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Layer-by-layer assembled semipermeable membrane for amperometric glucose sensors

Journal of Diabetes Science and Technology 2007年第2期1卷 193-200页

作者： Tipnis, Ritesh Vaddiraju, Santhisagar Jain, Faquir Burgess, Diane J. Papadimitrakopoulos, Fotios Nanomaterials Optoelectronics Laboratory Polymer Program University of Connecticut Storrs CT 06269 United States Nanomaterials Optoelectronics Laboratory Electrical and Computer Engineering University of Connecticut Storrs CT United States Department of Pharmaceutical Sciences University of Connecticut Storrs CT United States Department of Chemistry University of Connecticut Storrs CT United States

Background: The performance of implantable glucose sensors is closely related to the behavior of the outer membrane. Such membranes govern the diffusion characteristics of glucose and, correspondingly, the sensitivity of the sensors. This manuscript discusses the selection of various membrane materials and their effect on the device response. Methods: Sensors were fabricated utilizing a 50-μm platinum wire followed by immobilization of the glucose oxidase (GOx) enzyme. Sequential adsorption of various ionic species via a layer-by-layer process created devices coated with bilayers of humic acids/ferric cations (HAs/Fe³⁺), humic acids/ poly(diallyldimethylammonium chloride) (HAs/PDDA), and poly(styrene sulfonate)/poly(diallyldimethylammonium chloride) (PSS/PDDA). The in vitro amperometric response of the sensors was determined at 0.7 V vs an Ag/AgCl reference electrode in phosphate-buffered saline (37°C) for various glucose concentrations. The diffusion coefficients of glucose and hydrogen peroxide (H2O2) through these membranes were calculated and analyzed. Results: Outer membranes based on the sequential deposition of bilayers of H As/Fe³⁺, HAs/PDDA, and PSS/PDDA were grown successfully on immobilized layers of GOx. The amperometric response and reversibility upon changing the in vitro concentration of glucose were investigated. Conclusions: Through alteration of the number of bilayers of the outer membrane, it was possible to modulate the diffusion of glucose toward the sensor as a result of its flux-limiting characteristics. Semipermeable membranes based on five HAs/Fe³⁺ bilayers exhibited a superior behavior with a minimum hysterisis response to glucose cycling and a lesser current saturation at hyperglycemic glucose concentrations because of a more balanced inward diffusion of glucose and outward diffusion of H2O2. © Diabetes Technology Society.

关键词： biosensors outer membrane layer by layer assembly humic acids diffusion through membranes

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A Method to Realize Controlled Air/Liquid Interfaces and Interfacial Polymer Micro Membranes in Microfluidic Channels

A Method to Realize Controlled Air/Liquid Interfaces and Int...

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IEEE SENSORS

作者： Daming Cheng YoungJoon Paul Choe Hongrui Jiang Department of Electrical and Computer Engineering University of Wisconsin Madison Madison USA Department of Electrical and Computer Engineering University of Wisconsin Madison Madison WI USA Materials Science Program University of Wisconsin-Madison USA Department of Electrical and Computer Engineering University of Wisconsin-Madison Madison WI. Email: hongrui@engr.wisc.edu

In this study, stable air/liquid interfaces and high-aspect ratio polymer micro membranes with complex and controlled structures were formed within microfluidic channels. The air/liquid interfaces were formed at hydrophilic/hydrophobic boundaries defined by patterned and alkanethiols treated Cu surfaces. The two-phase interfaces were further utilized for interfacial polymerization with two immiscible liquid phases containing the reagents for polymer membrane in the microchannel, to generate polymer micro membranes with not only complex in-plane shapes but also z-direction configurations. To demonstrate this method, high quality and complex nylon membranes were fabricated in microchannels. Straight membranes as long as 15mm, 50 mum thick and 500 mum tall in a microfluidic channel were successfully fabricated, and membranes with different structures were realized.

关键词： Polymers Biomembranes Microfluidics Surface treatment Glass Microchannel Shape Materials science and technology Chemical processes Gold

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Improved retention through innovative academic and non-academic programs

Improved retention through innovative academic and non-acade...

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114th Annual ASEE Conference and Exposition, 2007

作者： Mathias, James Gupta, Lalit Nicklow, John Tezcan, Jale Caffey, Ronald Chrisman, Bruce Pearson, Chris Pericak-Spector, Kathy Kowalchuk, Rhonda Lewis, Ernest Sevim, Hasan Southern Illinois University Carbondale United States United States Department of Electrical and Computer Engineering Southern Illinois University Carbondale IL United States ECE Department ABET Review Committee College of Engineering Faculty Mentoring Program IEEE United States Department of Civil and Environmental Engineering United States United States United States United States United States Southern Illinois University Edwardsville United States School of Engineering SIU

In conjunction with a grant from the National Science Foundation, the retention of students in Southern Illinois University - Carbondale (SIUC) College of engineering will be increased through the introduction of innovative academic and non-academic programs. The new academic programs consist of the following components: an introduction to engineering course, engineering designated sections of courses, a summer math course for new students who need improvement in math, and revisions to the math curriculum. The new non-academic programs consist of: creation of an engineering residential college, and peer mentoring, faculty mentoring, and mentoring by practicing engineers. The introduction to engineering course will include all freshman students in SIUC College of engineering. This lecture-laboratory course will provide an interesting description of each engineering major and allows students to work with hands-on projects that will teach the usefulness of mathematics and basic engineering concepts. The SIUC College of engineering has worked with other departments on campus to offer engineering designated sections of core curriculum courses, such as math, sciences, English, and speech communication. The summer math course lasts four-weeks and accepts students who test below the pre-calculus level and prepares them for pre-calculus during the fall semester. The mathematics curriculum is being modified so that all students who do not test into calculus will take a math course taught by the college of engineering that prepares them for calculus. Also, there are non-academic programs that have been designed to improve retention and the freshman experience. First, to foster the "living-learning community" experience, all freshman and sophomore engineering students will live in the engineering residential college with 36 peer mentors and three residential assistants. The engineering residential college also houses a classroom where engineering designated sections of common c

关键词： engineering education

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New Neurofuzzy Training Procedure Based on Participatory Learning Paradigm

New Neurofuzzy Training Procedure Based on Participatory Lea...

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IEEE International Conference on Fuzzy Systems (FUZZ-IEEE)

作者： Michel Hell Pyramo Costa Fernando Gomide Department of Computer Engineering and Automation (DCA) Faculty of Electrical and Computer Engineering (FEEC) State University of Campinas Sao Paulo Brazil Graduate Program in Electrical Engineering Pontifical Catholic University of Minas Gerais Belo Horizonte Minas Gerais Brazil

In this paper we introduce a new approach to train neurofuzzy networks using the participatory learning concept. The participatory learning paradigm tends to emulate the human learning mechanism where an acceptance mechanism determines which observation is used for learning based upon their compatibility with the current beliefs. The performance of the proposed learning scheme is illustrated by an example involving a nonlinear system modeling problem: the thermal modeling of power transformers. Comparisons with other methods reported in the literature and between two dual network structures are also included. The experimental results show the effectiveness of participatory learning in neurofuzzy networks training.

关键词： Power system modeling Fuzzy systems Power transformers Training data Humans Nonlinear systems Neural networks Fuzzy sets Power engineering computing Power engineering and energy

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Development of a Wireless Capacitive Sensor for Ambulatory ECG Monitoring over Clothes

Development of a Wireless Capacitive Sensor for Ambulatory E...

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29th Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBS 2007), vol.14

作者： Yoshihiro Yama Akinori Ueno Yoshinori Uchikawa Masters Program in Electronic and Computer Engineering Tokyo Denki University Hatoyama Saitama Japan Department of Electrical and Electronic Engineering Tokyo Denki University Tokyo Japan Department of Electronic and Computer Engineering Tokyo Denki University Saitama Japan

We present a wireless capacitive sensor for ambulatory ECG monitoring. The device is capable of detecting electrocardiographic potential through underwear. It is based on capacitive coupling involving the electrode, the underwear, and the skin. Validation of the system revealed the following: (1) The frequency response of the device with the underwear revealed that the gain of the detected signal was reduced, but distortion of the signal within the pass-band (from 6 to 45 Hz) was minimal even with the underwear. (2) The signal displayed a periodic waveform synchronized with the simultaneously recorded ECG, even when the underwear was inserted between the electrode and the skin. (3) Although the signal was seemed deteriorated slightly while walking, R-waves were recognized easily. Although there is still room for improvement in terms of its practical use, the proposed approach appears promising for application to ambulatory ECG monitoring.

关键词： Wireless sensor networks Capacitive sensors Electrocardiography Monitoring Electrodes Skin Frequency response Signal detection Distortion Frequency synchronization

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Contributors to the Lab on a Chip cell and tissue engineering in microsystems special issue

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Lab on a Chip 2007年第6期7卷 667-671页

作者： Bhatia, Sangeeta N. Chen, Christoper Bashir, Rashid Beebe, David J. Desai, Tejal Gottwald, Eric Khademhosseini, Ali Langer, Robert S. Piel, Matthieu Takayama, Shuichi Thorsen, Todd Tien, Joe Voldman, Joel Vunjak-Novakovic, Gordana Wu, Mingming Yu, Hanry Massachusetts Institute of Technology Harvard-MIT Division of Health Sciences and Technology Department of Electrical Engineering and Computer Science United States Laboratory for Multiscale Regenerative Technologies United States Department of Innovation University of Pennsylvania Department of Bioengineering United States Cell Biology and Physiology Program Cell Growth and Cancer Program Tissue Microfabrication Laboratory Department of Electrical and Computer Engineering and Biomedical Engineering Purdue University United States Department of Electronics University of Glasgow United Kingdom Department of Physiology and Bioengineering University of California San Francisco CA United States California Institute for Quantitative Biomedical Research UCSF/UC Berkeley Graduate Group in Bioengineering United States Laboratory of Therapeutic Micro and Nanotechnology Institute for Biological Interfaces Germany 3D-Cell Culture Techniques Group Institute for Biological Interfaces Germany Department of Medicine and Health Sciences and Technology Massachusetts Institute of Technology (MIT) United States Institut Curie UMR 144 IC/CNRS France Biomedical Engineering Department University of Michigan United States Department of Biomedical Engineering Macromolecular Science and Engineering Program United States Sibley School of Mechanical and Aerospace Engineering School of Chemical and Molecular Engineering Cornell University United States National University of Singapore Singapore Institute of Bioengineering and Nanotechnology A STAR Singapore

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Mentoring interdisciplinary service learning projects

Mentoring interdisciplinary service learning projects

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Frontiers in Education (FIE) Conference

作者： Efrain O'Neill-Carrillo Luisa Seijo Francisco Maldonado E. Dan Hirleman Edgar Marti Alix Rivera Electrical and Computer Engineering Department University of Puerto Rico-Mayagüez Department of Social Sciences University of Puerto Rico-Mayagüez USA Department of Civil Engineering University of Puerto Rico-Mayagüez USA Global Engineering Program Purdue University USA Electrical and Computer Engineering Department University of Puerto Rico-Mayagüez Puerto Rico

The University Institute for Community Development (UICD) at the University of Puerto Rico- Mayagiiez (UPRM) has been involved in service learning projects with communities in Puerto Rico since 2002. Every semester, over 200 students from over 20 disciplines work in partnerships with community leaders to address and further the communities' work agendas. Faculty mentors are a key component in the IUDC. They provide guidance in both technical and non-technical issues related to each project. They supervise the progress of students and communicate with community leaders throughout the semester. Student mentoring can occur at different levels: discipline, sub-group and larger group. This three- pronged approach is essential to mentor interdisciplinary teams. This paper presents an overview of the UICD its service philosophy, and the mentoring process involved. It also presents an example of a course and a project where service learning was integrated, and some of the challenges in mentoring an interdisciplinary team of students.

关键词： Employee welfare Educational institutions Investments Cultural differences Global communication Space vehicles Transportation

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Digital signal processing, theory and practical considerations

Digital signal processing, theory and practical consideratio...

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114th Annual ASEE Conference and Exposition, 2007

作者： Mousavinezhad, S. Hossein Dong, Liang Western Michigan University United States IEEE ASEE IEEE Region 4 Educational Activities ASEE North Central Section Executive Board ECE Department Western Michigan University United States ABET Program Department of Electrical and Computer Engineering Phi Kappa Phi Sigma Xi United States Tau Beta Pi United States

Digital Signal Processing (DSP) is an important and growing subject area within electrical and computer engineering (and also computer science). With the availability of "powerful" tools, software packages and hardware/software systems for use in DSP courses, we need to be careful and use professional judgment as to where/when to use and introduce these teaching aids and tools. The authors have taught both graduate and undergraduate DSP and real-time systems courses, established industry-certified laboratory in the home university where students can do projects without the actual experiments in lecture-only courses. Even "DSP on wheels" concept was used in an attempt to show some practical applications of the subject matter. But students still consider the subject to be highly mathematical and maybe too much on the theoretical side. In this paper we will show some examples of actual classroom projects, homework assignments trying to present a balance between theory and practice. With term projects and papers to be submitted, we have also used electronic (web-based) portfolio system so that project reports and documentation can be uploaded, then instructor can go online and review the work and submit feedback and assessment to the student. There is also a good collection of textbooks available in the DSP for both undergraduates and graduate students, these are fairly recent texts but because of the inclusion of more simulation type examples maybe theory and underlying principles are being left out. Again the question of balance between theory and practice comes up for discussion among engineering educators. There are a few examples in the paper (mainly using MATLAB and MATHCAD) to show the tradeoffs and importance of understanding the theory and logic for the students before they attempt using computational routines and simulation programs. A discussion needs to be started on the actual time of offering a DSP course in the curriculum (before or after circuits?), how

关键词： Signal processing

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Lattice Boltzmann algorithms for fluid turbulence

Lattice Boltzmann algorithms for fluid turbulence

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department of Defense - HPCMP Users Group Conference 2007;High Performance Computing Modernization program: A Bridge to Future Defense, DoD HPCMP UGC

作者： Vahala, George Yepez, Jeffrey Soe, Min Vahala, Linda Ziegeler, Sean Department of Physics College of William and Mary Williamsburg VA United States Hanscom Field MA United States Department of Mathematics and Science Rogers State University Claremore OK United States Department of Electrical and Computer Engineering Old Dominion University Norfolk VA United States High Performance Computing Modernization Program Mississippi State University MS United States

ISBN: (纸本)0769530885

Lattice Boltzmann algorihms are a mesoscopic representation of nonlinear continuum physics (like Navier-Stokes, magnetohydrodynamics (MHD), Gross-Pitaevskii equations) which are ideal for parallel supercomputers because they transform the difficult nonlinear convective macroscopic derivatives into purely local moments of distribution functions. The macroscopic nonlinearities are recovered by relaxation distribution functions in the collision operator whose dependence on the macroscopic velocity is algebraically nonlinear and thus purely local. Unlike standard computational fluid dynamics codes, there is no loss in parallelization in handling arbitrary geometric boundaries, e.g., using bounce-back rules from kinetic theory. By encoding detailed balance into the collision operator through the introduction of discrete H-function, the lattice Boltzmann algorithm can be made unconditionally stable for arbitrary high Reynolds numbers. It is shown that this approach is a special case of a quantum lattice Boltzmann algorithm that entangles local qubits through unitary collision operators and which is ideally parallelized on quantum computer architectures. Here we consider turbulence simulations using 2,048 PEs on a 1,6003-spatial grid. A connection is found between the rate of change of enstrophy and the onset of laminar-to-turbulent flows. © 2007 IEEE.

关键词： Magnetohydrodynamics

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Using pitch, amplitude modulation, and spatial cues for separation of harmonic instruments from stereo music recordings

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Eurasip Journal on Advances in Signal Processing 2007年 2007卷

作者： Woodruff, John Pardo, Bryan Music Technology Program School of Music Northwestern University Evanston IL 60208 United States Department of Electrical Engineering and Computer Science Northwestern University Evanston IL 60208 United States

Recent work in blind source separation applied to anechoic mixtures of speech allows for improved reconstruction of sources that rarely overlap in a time-frequency representation. While the assumption that speech mixtures do not overlap significantly in time-frequency is reasonable, music mixtures rarely meet this constraint, requiring new approaches. We introduce a method that uses spatial cues from anechoic, stereo music recordings and assumptions regarding the structure of musical source signals to effectively separate mixtures of tonal music. We discuss existing techniques to create partial source signal estimates from regions of the mixture where source signals do not overlap significantly. We use these partial signals within a new demixing framework, in which we estimate harmonic masks for each source, allowing the determination of the number of active sources in important time-frequency frames of the mixture. We then propose a method for distributing energy from time-frequency frames of the mixture to multiple source signals. This allows dealing with mixtures that contain time-frequency frames in which multiple harmonic sources are active without requiring knowledge of source characteristics. Copyright © 2007 Hindawi Publishing Corporation. All rights reserved.

关键词： Harmonic generation

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