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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Patrick C. Mathias Nikhil Ganesh Brian T. Cunningham Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign USA Department of Material Science and Engineering University of Illinois Urbana-Champaign USA Department of Bioengineering University of Illinois Urbana-Champaign USA

Photonic crystal surfaces are demonstrated as a means for enhancing the detection sensitivity and resolution for assays that use a fluorescent tag to quantify the concentration of an analyte protein molecule in a liquid test sample. computer modeling of the spatial distribution of resonantly coupled electromagnetic fields on the photonic crystal surface are used to estimate the magnitude of enhancement factor compared to performing the same fluorescent assay on a plain glass surface, and the photonic crystal structure is fabricated and tested to experimentally verify the performance using a sandwich immunoassay for the protein Tumor Necrosis Factor-alpha (TNF-alpha). The demonstrated photonic crystal fabrication method utilizes a nanoreplica molding technique that allows for large-area inexpensive fabrication of the structure in a format that is compatible with confocal microarray laser scanners. The signal-to-noise ratio for fluorescent spots on the photonic crystal is increased by at least five-fold relative to the glass slide, allowing a TNF-alpha concentration of 1.6 pg/ml to be distinguished from noise on a photonic crystal surface. In addition, the minimum quantitative limit of detection on the photonic crystal surface is one-third the limit on the glass slide - a decrease from 18 pg/ml to 6 pg/ml. The increased performance of the immunoassay allows for more accurate quantitation of physiologically relevant concentrations of TNF-alpha in a protein microarray format that can be expanded to multiple cytokines.

关键词： Photonic crystals Immunity testing Fluorescence Proteins Glass Optical device fabrication Signal to noise ratio Spatial resolution Distributed computing Optical computing

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Reconstructing FT-IR spectroscopic imaging data with a sparse prior

Reconstructing FT-IR spectroscopic imaging data with a spars...

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IEEE International Conference on Image Processing

作者： Spencer P. Brady Minh N. Do Rohit Bhargava Department of Electrical and Computer Engineering and Coordinated Science Laboratory University of Illinois Urbana-Champaign USA Department of Bioengineering and Beckman Institute of Advanced Science and Technology University of Illinois Urbana-Champaign USA

Fourier Transform Infrared (FT-IR) spectroscopic imaging is a potentially valuable tool for diagnosing breast and prostate cancer, but its clinical deployment is limited due to long data acquisition times and vast storage requirements. To counter this limitation, we develop a sparse representation for FT-IR absorbance spectra using a learned dictionary. This sparse representation is used as prior knowledge in regularizing the compressed sensing inverse problem. The data size and acquisition time are directly proportional to the length of the measured signal, namely the interferogram. Hence, we model our measurement process as interferogram truncation, which we implement by low pass filtering and downsampling in the spectral domain. With a downsample factor of four, our reconstruction is adequate for tissue classification and provides a Peak Signal-to-noise Ratio (PSNR) of 41.92 dB, while standard interpolation of the same low resolution measurements can only provide a PSNR of 36.93 dB.

关键词： Image reconstruction Spectroscopy PSNR Optical imaging Infrared spectra Image storage Fourier transforms Infrared imaging Breast Prostate cancer

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Patterning of SU-8 resist with Digital Micromirror Device (DMD) maskless lithography

Patterning of SU-8 resist with Digital Micromirror Device (D...

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Optical Microlithography XXII

作者： Wang, Tao Quaglio, Marzia Pirri, Fabrizio Cheng, Yang-Chun Busacker, David Cerrina, Franco Center for Nanotechnology University of Wisconsin-Madison Madison WI 53706 United States Materials Science Program University of Wisconsin-Madison Madison WI 53706 United States Polytechnic of Torino Physics Department Materials and Microsystems Laboratory C. so Duca degli Abruzzi 24 I-10129 Torino Italy Department of Electrical and Computer Engineering University of Wisconsin-Madison Madison WI 53706 United States Department of Electrical and Computer Engineering Boston University Boston MA 02215 United States

ISBN: (纸本)9780819475275

Digital micromirror device (DMD) based maskless lithography has a number of advantages including process flexibility, no physical photomask requirement, fast turnaround time, cost effectiveness. It can be particularly useful in the development stage of microfluidic and bioMEMS applications. In this report, we describe the initial results of thick resist SU-8 patterning, soft lithography with polydimethylsiloxane (PDMS) and lift-off of Cr features using a modified DMD maskless system. Exposures of various patterns and microfluidic channels reveal that the system is well capable of printing 60 μm thick resist at a resolution as small as a single pixel (less than 13 μm) with an aspect ratio about 5:1. Both negatively and positively tapered sidewalls are achieved by projecting the UV light from front side of the SU-8 coated Si wafer and from the back side of the coated glass, respectively. The positive sidewall has an angle 88 which is ideal to serve as a mold for subsequent PDMS soft lithography. Both SU-8 and PDMS microfluidic devices for biomolecular synthesis were fabricated with this maskless system. In addition, a lift-off process was also developed with the intention to create built-in metal features such as electrodes and heaters. © 2009 SPIE.

关键词： Microfluidics

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A neuromorphic head direction cell system

A neuromorphic head direction cell system

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Tarek M. Massoud Timothy K. Horiuchi Electrical and Computer Engineering Department Institute of Systems Research Neuroscience and Cognitive Science Program University of Maryland College Park MD USA

ISBN: (纸本)9781424438273

The head direction (HD) cell system in the brain of mammals is thought to be part of the neural circuitry supporting their spatial navigation capabilities. In this paper we present a neuromorphic VLSI system that mimics the operation of the HD system. Relying on spiking neurons and attractor dynamics, this system can be used to represent and retain the current estimate of head orientation in the environment and integrate angular velocity to update this estimate. The presented system is a first step towards more general odometry systems that could be used for modeling biological navigation systems.

关键词： Neuromorphics Neurons High definition video Navigation Very large scale integration Biological system modeling Brain Neuroscience Cognitive science Educational institutions

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Photonic crystals: A platform for label-free and enhanced fluorescence biomolecular and cellular assays

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MRS Online Proceedings Library 2009年第1期1133卷 1-10页

作者： T. Cunningham Brian Leo Chan C. Mathias Patrick Nikhil Ganesh Sherine George Erich Lidstone James Heeres J. Hergenrother Paul Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana USA Department of Bioengineering University of Illinois at Urbana-Champaign Urbana USA Department of Material Science and Engineering University of Illinois at Urbana-Champaign Urbana USA Department of Chemistry University of Illinois at Urbana-Champaign Urbana USA

Photonic crystal surfaces represent a class of resonant optical structures that are capable of supporting high intensity electromagnetic standing waves with near-field and far-field properties that can be exploited for high sensitivity detection of biomolecules and cells. While modulation of the resonant wavelength of a photonic crystal by the dielectric permittivity of adsorbed biomaterials enables label-free detection, the resonance can also be tuned to coincide with the excitation wavelength of common fluorescent tags - including organic molecules and semiconductor quantum dots. Photonic crystals are also capable of efficiently channeling fluorescent emission into a preferred direction for enhanced extraction efficiency. Photonic crystals can be designed to support multiple resonant modes that can perform label free detection, enhanced fluorescence excitation, and enhanced fluorescence extraction simultaneously on the same device. Because photonic crystal surfaces may be inexpensively produced over large surface areas by nanoreplica molding processes, they can be incorporated into disposable labware for applications such as pharmaceutical high throughput screening. In this talk, the optical properties of surface photonic crystals will be reviewed and several applications will be described, including results from screening a 200,000-member chemical compound library for inhibitors of protein-DNA interactions, gene expression microarrays, and high sensitivity of protein biomarkers.

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LFP beta power predicts cursor stationarity in BMI task

LFP beta power predicts cursor stationarity in BMI task

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2009 4th International IEEE/EMBS Conference on Neural engineering, NER '09

作者： Ranade, Gireeja V. Ganguly, Karunesh Carmena, Jose Department of Electrical Engineering and Computer Sciences University of California Berkeley CA United States Helen Wills Neruoscience Institute University of California Berkeley CA United States Program in Cognitive Science University of California Berkeley CA United States Department of Neurology University of California San Francisco CA United States

ISBN: (纸本)9781424420735

Beta band oscillations in the local field potential (LFP) have been previously related to behavior in motor tasks. We investigated the correlations between beta oscillations and movement state for brain-machine interfaces. Two macaque monkeys were trained to perform a center-out motor task on a computer under normal movement control and under a 'brain control' paradigm, where neural firing directly controls the cursor. In both cases, LFP beta power decreased after movement onset. High beta power was predominantly observed with low movement velocity and vice versa. This observation was used to predict the stationarity of a computer cursor during brain control. ©2009 IEEE.

关键词： Interface states

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Coalition formation through learning in autonomic networks

Coalition formation through learning in autonomic networks

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International Conference on Game Theory for Networks, GameNets

作者： Tao Jiang John S. Baras Institute of Systems Research University of Maryland College Park MD USA Institute of Systems Research Department of Electrical and Computer Engineering Department of Computer Science The Fischell Department of Bioengineering University of Maryland College Park MD USA

Autonomic networks rely on the cooperation of participating nodes for almost all their functions. However, due to resource constraints, nodes are generally selfish and try to maximize their own benefit when participating in the network. Therefore, it is important to study mechanisms, which can be used as incentives for cooperation inside the network. In this paper, the interactions among nodes are modelled as games. A node joins a coalition if it decides to cooperate with at least one node in the coalition. The dynamics of coalition formation proceed via nodes that interact strategically and adapt their behavior to the observed behavior of others. We present conditions that the coalition formed is stable in terms of Nash stability and the core of the coalitional game.

关键词： Costs Game theory Collaborative work Spread spectrum communication Educational institutions Nash equilibrium Communication networks Stability Communication system control Routing

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He ion irradiation damage in Al/Nb multilayers

He ion irradiation damage in Al/Nb multilayers

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作者： Li, Nan Martin, M.S. Anderoglu, O. Misra, A. Shao, L. Wang, H. Zhang, X. Department of Mechanical Engineering Materials Science and Engineering Program Texas A and M University College Station TX 77843-3123 United States Department of Nuclear Engineering Texas A and M University College Station TX 77843-3133 United States Materials Physics and Application Division Los Alamos National Laboratory Los Alamos NM 87545 United States Department of Electrical and Computer Engineering Texas A and M University College Station TX 77843-3128 United States

We investigate the evolution of microstructure and mechanical properties of sputter-deposited Al/Nb multilayers with miscible fcc/bcc type interface and individual layer thickness, h, of 1-200 nm, subjected to helium ion irradiations: 100 keV He+ ions and a fluence of 6 10 16/cm2. Helium bubbles, 1-2 nm in diameter, are observed. When h is greater than 25 nm, hardnesses of irradiated multilayers barely change, whereas radiation hardening is more significant at smaller h. Transmission electron microscopy and scanning transmission electron microscopy studies reveal the formation of a thin layer of Nb3 Al intermetallic phase along the Al/Nb interface as a consequence of radiation induced intermixing. The dependence of radiation hardening on h is interpreted by using a composite model considering the formation of the hard Nb3 Al intermetallic layer. © 2009 American Institute of Physics.

关键词： High resolution transmission electron microscopy

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Image Processing and Modeling for Active Needle Steering in Liver Surgery

Image Processing and Modeling for Active Needle Steering in ...

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International Asia Conference on Informatics in Control, Automation and Robotics, CAR

作者： Bing Nan Li Phu Binh Nguyen S.H. Ong Jing Qin Liang Jing Yang C.K. Chui Graduate Programs in Bioengineering National University of Singapore Singapore Electrical and Computer Engineering National University of Singapore Singapore Computer Science and Engineering Chinese University of Hong Kong Hong Kong China Department of Mechanical Engineering National University of Singapore Singapore

Image-guided intervention and needle steering for radiofrequency ablation (RFA) of the liver is reviewed in this paper. In particular, the concept of active needle is proposed for RFA treatment. Methods and techniques of image processing and modeling are presented for a stereo liver model. The liver model and constituent components extracted from computerized tomography (CT) images can be used to plan the navigation paths of the RFA needle. The system also provides an option for active needles, which are more amenable to those refractory cases of RFA treatment.

关键词： Image processing Needles Surgery Liver neoplasms Biomedical imaging Radio frequency Medical treatment Robotics and automation Computed tomography Visualization

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In-vitro investigations of a pH- and ionic-strength-responsive polyelectrolytic hydrogel using a piezoresistive microsensor

In-vitro investigations of a pH- and ionic-strength-responsi...

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Electroactive Polymer Actuators and Devices (EAPAD) 2009

作者： Schulz, Volker Guenther, Margarita Gerlach, Gerald Magda, Jules J. Tathireddy, Prashant Rieth, Loren Solzbacher, Florian Technische Universitä t Dresden Helmholtzstr. 10 01069 Dresden Germany Department of Materials Science and Engineering 50 South Central Campus Drive Salt Lake City UT 84112 United States Department of Electrical and Computer Engineering 50 South Central Campus Drive Salt Lake City UT 84112 United States Department of Bioengineering University of Utah 50 South Central Campus Drive Salt Lake City UT 84112 United States

ISBN: (纸本)9780819475473

Environmentally responsive or smart hydrogels show a volume phase transition due to changes of external stimuli such as pH or ionic strength of an ambient solution. Thus, they are able to convert reversibly chemical energy into mechanical energy and therefore they are suitable as sensitive material to be integrated in biochemical microsensors and MEMS devices. In this work, micro fabricated silicon pressure sensor chips with integrated piezoresistors were used as transducers for the conversion of mechanical work into an appropriate electrical output signal due to the deflection of a thin silicon bending plate. Within this work two different sensor designs have been studied. The biocompatible poly(hydroxypropyl methacrylate-N, N-dimethylaminoethyl methacrylate-tetra-ethyleneglycol dimethacrylate) (HPMADMA- TEGDMA) was used as an environmental-sensitive element in piezoresistive biochemical sensors. This polyelectrolytic hydrogel shows a very sharp volume phase transition at pH values below about 7.4 which is in the range of the physiological pH. The sensor's characteristic response was measured in-vitro for changes in pH of PBS buffer solution at fixed ionic strength. The experimental data was applied to the Hill equation and the sensor sensitivity as a function of pH was calculated out of it. The time-dependent sensor response was measured for small changes in pH, whereas different time constants have been observed. The same sensor principal was used for sensing the ionic strength. The time-dependent electrical output signal of both sensors was measured for variations in ionic strength at fixed pH value using PBS buffer solution. Both sensor types showed an asymmetric swelling behavior between the swelling and the deswelling cycle as well as different time constants, which was attributed to the different nature of mechanical hydrogel confinement inside the sensor. © 2009 SPIE.

关键词： Microsensors

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