging time, or more advanced the so-called capacitance-to-digital converters. The aim of this contribution is to examine these various techniques regarding their practical suitability for evaluating DE-based sensors. The methods will be implemented and validated using a microcontroller-based circuit board. Finally, a smart DE glove will be used to demonstrate the operation of the developed electronics using multiple sensors detecting the motion of a human hand.

Ionic polymer-metal composites (IPMCs) are flexible materials, but bending can cause cracks in their metal electrode layer, which reduces their performance. Scanning electrochemical microscopy (SECM) is used to visualize and assess the surface structure of IPMCs, including the integrity of the electrode layer and ion conduction efficiency. SECM also monitors moisture content and the effects of mechanical stress, identifying areas of deterioration, such as cracks or delamination. This technique enhances the understanding and development of more durable and efficient IPMC materials

The actuation performance of dielectric elastomers (DE) is determined by the electric field when voltage is applied. Due to local inhomogeneities and imperfections, the membrane may not reach the required electric field, reducing production yield. In previous work, a manual repair and patching process has been developed and presented. This process involves testing the DEs up to the required electric field and subsequent patching of early breakdown spots. This work presents the first Automated Dielectric Elastomer Actuator Performance-Tester ADEPT, which allows automatic breakdown tests and breakdown spot detection.

Silicone dielectric actuators have been demonstrated to be effective for a range of soft robotic applications. However, further material development is needed of the silicone dielectric layer itself to further progress the technology. The inherent low dielectric permittivity of silicone elastomers results in the requirement for high driving voltages. We demonstrate a novel approach to chemically bond ionic liquids to a silicone matrix, producing an elastomer suitable for low voltage actuation.

Ionic actuators commonly utilize water as a solvent to ensure ionic mobility. However, water can evaporate from the actuator when operated in air, severely deteriorating its performance. To address this problem, ionic liquids (ILs) have been proposed as an alternative solvent, guaranteeing stable operations over extended periods of time. Due to their complexity, models on IL-actuators are still untapped. Here, I propose a model to study actuation of ionic membranes with ionic liquids, considering the mobility of all ionic species in the membrane. Through systematic analyses, I highlight which material and ion parameters mostly affect the actuation performance, thus supporting the efforts of material scientists in material optimization.

Ionogels have attracted huge attention in the field of soft and stetchable smart materials... For such applications, ionogels are usually subjected to repeated deformation, making them susceptible to damage. Consequently, imparting these chemically crosslinked materials with healing ability is now required to repair and recycle wounded or broken materials and to improve their durability and sustainability. By introducing dynamic exchangeble bonds to these materials , namely dynamic β-hydroxyester functions, we have synthesized vitrimer ionogels that are soft, stretchable and conductive. Thanks to the presence of dynamic bonds, the ionogel shows full recovery of both tensile strength and conductivity properties after healing. While they can be directly used as high performance self-healable piezoresistive sensors, they can be also associated with a vitrimer elastomer based on the same chemistry, with enhanced adhesion allowing the fabrication of healable ionic cable to transmit music signal.

Ionic Polymer Metal Composites (IPMC) are a class of electroactive polymers that undergo actuation due to electrophoretic diffusion of counter-ions in a solvated cation-exchange membrane. For extended use, the actuator should retain its hydrated state and operate preferably under water. In this study we demonstrate an inexpensive and easy to fabricate encapsulation based on plasticized polyvinyl chloride that has been shown to extend the Ag-PFSA-Na+ IPMC actuator life. It has been experimentally verified that the coating being ultra-thin and flexible does not adversely impact the displacement. The surface resistivity measurements confirm that the effective resistivity of the electrode layer remains unaffected after coating. A comparative performance evaluation of the in-air actuation characteristics with and without coating have been carried out to establish the effectiveness of the encapsulation.

Developing soft actuators capable of multi-stimulus responses has become a key focus in advancing intelligent robotics and autonomous systems. This presentation explores integrating bio-inspired designs and innovative material systems, focusing on soft actuators that respond to various environmental stimuli such as light, heat, humidity, and electricity. Drawing from natural movements in plants and animals, we demonstrate how these systems can achieve versatile, life-like motions with minimal external control. Key innovations include ionomer-based actuators that enable complex autonomous behaviours like self-sustaining locomotion, phototropic responses, and adaptive changes to diverse environmental conditions. In particular, we highlight material-structural synergies, where high-performance polymers, such as Nafion combined with carbon nanotubes, facilitate dynamic responses through efficient energy conversion and structural feedback mechanisms. This multi-stimulus responsiveness allows for significant actuation diversity, including bending, coiling, and oscillatory movements, which are critical for applications in bio-hybrid soft robotics.