“Soft, stretchable, and unobtrusive”. These are some of the attributes frequently associated with capacitive dielectric elastomer (DE) sensors for body motion capture. While the sensors themselves are soft and elastic, they require rigid peripheral components for capacitance measurement. Each sensor is connected to a separate channel on the sensing circuitry through its own set of wires. In wearable applications with large numbers of sensors, this can lead to a considerable circuit board footprint, and cumbersome wiring. The additional equipment can obstruct movement and alter user behaviour. Previous work has demonstrated how a transmission line model can be applied to localise deformation on a single DE sensor. Building on this approach, we have developed a distributed sensing method by arranging capacitive DE sensors and external resistors to form a transmission line, which is connected to a single sensing channel with only one set of wires. The sensors are made from conductive fabric electrodes, and silicone dielectrics, and the external resistors are off-the-shelf metal film resistors. Excitation voltages with different frequencies are applied to the transmission line. The lumped transmission line capacitances at these frequencies are passed on to a mathematical model that calculates individual sensor capacitance changes. The prototype developed for this study is capable of obtaining separate readings for simultaneously stretched sensors.

Date Published: 17 April 2017
PDF: 10 pages
Proc. SPIE 10163, Electroactive Polymer Actuators and Devices (EAPAD) 2017, 1016306 (17 April 2017); doi: 10.1117/12.2260416

Published in SPIE Proceedings Vol. 10163:
Electroactive Polymer Actuators and Devices (EAPAD) 2017
Yoseph Bar-Cohen, Editor(s)