Measurement of PLGA-NP interaction with a single smooth muscle cell using optical tweezers
Author(s):
Ling Gu;
Argha Mondal;
Homa Homayoni;
Kytai Nguyen;
Samarendra Mohanty
Show Abstract
For intervention of cardiovascular diseases, biodegradable and biocompatible, poly(lactic-co-glycolic acid)
(PLGA) nanoparticles (NP) are emerging as agents of choice for controlled and targeted drug delivery. Therefore
development of PLGA-NP with optimal physico-chemical properties will allow efficient binding and thus delivery of
drug to targeted cells under various patho-physiological conditions. The force kinetics and its dependence on size of the
NPs will be crucial for designing the NPs. Since optical tweezers allow non-contact, highly sensitive force measurement
with high spatial and temporal resolution, we utilized it for studying interaction forces between magnetic
PLGA nanoparticles with smooth muscle cells (SMC). In order to investigate effect of size, interaction force for 200 to
1100nm PLGA NP was measured. For similar interaction duration, the force was found to be higher with increase in
size. The rupture force was found to depend on time of interaction of SMC with NPs.
Power optimization in wearable biomedical systems: a signal processing perspective
Author(s):
Hassan Ghasemzadeh
Show Abstract
Wearable monitoring systems have caught considerable attention recently due to their potential in many domains
including smart health and well-being. These new biomedical monitoring systems aim to provide continuous
patient monitoring and proactive care options. Realization of this vision requires research that addresses a
number of challenges, in particular, regarding limited resources that the wearable sensor networks offer. This
paper presents an overview of different strategies for prolonging system lifetimes through power optimization
in such systems. Particular emphasis is given to enhancing processing and communication architectures with
respect to the signal processing requirements of the system.
Portable guided-mode resonance biosensor platform for point-of-care testing
Author(s):
Gun Yong Sung;
Wan-Joong Kim;
Hyunsung Ko;
Bong Kyu Kim;
Kyung-Hyun Kim;
Chul Huh;
Jongcheol Hong
Show Abstract
It represents a viable solution for the realization of a portable biosensor platform that could screen/diagnose acute
myocardial infarction by measuring cardiac marker concentrations such as cardiac troponin I (cTnI), creatine kinase MB
(CK-MB), and myoglobin (MYO) for application to u-health monitoring system. The portable biosensor platform
introduced in this presentation has a more compact structure and a much higher measuring resolution than a conventional
spectrometer system. Portable guided-mode resonance (GMR) biosensor platform was composed of a biosensor chip
stage, an optical pick-up module, and a data display panel. Disposable plastic GMR biosensor chips with nano-grating
patterns were fabricated by injection–molding. Whole blood filtration and label-free immunoassay were performed on
these single chips, automatically. Optical pick-up module was fabricated by using the miniaturized bulk optics and the
interconnecting optical fibers and a tunable VCSEL (vertical cavity surface emitting laser). The reflectance spectrum
from the GMR biosensor was measured by the optical pick-up module. Cardiac markers in human serum with
concentrations less than 0.1ng/mL were analyzed using a GMR biosensor. Analysis time was 30min, which is short
enough to meet clinical requirements. Our results show that the GMR biosensor will be very useful in developing lowcost
portable biosensors that can screen for cardiac diseases.
Army relevant Biological Hazards Detection with Commercial SERS substrates
Author(s):
Mikella E. Farrell;
Paul M. Pellegrino
Show Abstract
There is an increasing need and challenge for early rapid and accurate detection, identification, and quantification of
chemical, biological, and energetic hazards in many fields of interest (e.g., medical, environmental, industrial, and
defense applications). Increasingly to meet these challenges, researchers are turning to interdisciplinary approaches
combining spectroscopy with nanoscale platforms to create technologies that offer viable and novel solutions for today’s
sensing needs. One technology that has gained increasing popularity to meet these needs is surface enhanced Raman
scattering (SERS). SERS is particularly advantageous as it does not suffer from interferences from water, requires little
to no sample preparation, is robust and can be used in numerous environments, is relatively insensitive to the wavelength
of excitation employed and produces a narrow-band spectral signature unique to the molecular vibrations of the analyte.
SERS enhancements (chemical and electromagnetic) are typically observed on metalized nanoscale roughened surfaces.
For ideal SERS sensing, a commercially available uniform and reproducible nanoscale surface demonstrating high
sensitivity are desirable. Additionally, if these surfaces can be modified for the selective sensing of hazard materials, an
ideal sensor platform for dynamic in field measurements can be imagined. In this proceedings paper, preliminary efforts
towards the characterization and application of commercially available next generation Klarite substrates will be
demonstrated. Additionally, efforts toward chemical modification of these substrates, through peptide recognition
elements, can be used for the targeted sensing of hazardous materials.
A viral peptide for intracellular delivery
Author(s):
Annarita Falanga;
Rossella Tarallo;
Marco Cantisani;
Maria Elena Della Pepa;
Massimiliano Galdiero;
Stefania Galdiero
Show Abstract
Biological membranes represent a critical hindrance for administering active molecules which are often unable to reach their designated intracellular target sites. In order to overcome this barrier-like behavior not easily circumvented by many pharmacologically-active molecules, synthetic transporters have been exploited to promote cellular uptake. Linking or complexing therapeutic molecules to peptides that can translocate through the cellular membranes could enhance their internal delivery, and consequently, a higher amount of active compound would reach the site of action. Use of cell penetrating peptides (CPPs) is one of the most promising strategy to efficiently translocate macromolecules through the plasma membrane, and have attracted a lot of attention. New translocating peptides are continuously described and in the present review, we will focus on viral derived peptides, and in particular a peptide (gH625) derived from the herpes simplex virus type 1 (HSV-1) glycoprotein H (gH) that has proved to be a useful delivery vehicle due to its intrinsic properties of inducing membrane perturbation.
Electrochemical enzymatic biosensors using carbon nanofiber nanoelectrode arrays
Author(s):
Jun Li;
Yi-fen Li;
Luxi Z. Swisher;
Lateef U. Syed;
Allan M. Prior;
Thu Annelise Nguyen;
Duy H. Hua
Show Abstract
The reduction of electrode size down to nanometers could dramatically enhance detection sensitivity and
temporal resolution. Nanoelectrode arrays (NEAs) are of particular interest for ultrasensitive biosensors. Here
we report the study of two types of biosensors for measuring enzyme activities using NEAs fabricated with
vertically aligned carbon nanofibers (VACNFs). VACNFs of ~100 nm in average diameter and 3-5 μm in
length were grown on conductive substrates as uniform vertical arrays which were then encapsulated in SiO2
matrix leaving only the tips exposed. We demonstrate that such VACNF NEAs can be used in profiling
enzyme activities through monitoring the change in electrochemical signals induced by enzymatic reactions to
the peptides attached to the VACNF tip. The cleavage of the tetrapeptide with a ferrocene tag by a cancerrelated
protease (legumain) was monitored with AC voltammetry. Real-time electrochemical impedance
spectroscopy (REIS) was used for fast label-free detection of two reversible processes, i.e. phosphorylation by
c-Src tyrosine kinase and dephosphorylation by protein tyrosine phosphatase 1B (PTP1B). The REIS data of
phosphorylation were slow and unreliable, but those of dephosphorylation showed large and fast exponential
decay due to much higher activity of phosphatase PTP1B. The kinetic data were analyzed with a
heterogeneous Michaelis-Menten model to derive the “specificity constant” kcat/Km, which is 8.2x103 M-1s-1
for legumain and (2.1 ± 0.1) x 107 M-1s-1 for phosphatase (PTP1B), well consistent with literature. It is
promising to develop VACNF NEA based electrochemical enzymatic biosensors as portable multiplex
electronic techniques for rapid cancer diagnosis and treatment monitoring.
Light trapping and enhancing gold nanoparticle array substrates made by thermal dewetting technique
Author(s):
T. W. Chang;
H. Jin;
G. L. Liu
Show Abstract
In this paper, we fabricated gold particle array substrate by thermal dewetting technique. The fabrication process is
simple, reliable, cost efficient with comparing to other techniques. From optical characteristic it shows light trapping
ability to reduce reflectance around 75%. Combining light trapping and its localized plasmonic properties, this substrate
has significant advantages on plasmonic based sensing methods such as surface enhanced Raman scattering (SERS).
SERS measurement has been performed and the enhancement factor is 2.58×105. Further more, after silver thin film
deposition the enhancement can be increased up to 2 orders and the enhancement factor is 3.66×107.
Photothermal nanoblade for single cell surgery and cargo delivery
Author(s):
Pei-Yu Chiou;
Ting-Hsiang Wu;
Michael A Teitell M.D.
Show Abstract
This work presents a novel photothermal nanoblade that utilizes metallic nanostructures to light energy from
short laser pulses to generate highly localized and shaped explosive cavitation bubbles which enables rapid cut of a
lightly contacting cell membrane of a mammalian cell. Photothermal nanoblade can generate micrometer-sized
membrane access ports for delivering large size cargo with high efficiency and high cell viability. Biologic and
inanimate cargo over 3-orders of magnitude in size including DNA, RNA, 200 nm polystyrene beads, to 2 μm bacteria
have also been successfully delivered into multiple mammalian cell types.
Electrical detection of specific versus non-specific binding events in breast cancer cells
Author(s):
Benjamin C. King;
Michael Clark;
Thomas Burkhead;
Palaniappan Sethu;
Shesh Rai;
Goetz Kloecker;
Balaji Panchapakesan
Show Abstract
Detection of circulating tumor cells (CTCs) from patient blood samples offers a desirable alternative to invasive tissue biopsies for screening of malignant carcinomas. A rigorous CTC detection method must identify CTCs from millions of other formed elements in blood and distinguish them from healthy tissue cells also present in the blood. CTCs are known to overexpress surface receptors, many of which aid them in invading other tissue, and these provide an avenue for their detection. We have developed carbon nanotube (CNT) thin film devices to specifically detect these receptors in intact cells. The CNT sidewalls are functionalized with antibodies specific to Epithelial Cell Adhesion Molecule (EpCAM), a marker overexpressed by breast and other carcinomas. Specific binding of EpCAM to anti-EpCAM antibodies causes a change in the local charge environment of the CNT surface which produces a characteristic electrical signal. Two cell lines were tested in the device: MCF7, a mammary adenocarcinoma line which overexpresses EpCAM, and MCF10A, a non-tumorigenic mammary epithelial line which does not. Introduction of MCF7s caused significant changes in the electrical conductance of the devices due to specific binding and associated charge environment change near the CNT sidewalls. Introduction of MCF10A displays a different profile due to purely nonspecific interactions. The profile of specific vs. nonspecific interaction signatures using carbon based devices will guide development of this diagnostic tool towards clinical sample volumes with wide variety of markers.
Combined SERS biotags (SBTs) and microfluidic platform for the quantitative ratiometric discrimination between noncancerous and cancerous cells in flow
Author(s):
Alessia Pallaoro;
Mehran R. Hoonejani;
Gary B Braun;
Carl Meinhart;
Martin Moskovits
Show Abstract
SERS biotags are made from polymer-encapsulated silver nanoparticle dimers infused with unique Raman reporter molecules, and carry peptides as cell recognition moieties. We demonstrate their potential use for early and rapid identification of malignant cells, a central goal in cancer research. SERS biotags (SBTs) can be routinely synthesized and simultaneously excited with a single, low intensity laser source, making the determination of the relative contribution of the individual SBTs to the overall spectrum tractable. Importantly for biomedical applications, SERS employs tissuepenetrating lasers in the red to near-infrared range resulting in low autofluorescence. We have previously described a multiplexed, ratiometric method that can confidently distinguish between cancerous and noncancerous epithelial prostate cells in vitro based on receptor overexpression. Here we present the progress towards the application of this quantitative methodology for the identification of cancer cells in a microfluidic flow-focusing device. Beads are used as cell mimics to characterize the devices. Cells (and beads) are simultaneously incubated with two sets of SBTs while in suspension (simulating cells’ capture from blood), then injected into the device for laser interrogation under flow. Each cell event is characterized by a composite Raman spectrum, deconvoluted into its single components to ultimately determine their relative contribution. We show that using SBTs ratiometrically can provide cell identification insensitive to normal causes of uncertainty in optical measurements such as variations in focal plane, cell concentration, autofluorescence, and turbidity.
Towards increased selectivity of drug delivery to cancer cells: development of a LDL-based nanodelivery system for hydrophobic photosensitizers
Author(s):
Diana Buzova;
Veronika Huntosova;
Peter Kasak;
Dana Petrovajova;
Jaroslava Joniova;
Lenka Dzurova;
Zuzana Nadova;
Franck Sureau;
Pavol Miskovsky;
Daniel Jancura
Show Abstract
Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the
delivery of hydrophobic photosensitizers (pts) to tumor cells in photodynamic therapy (PDT) of cancer. To make this
delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by
polyethylene glycol (PEG) and dextran. Fluorescence spectroscopy and confocal fluorescence imaging were used to
characterize redistribution of hypericin (Hyp), a natural potent pts, loaded in LDL/PEG and LDL/dextran complexes to
free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It was shown than the redistribution
process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. On the other
hand, PEG does not significantly influence this process. The modification of LDL molecules by the polymers does not
inhibit their recognition by cellular LDL receptors. U-87 MG cellular uptake of Hyp loaded in LDL/PEG and
LDL/dextran complexes appears to be similar to that one observed for Hyp transported by unmodified LDL particles. It
is proposed that by polymers modified LDL molecules could be used as a basis for construction of a drug transport
system for targeted delivery of hydrophobic drugs to cancer cells expressing high level of LDL receptors.
Characterization of oil nano-structures with monochromatic x-ray micro-tomography
Author(s):
Victor E. Asadchikov;
Alexey V. Buzmakov;
Anna S. Osadchaya;
Denis A. Zolotov;
Michael K. Rafailov
Show Abstract
Here we report work done toward detection and characterization of micro-and nano-structures in bitumen, including
mineral particles-clay and sand as well as metal-organic micro-and nano-structures containing porphyrines. X-ray
micro-tomograph with monochromatic radiation has been used for detection of the structures. In order to detect and
characterize nano-and micro-structures tomograph’s operational wavelength has been tuned to absorption wavelength of “chemical element of interest” X-ray spectrum: whatever it is Si or porphyrine-forming metals like V, Ni, Co. Contrast between X-ray absorption of micro-structures containing specific element and average bitumen’s environment absorption provides a tool for measurement of element mass concentration as well as size and mass density distributions of micro-and nano structures not only on surface but in bitumen volume. Specifically the most interest is in measurement of vanadyl porphyrines and other metal containing chemicals in asphaltene micro-structures changing per asphalten concentration due to bitumen processing.
Controlled FRET efficiency in nano-bio hybrid materials made from semiconductor quantum dots and bacteriorhodopsin
Author(s):
Nicolas Bouchonville;
Anthony Le Cigne;
Alyona Sukhanova;
Marie-belle Saab;
Michel Troyon;
Michael Molinari;
Igor Nabiev
Show Abstract
Förster resonance energy transfer (FRET) between CdSe/ZnS core/shell quantum dots (QDs) and the photochromic
protein bacteriorhodopsin (bR) in its natural purple membrane (PM) has been modulated by independent tuning of the Förster radius, overlap integral of the donor emission spectrum and acceptor absorption spectrum, and the distance between the donor (QD) and acceptor (bR retinal). The results have shown that the observed energy transfer from QDs to bR corresponds to that predicted by a multiple-acceptors geometric model describing the FRET phenomenon for QDs quasi-epitaxied on a crystalline lattice of bR trimers. Linking of QDs and bR via streptavidin–biotin linkers of different lengths caused FRET with an efficiency reaching 82%, strongly exceeding the values predicted by the classical FRET theory. The data not only demonstrate the possibility of nano-bioengineering of efficient hybrid materials with controlled energy-transfer properties, but also emphasize the necessity to develop an advanced theory of nano–bio energy transfer that would explain experimental effects contradicting the existing theoretical models.
Biosensing with thermosensitive fluorescent quantum dot-containing polymer particles
Author(s):
Alla N. Generalova;
Vladimir A Oleinikov;
Alyona Sukhanova;
Mikhail V. Artemyev;
Vitaly P. Zubov;
Igor Nabiev
Show Abstract
In the past decades, increasing attention has been paid to the preparation of “smart” functionalized polymer particles
reversibly responding to slight environmental changes, such as variations in temperature, pH, and ionic strength. The
composite polymer particles consisting of a solid poly(acrolein-co-styrene) core and a poly(N-vinylcaprolactam) (PVCL)
polymer shell doped with CdSe/ZnS semiconductor quantum dots (QDs) were prepared. The thermosensitive response of
the composite particles was observed as a decrease in their hydrodynamic diameter upon heating above the lower critical
solution temperature of the thermosensitive PVCL polymer used as a shell. Embedding QDs in the PVCL shell makes it
possible to obtain particles whose fluorescence is sensitive to temperature changes. The temperature-dependent
fluorescence of particles was determined by reversible variation of the distances between QDs in the PVCL shell as a
result of temperature-driven conformational changes in this polymer. In addition, these particles can be used as carriers
of biomolecule (e.g., bovine serum albumin, BSA) characterized by reversibly temperature-dependent fluorescence,
which can serve as the basis for optical detection methods in bioassays, such as the measurement of local temperature in
nanovolumes, biosensing, etc.
Porous silicon photonic crystals for detection of infections
Author(s):
B. Gupta;
B. Guan;
P. J. Reece;
J. J. Gooding
Show Abstract
In this paper we demonstrate the possibility of modifying porous silicon (PSi) particles with surface chemistry and
immobilizing a biopolymer, gelatin for the detection of protease enzymes in solution. A rugate filter, a one-dimensional
photonic crystal, is fabricated that exhibits a high-reflectivity optical resonance that is sensitive to small changes in the
refractive index. To immobilize gelatin in the pores of the particles, the hydrogen-terminated silicon surface was first
modified with an alkyne, 1,8-nonadiyne via hydrosilylation to protect the silicon surfaces from oxidation. This
modification allows for further functionality to be added such as the coupling of gelatin. Exposure of the gelatin
modified particles to the protease subtilisin in solution causes a change in the refractive index, resulting in a shift of the
resonance to shorter wavelengths, indicating cleavage of organic material within the pores. The ability to monitor the
spectroscopic properties of microparticles, and shifts in the optical signature due to changes in the refractive index of the
material within the pore space, is demonstrated.
Biosensing with integrated CMOS nanopores
Author(s):
Ashfaque Uddin;
Sukru Yemenicioglu;
Chin-Hsuan Chen;
Ellie Corgliano;
Kaveh Milaninia;
Fan Xia;
Kevin Plaxco;
Luke Theogarajan
Show Abstract
This paper outlines our recent efforts in using solid-state nanopores as a biosensing platform. Traditionally biosensors concentrate mainly on the detection platform and not on signal processing. This decoupling can lead to inferior sensors and is exacerbated in nanoscale devices, where device noise is large and large dynamic range is required. This paper outlines a novel platform that integrates the nano, micro and macroscales in a closely coupled manner that mitigates many of these problems. We discuss our initial results of DNA translocation through the nanopore. We also briefly discuss the use of molecular recognition properties of aptamers with the versatility of the nanopore detector to design a new class of biosensors in a CMOS compatible platform.
Laser lift-off of GaN thin film and its application to the flexible light emitting diodes
Author(s):
Seung Hyun Lee;
So Young Park;
Keon Jae Lee
Show Abstract
The high performance GaN light emitting diode (LED) from sapphire wafer has been transferred on a plastic substrate
with 308nm XeCl laser lift-off (LLO) for next generation flexible lighting applications. SU-8 passivation with
thermal release tape (TRT) adhesive enables structure coverage and adhesion so that it can be an excellent candidate for
a carrier substrate for non-wetting transfer process using laser liftoff technology. The dimensions of the laser beam are
also investigated in two types (3μm x 5cm and 1.2mm x 1.2mm) to reduce stress when decomposition of GaN occurs.
With careful optimization of carrier substrate and laser beam conditions, we can fabricate flexible GaN LED on
polyimide substrates which shows similar electrical properties to the GaN LED on bulk sapphire substrate.
Single-photon sensitive Geiger-mode ladar cameras
Author(s):
Ping Yuan;
Rengarajan Sudharsanan;
Xiaogang Bai;
Paul McDonald;
Eduardo Labios;
Bryan Morris;
John P. Nicholson;
Gary M. Stuart;
Harrison Danny
Show Abstract
Three-dimensional (3D) imaging with Short wavelength infrared (SWIR) Laser Detection and Range (LADAR) systems have been successfully demonstrated on various platforms. It has been quickly adopted in many military and civilian applications. In order to minimize the LADAR system size, weight, and power (SWAP), it is highly desirable to maximize the camera sensitivity. Recently Spectrolab has demonstrated a compact 32x32 LADAR camera with single photo-level sensitivity at 1064. This camera has many special features such as non-uniform bias correction, variable range gate width from 2 microseconds to 6 microseconds, windowing for smaller arrays, and short pixel protection. Boeing
integrated this camera with a 1.06 μm pulse laser on various platforms and demonstrated 3D imaging. The
features and recent test results of the 32x128 camera under development will be introduced.
A photon-counting camera system developed from a crossed-strip detector
Author(s):
Jonathan M. Cook;
Joseph M. Palmer;
Ellen C. S. Rabin;
Laura C. Stonehill;
David C. Thompson;
Stephen R. Whittemore;
Michael D. Ulibarri
Show Abstract
A crossed-strip detector initially developed at UC Berkeley’s Space Sciences Laboratory has been demonstrated
as a laboratory benchtop instrument and is now in the process of being integrated by Los Alamos National
Laboratory into a portable, real-time, single-photon-counting camera system. The crossed-strip detector consists
of 32 anode strips along each of two axes sealed inside a vacuum tube behind a photocathode and a microchannelplate
stack. A photon incident on the photocathode produces a cloud of charge from the microchannel plates
that falls onto a portion of the 64 anode strips, producing a signal on a subset of channels along each axis and
requiring that all anode channels continually be analyzed simultaneously. To maximize the photon flux that
can be accepted by the sensor with minimal deadtime, the crossed-strip sensor has been combined with shortershaping-
time amplifiers and higher-rate digitizers than previously used. With the ultimate goal of reaching 100
million events per second, FPGA-implementable algorithms have been developed for the identification of pulses
on each anode channel and the determination of the pulses’ time and amplitude. From the pulse times and
amplitudes, a charge cloud can be reconstructed and the centroid determined to produce the time and position
of each incident photon. The data-analysis procedure will be discussed, measurements detailing the performance
of the camera system as it exists at this point will be presented, and the planned layout of the embedded camera
system hardware will be detailed.
Temperature dependence of the dark current and activation energy at avalanche onset of a GaN avalanche photodiodes
Author(s):
M. P. Ulmer;
E. Cicek;
R. McClintock;
Z. Vashaei;
M. Razeghi
Show Abstract
We report a study of the performance of an avalanche photodiode (APD) as a function of temperature from
564 K to 74 K. The dark current at avalanche onset decreases from 564 K to 74 K by approximately a factor of
125 and from 300 K to 74K the dark current at avalanche offset is reduced by a factor of about 10. The drop
would have been considerably larger if the activation energy at avalanche onset (Ea) did not also decrease with
decreasing temperature. These data give us insights into how to improve the single-photon counting performance
of a GaN based ADP.
Balanced InGaAs/InP avalanche photodiodes for single photon detection
Author(s):
Zhiwen Lu;
Wenlu Sun;
Xiaoguang Zheng;
Joe Campbell;
Xudong Jiang;
Mark A. Itzler
Show Abstract
Abstract—We demonstrate a sinusoidally-gated InGaAs/InP photodiode pair operated at wavelength of 1310 nm with high photon detection efficiency (PDE) and low dark count rate (DCR). The photodiode pair is biased in a balanced scenario so that the common component of the output signal is cancelled. The concept of balanced photodiodes helps improve detection efficiency while canceling the common mode signal, which, in this case, is the capacitive response of the photodiodes. In conventional sinusoidal gating, an extra component, – an RF filter (or several) at the gating frequency, is utilized to filter out the gating signal and leave the avalanche signal for detection. For this configuration, sinusoidally-gated counting systems are restricted to a single frequency. With the balanced single photon diodes (SPAD), sinusoidal gating within a continuous frequency range is feasible. A printed circuit with symmetric layout of two bias tees was fabricated on a duroid board to enable the application of AC and DC signals for the dual SPADs. At a laser repletion rate of 1 MHz and temperature of 240 K the DCR and PDE were 58 kHz and 43%, respectively. Afterpulsing probability was lower compared with a sinusoidually-gated single SPAD. Jitter of 240 ps was achieved with 1 photon per pulse for an excess bias of 1.6%.
Depth imaging at kilometer range using time-correlated single-photon counting at wavelengths of 850 nm and 1560 nm
Author(s):
Gerald S. Buller;
Aongus McCarthy;
Ximing Ren;
Nathan R. Gemmell;
Robert J. Collins;
Nils J. Krichel;
Michael G. Tanner;
Andrew M. Wallace;
Sandor Dorenbos;
Val Zwiller;
Robert H. Hadfield
Show Abstract
Active depth imaging approaches are being used in a number of emerging applications, for example in
environmental sensing, manufacturing and defense. The high sensitivity and picosecond timing resolution of the
time-correlated single-photon counting technique can provide distinct advantages in the trade-offs between
required illumination power, range, depth resolution and data acquisition durations. These considerations must
also address requirements for eye-safety, especially in applications requiring outdoor, kilometer range sensing.
We present a scanning time-of-flight imager based on MHz repetition-rate pulsed illumination operating with
sub-milliwatt average power. The use of a scanning mechanism permits operation with an individual, high-performance
single-photon detector. The system has been used with a number of non-cooperative targets, in
different weather conditions and various ambient light conditions. We consider a number of system issues,
including the range ambiguity issue and scattering from multiple surfaces. The initial work was performed at
wavelengths around 850 nm for convenient use with Si-based single photon avalanche diode detectors, however
we will also discuss the performance at a wavelength of 1560 nm, made using superconducting nanowire single
photon detectors. The use of the latter wavelength band allows access to a low-loss atmospheric window, as well
as greatly reduced solar background contribution and less stringent eye safety considerations. We consider a
range of optical design configurations and discuss the performance trade-offs and future directions in more
detail.
3D near-infrared imaging based on a single-photon avalanche diode array sensor
Author(s):
Juan Mata Pavia;
Martin Wolf;
Edoardo Charbon
Show Abstract
Near-infrared light can be used to determine the optical properties (absorption and scattering) of human tissue. Optical tomography uses this principle to image the internal structure of parts of the body by measuring the light that is scattered in the tissue. An imager for optical tomography was designed based on a detector with 128x128 single photon pixels that included a bank of 32 time-to-digital converters. Due to the high spatial resolution and the possibility of performing time resolved measurements, a new contactless setup has been conceived. The setup has a resolution of 97ps and operates with a laser source with an average power of 3mW. This new setup generated an high amount of data that could not be processed by established methods, therefore new concepts and algorithms were developed to take advantage of it. Simulations show that the potential resolution of the new setup would be much higher than previous designs. Measurements have been performed showing its potential. Images derived from the measurements showed that it is possible to reach a resolution of at least 5mm.
Aspects of chip and cell size of silicon photomultipliers
Author(s):
P. Iskra;
Christoph Dietzinger;
T. Eggert;
M. Fraczek;
T. Ganka;
L. Höllt;
J. Knobloch;
N. Miyakawa;
A. Pahlke;
F. Wiest;
R. Fojt
Show Abstract
Requirements like device miniaturization, insensitivity to magnetic field and cost aspects in the field of low level light detection will lead to a replacement of the conventional photomultiplier tube by Silicon Photomultiplier (SiPM) for several applications in case the photon detection efficiency will be comparably higher at the same price level. This novel solid-state sensor consists of an array of parallel connected avalanche photodiodes
operated in limited Geiger-mode. The triggered cells are recovered by an upstream connected quenching resistor.
The main characteristics are gain, noise, photon detection efficiency (PDE), dynamic range and time resolution.
To meet the requirements of various potential applications, SiPMs need to be available with several micro pixel
sizes and total active areas. For this reason KETEK produces devices with microcell pitches from 15μm up to
100μm and total active sensor areas from 1.0 x 1.0 mm2 up to 6.0 mm x 6.0 mm2. The effects of this scaling on the SiPM device parameters are discussed.
Reduction of optical crosstalk in silicon photomultipliers
Author(s):
Ch. Dietzinger;
P. Iskra;
Thomas Ganka;
T. Eggert;
Lothar Höllt;
A. Pahlke;
N. Miyakawa;
M. Fraczek;
J. Knobloch;
F. Wiest;
W. Hansch;
R. Fojt
Show Abstract
The Silicon Photomultiplier (SiPM) is a novel device for low level light detection in various applications, for example scintillator- and fiber readout.1;2 The SiPM is insensitive to magnetic fields and has a high photon detection effciency. Current devices have a high optical crosstalk probability, which causes a significant increase of the excess noise factor.3 It may replace traditional Photo Multiplier Tubes (PMT) when the optical crosstalk is reduced to a lower level of below 10%. Depending on the quantity of hot electrons in the Geiger discharge approximately three to fifty secondary photons (in average three photons per 105 avalanche electrons4) with a wavelength range from 450nm to 1600nm are emitted from the excited cell in all directions.5 Some of those secondary photons cause the discharge of the neighboring cell.6;7 The different mechanism of optical crosstalk are categorized as direct and indirect crosstalk. To reduce direct crosstalk an optical barrier has to be implemented between the single micro cells.8 Thus, we have investigated different technological concepts with regard to the trench shape, the trench etching process as well as the trench fill material.
FAMOUS: a prototype silicon-photomultiplier telescope for the fluorescence detection of ultra-high-energy cosmic rays
Author(s):
Markus Lauscher;
Pedro Assis;
Pedro Brogueira;
Miguel Ferreira;
Thomas Hebbeker;
Luís Mendes;
Christine Meurer;
Lukas Middendorf;
Tim Niggemann;
Mário Pimenta;
Johannes Schumacher;
Maurice Stephan
Show Abstract
A sophisticated technique to study ultra-high-energy cosmic rays is to measure the extensive air showers they
cause in the atmosphere. Upon impact on the atmosphere, the cosmic rays generate a cascade of secondary particles,
forming the air shower. The shower particles excite the atmospheric nitrogen molecules, which emit fluorescence
light in the near ultraviolet regime when de-exciting. Observation of the fluorescence light with suitable
optical telescopes allows a reconstruction of the energy and arrival direction of the initial particle. Due to their
high photon detection efficiency, silicon photomultipliers (SiPMs) promise to improve current photomultipliertube-
based fluorescence telescopes. We present the design and a full detector simulation of an SiPM-based
fluorescence telescope prototype, together with the expected telescope performance, and our first construction
steps. The simulation includes the air showers, the propagation of the fluorescence light through the atmosphere
and its detection by our refracting telescope. We have also developed a phenomenological SiPM model based on
measurements in our laboratories, simulating the electrical response. This model contains the photon detection
efficiency, its dependence on the incidence angle of light and the effects of thermal and correlated noise. We have
made a full performance analysis for the detection of air showers including the environmental background light.
Moreover, we will present the RandD in compact modular electronics using photon counting techniques for the
telescope readout.