Biosensors

Measuring blood hematocrit noninvasively is reviewed in this paper. Although there is an inclination to
measure the hematocrit by determining the bioelectrical impedance of the blood, in vitro experimental
methods still remain practically inapplicable. The blood sample size is determined when blood samples
are examined. Determining the impedance and volume of blood is the biggest challenge in measuring
the hematocrit noninvasively without drawing a blood sample. Calculating the blood impedance in vivo
requires developing an impedance measurement using a multi-frequency method and also calculating
the change in pressure simultaneously during the heart’s pulsatile cycle.

A dimethylferrocene-mediated enzyme electrode for glucose (Cass et al., 1984) was evaluated for application to microbial fermentation monitoring and control. The deficiencies revealed-insufficient stability, progressive increase in response time and progressive decrease in linear range-were investigated using electrochemical and radiochemical techniques. The enzyme immobilization was improved with a novel procedure using periodate-oxidized glucose oxidase and an alkylamine electrode coating. An in-situ probe and a computer-controlled analytical system were developed for fermentation monitoring. The glucose concentration of an Escherichia coli batch culture was successfully monitored on line using this analytical system.

High-level composite, ab initio and density functional theory (DFT) procedures have been employed to study O–H bond dissociation energies (BDEs), as well as radical stabilization energies (RSEs) in the oxygen-centred radicals that are formed in the dissociation of the O–H bonds. Benchmark values are provided by Wn results up to W3.2 and W4.x. We are able to recommend revised BDE values for FO–H (415.6 ± 3 kJ mol–1), MeC(O)O–H (459.8 ± 6 kJ mol–1) and CF3CH2O–H (461.9 ± 6 kJ mol–1) on the basis of high-level calculations. We find that Gn-type procedures are generally reliable and cost-effective, and that some contemporary functionals and double-hybrid DFT procedures also provide adequate O–H BDEs/RSEs. We note that the variations in the O–H BDEs are associated with variations in the stabilities of not only the radicals but also the closed-shell precursor molecules. Most substituents destabilize both species, with σ-electron-withdrawing groups having larger destabilizing effects, whil...

Emotion recognition is one of the important highlights of human emotional intelligence and has long been studied to be incorporated with machine intelligence argued to make machines even more intelligent. This paper aims to contribute to this field of study by enabling machines to recognize emotion from facial electromyogram (EMG) signals. This includes a compilation of the groups attempt to recognize basic facial expressions namely happy, angry, and sad through the use of EMG signals from facial muscles. The group extracted features from the three EMG signals from the face of two human subjects, a male and a female, and analyzed these features to serve as feature templates. Using a minimum-distance classifier, recognition rates exceeded the target accuracy - 85 percent - reaching 94.44 percent for both the male and female subjects.

A potentiometric biosensor based on urease was developed for the quantitative determination of urea concentration in aqueous solutions for biomedical applications. The urease was either physisorbed onto an electrodeposited polyaniline film (PANI), or immobilized on a layer-by-layer film (LbL) assembled over the PANI film, that was obtained by the alternate deposition of charged polysaccharides (carboxymethylpullulan (CMP) and chitosan (CHI)). In the latter case, the urease (Urs) enzyme was either physically adsorbed or covalently grafted to the LbL film using carbodiimide coupling reaction. Potentiometric responses of the enzymatic biosensors were measured as a function of the urea concentration in aqueous solutions (from 10 −6 to 10 −1 mol L −1 urea). Very high sensitivity and short response time were observed for the present biosensor. Moreover, a stability study showed a higher stability over time for the potentiometric response of the sensor with the enzyme-grafted LbL film, testifying for the protective nature of the polysaccharide coating and the interest of covalent grafting.

Genosensor technology relying on the use of carbon and gold electrodes is reviewed. The key steps of each analytical procedure, namely DNA-probe immobilisation, hybridisation, labelling and electrochemical investigation of the surface, are discussed in detail with separate sections devoted to labelfree and newly emerging magnetic assays. Special emphasis has been given to protocols that have been used with real DNA samples.

The pharmaceutical industry is facing enormous challenges due to high drug attribution rates. For the past decades, novel methods have been developed for safety and efficacy testing, as well as for improving early development stages. screening methods for drug-receptor binding are considered to be good alternatives for decreasing costs in the identification of drug candidates. However, these methods require lengthy and troublesome labeling steps. Biosensors hold great promise due to the fact that label-free detection schemes can be designed in an easy and low-cost manner. In this paper, for the first time in the literature, we aimed to compare the potential of label-free optical and impedimetric electrochemical biosensors for the screening of antipsychotic drugs (APDs) based on their binding properties to dopamine receptors. Particularly, we have chosen a currently-used atypical antipsychotic drug (Buspirone) for investigating its dopamine D3 receptor (D3R) binding properties using ...

Geometry of tapered fiber sensors critically affects the response of an evanescent field sensor to cell suspensions. Single-mode fibers (nominally at 1300 nm) were tapered to symmetric or asymmetric tapers with diameters in the range of 3-20 m, and overall lengths of 1-7 mm. Their transmission characteristics in air, water and in the presence of Escherichia coli (JM101 strain) at concentrations of 100, 1000, 7000 and 7 million cells/mL were measured in the 400-800 nm range and gave rich spectral data that lead to the following conclusions. (1) No change in transmission was observed due to E. coli with tapers that showed no relative change in transmission in water compared to air. (2) Tapers that exhibited a significant difference in transmission in water compared to air gave weak response to the presence of the E. coli. Of these, tapers with low waist diameters (6 m) showed sensitivity to E. coli at 7000 cells/mL and higher concentration. (3) Tapers that showed modest difference in water transmission compared to air, and those that had small waist diameters gave excellent response to E. coli at 100-7000 cells/mL. In addition, mathematical modeling showed that: (1) at low wavelength (470 nm) and small waist diameter (6 m), transmission with water in the waist region is higher than in air. (2) Small changes in waist diameter (∼0.05 m) can cause larger changes in transmission at 470 nm than at 550 nm at waist diameter of 6 m. (3) For the same overall geometry, a 5.5 m diameter taper showed larger refractive index sensitivity compared to a 6.25 m taper at 470 nm.

Recently, a novel approach to a highly sensitive and quantitative detection of rare earth element (REE) ions including La3+, Eu3+ and Tb3+, by the polymerase chain reaction (PCR) technique, has been reported. The detection of REE ions is based on the catalytic nature of REE ions targeting the deoxyribonucleic acid (DNA), thus monitoring of the ions can be achieved by reading the level of intact DNA by PCR. Despite of its high sensitivity (at ppb to ppt levels), the conventional PCR-based REE detection protocol requires certain length of time (1-2 hours). In the present study, we modified the PCR-based REE detection protocols by employing the high-speed PCR, and performed the automated and rapid detection of La3+ in small-sized aqueous samples within 5min.

has been developed using L-glutamate oxidase in combination with a hydrogen peroxide indicating electrode. The biosensor response depends linearly on L-glutamate concentrau'on between 0401 and l-0 mM. The measuring time is 2 min. The sensor is stable for more than 10 days during which more than 500 assays can be performed. The sensor has been applied to L-glutamate determination in liquid seasonings. Furthermore, transaminase activities have been determined by their catalytic L-glutamate production from alpha-ketoglutarate and L-alanine or L-aspartate. Also, the coimmobilization of glutaminase yielded a bienzyme electrode sensitive to L-glutamine.

The present work is the first work that includes the use of glycine (Gly), lysine (Lys) and glutamic acid
(Glu) modified clay mineral matrices in the biosensors. For this purpose, initially, Gly, Lys and Glu were
intercalated with montmorillonite (Mt), thus, various modified Mts were obtained. These modified
materials were then characterized via X-ray diffraction, Fourier transform infrared spectroscopy, zeta
potential and thermal gravimetric analysis (TGA/DTG) and scanning electron microscopy (SEM). In order
to investigate the applicability of amino acid modified clay minerals in biosensor area, glucose oxidase
(GOx) was selected as the model enzyme and GOx based biosensor was prepared. After immobilizing the
enzyme with amino acid modified Mt onto a glassy carbon electrode, working conditions like pH and
modifier type were optimized. Among the modified Mts, Gly-Mt was the optimum clay mineral type and
pH 4.0 was the optimum pH value. Then analytical characteristics were examined under optimum
experimental conditions. Linear range of optimum sensor design was 0.1 – 1.0 mM within kinetic
parameters of immobilized enzyme Km
app= 0.7 mM, Imax =107.8 nA. Finally, developed biosensor was
applied to real samples where the results were compared with a spectrophotometric reference method.

This paper describes an action research project based on the process of designing the visualisation of heart and breath rate data for the interactive artwork Cardiomorphologies. The project aimed to realise the affective goals of the artist as closely as possible by studying the audience experience of the visualisations and incorporating the findings into an iterative design process. The qualities of richness and ambiguity were found to contribute to the achievement of the artists' two major aims: 1) to create a sense of ...

The detection of water contamination with Legionella pneumophila is of critical importance to manufacturers of water processing equipment and public health entities dealing with water networks and distribution systems. Detection methods based on polymerase chain reaction or biosensor technologies require preconcentration steps to achieve attractive sensitivity levels. Preconcentration must also be included in protocols of automated collection of water samples by systems designed for quasi-continuous monitoring of remotely located water reservoirs for the presence of L. pneumophila. We designed and characterized a water sampling module for filtration and backwashing intended for analysis of low-to-medium contaminated water, typically with L. pneumophila bacteria not exceeding 50 colony-forming units per milliliter. The concentration factors of 10× and 21× were achieved with 0.22 and 0.45 µm filters, respectively, for samples of bacteria prepared in clean saline solutions. However, a ...

We report an ultracompact label-free biosensor that uses a vertical-cavity surface-emitting laser (VCSEL)-based measurement system for the characterization of biomolecular interactions. It consists of a VCSEL, a plastic guided-mode resonant filter, and two p-in detectors. The system has demonstrated very high sensitivity to molecules on top of the sensor.

Aim. Comparison of the IgG-binding activity of recombinant Staphylococcal protein A with introduced C-terminal cysteine residue (SPA-Cys) or goat anti-human IgG antibodies (anti-IgG) after their immobiliza-tion on a gold sensor surface of surface plasmon resonance (SPR) spectrometer. Methods. SPA-Cys or anti-IgG were immobilized on a gold sensor surface to form two variants of a bioselective element of the immu-nosensor. SPR spectrometry was used for the detection of IgG-binding activity of the immobilized proteins. Results. The SPR sensor response to the immobilization of anti-IgG was more than two times higher than that to the immobilization of SPA-Cys. However, there is almost the double advantage for SPA-Cys in the number of immobilized molecules. Moreover, the bioselective element of the immunosensor based on SPA-Cys showed a much better capability of binding IgG than the bioselective element based on anti-IgG. Conclusions. Comparison of immobilization of SPA-Cys or anti-IgG on the sensor surface of SPR spectrometer, and the interactions of immobilized proteins with human IgG demonstrated obvious advantages of SPA-Cys. K e y w o r d s: antibodies, recombinant Staphylococcal protein A, protein immobilization, immunosensor, surface plasmon resonance.

This paper presents a micromagnetoelastic sensor array for simultaneously monitoring multiple biological agents. Magnetoelastic sensors, made of low-cost amorphous ferromagnetic ribbons, are analogous and complementary to piezoelectric acoustic wave sensors, which track parameters of interest via changes in resonance behavior. Magnetoelastic sensors are excited with magnetic ac fields, and, in turn, they generate magnetic fluxes that can be detected with a sensing coil from a distance. As a result, these sensors are highly attractive, not only due to their small size and low cost, but also because of their passive and wireless nature. Magnetoelastic sensors have been applied for monitoring pressure, temperature, liquid density, and viscosity, fluid flow velocity and direction, and with chemical/biological responsive coatings that change mass or elasticity, various biological and chemical agents. In this paper, we report the fabrication and application of a six-sensor array for simultaneous measurement of Escherichia coli O157:H7, staphylococcal enterotoxin B, and ricin. In addition, the sensor array also monitors temperature and pH so the measurements are independent from these two parameters.

The possibility of employing graphene sheets as a potential candidate for the construction of biofuel cells is reported in this paper. Initially, graphene sheets were chemically synthesized and characterized by surface characterization techniques. Following this, graphene was employed to fabricate the anode and cathode in the biofuel cell. The anode of the biofuel cell consists of a gold electrode on which we co-immobilized graphene -glucose oxidase using silica sol-gel matrix. Voltammetric measurements were conducted to quantitatively evaluate the suitability of employing graphene sheets as an electrode dopant and its performance was compared with single walled carbon nanotubes (SWCNTs). The cathode of the biofuel cell was constructed in a similar method except that graphene was co-immobilized with bilirubin oxidase. Finally, two membraneless enzymatic biofuel cells, one using graphene sheets and the other using SWCNTs, were constructed and their performances were compared. Upon comparison, graphene based biofuel cell exhibited a maximum power density of about 24.3 ± 4 W (N = 3), which is nearly two times greater than that of the SWCNTs biofuel cell, and the performance of the graphene biofuel cell lasted for 7 days.

In this paper, we propose to introduce the selfesteem component within learning process. More precisely, we explore the effects of learner self-esteem conditioning in a tutoring system. Our approach is based on a subliminal priming method aiming at enhancing implicit self-esteem. An experiment was conducted while participants were outfitted with biofeedback device. Three physiological sensors were used to continuously monitor learners' affective reactions namely electroencephalogram, skin conductance and blood volume pulse sensors. The purpose of this work is to analyze the impact of self-esteem conditioning on learning performance on one hand and learners' emotional and mental states on the other hand.

Glucose sensors are potentially useful tools for monitoring the glucose concentration in cell culture medium. Here, we present a new, low-cost, and reproducible sensor based on a cellulose-based material, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized-cellulose nanocrystals (CNCs). This novel biocompatible and inert nanomaterial is employed as a polymeric matrix to immobilize and stabilize glucose oxidase in the fabrication of a reproducible, operationally stable, highly selective, cost-effective, screen-printed glucose sensor. The sensors have a linear range of 0.1–2 mM (R2 = 0.999) and a sensitivity of 5.7 ± 0.3 µA cm−2∙mM−1. The limit of detection is 0.004 mM, and the limit of quantification is 0.015 mM. The sensor maintains 92.3 % of the initial current response after 30 consecutive measurements in a 1 mM standard glucose solution, and has a shelf life of 1 month while maintaining high selectivity. We demonstrate the practical application of the sensor by monitoring the g...

Aquaculture is globally the fastest growing primary industry (>6% per annum). Smart-farming, using sentinel animals equipped with miniature biosensors alongside environmental sensors and farm management systems has the potential to revolutionize all sectors of the industry. Real-time animal and environmental monitoring together, will support improved farm management decisions, animal welfare, social awareness and consequently sustainable productivity. Biosensors that monitor the physiology and behavior of sentinel animals provide information on animal well-being and its responses to environmental change and management actions. In turn, this information is extrapolated to help with stock management decisions. This paper introduces the sentinel animal concept to commercial aquaculture with a case study using oysters fitted with biosensors that measure heart rate, and other parameters. We demonstrate how sentinel animals can be effectively integrated alongside environmental sensors ...

We describe the development of polycrystalline silicon piezoresistive micro/nanocantilevers for the measurement of intermolecular forces in biochemical sensing. The cantilevers have been fabricated both in a dedicated technology and in a commercial CMOS technology with an additional micromachining postprocessing. The sensitivity and resolution required by the application are achieved with cantilevers with submicrometer thickness and width in the micrometer range. The cantilevers have been successfully tested by applying a known displacement with an AFM, obtaining a value of 12 for the gauge factor.

The advances in studies of trace metal speciation and bioavailability since Mark Florence’s 1982 review of the topic, published in Talanta, have been comprehensively reviewed. While the relative merits of kinetic and equilibrium approaches are still being determined, advances in the applications of stripping voltammetry, including the application of microelectrodes and an appreciation of detection windows in both CSV and ASV, have been matched by the introduction of new dynamic techniques including diffusive gradients in thin films (DGTs), permeation liquid membranes (PLMs), and improved applications of chelating resins. There have also been improvements in equilibrium techniques such as ion-selective electrodes and Donnan dialysis. The ability of geochemical speciation models to predict metal complexation by natural organic matter has greatly improved, yet the models still require validation against field measurements. More reliable and relevant bioassays have been developed using ...

The use of volatile production patterns produced by bacterial contaminants in urine samples were examined using electronic nose technology. In two experiments 25 and 45 samples from patients were analysed for specific bacterial contaminants using agar culture techniques and the major UTI bacterial species identified. These samples were also analysed by incubation in a volatile generation test tube system for 4 Á/5 h. The volatile production patterns were then analysed using an electronic nose system with 14 conducting polymer sensors. In the first experiment analysis of the data using a neural network (NN) enabled identification of all but one of the samples correctly when compared to the culture information. Four groups could be distinguished, i.e. normal urine, Escherichia coli infected, Proteus spp. and Staphylococcus spp. In the second experiment it was again possible to use NN systems to examine the volatile production patterns and identify 18 of 19 unknown UTI cases. Only one normal patient sample was mis-identified as an E. coli infected sample. Discriminant function analysis also differentiated between normal urine samples, that infected with E. coli and with Staphylococcus spp. This study has shown the potential for early detection of microbial contaminants in urine samples using electronic nose technology for the first time. These findings will have implications for the development of rapid systems for use in clinical practice. #

Various berries and fruit types of less common fruit species are known to contain antioxidants. Consumption of high amounts of antioxidant flavonoids, which display a variety of biological properties, including antiproliferative and anti-inflammatory activity, may have a positive impact on human health, particularly for the prevention of cancer and other inflammatory diseases. In these studies, based on the hypothesis that the fruit extract with the highest content would possess significantly higher health benefits, flavonoid-rich extracts were obtained from some less common fruit species -Blue Honeysuckles (Lonicera Kamtschatica and Lonicera edulis, Turcz. ex. Freyn), Saskatoon berry (Amelanchier alnifolia Nutt.) and Chinese Hawthorn (Crataegus pinnatifida BUNGE) -grown from germplasm held at the Mendel University of Agriculture and Forestry in Brno, Czech Republic and then characterized in terms of biological value based on the results from a relative antioxidant capacity assessment. The antioxidant content

A brief overview of acoustic wave sensor physics, materials, sensor types, and applications is presented in this paper. Emphasis is placed on the different types of acoustic wave sensors, their respective advantages, and their specific applications in industry.

While place-based methods are increasingly being used to explore why place matters for health, how places matter for mental health and psychological wellness is less understood. Overall, approaches that consider community, environmental, and neighborhood-level factors have been taken up to a lesser extent by psychologists. Yet methods that situate human behavior within a spatial context have the potential to expand psychological and interdisciplinary inquiry aimed at improving mental and cognitive health. This article presents a brief overview of one type of mobile method, the go-along walk, that can be used with a variety of technologies and complementary methods to better understand how individuals respond to places and environmental stimuli, including place-based exposures. Implications for broadening the range of research questions and translational applications are discussed.

Iron deficiency (ID) is an urgent public health problem that has devastating effects on maternal and child health. However, due to poor access and affordability, screening and diagnosis for ID is often limited to proxy hemoglobin measurements alone. Here, we report the development and validation of ironPhone, a mobile-device coupled portable diagnostics for quantification of serum ferritin concentrations, an iron status biomarker, within a few minutes, from a drop of fingerprick blood. The ironPhone diagnostic platform comprises of a smartphone accessory, an app, and a disposable lateral flow immunoassay test strip to quantify serum ferritin. For initial validation in the lab, we optimized and evaluated the performance of ironPhone with known ferritin concentrations in spiked buffer and serum samples. Following lab validation, we performed a human validation by collecting fingerprick whole blood samples from 20 participants to assess iron status using ironPhone and compared the results with the laboratory standard IMMULITE 2000 analyzer. Findings from the ironPhone for the buffer and spiked serum samples provided a calibration curve with R 2 values of 0.97 (n=27) and 0.93 (n=12), respectively. On comparison with the laboratory standard IMMULITE analyzer in whole blood samples, a correlation of 0.92 (P < 0.0001) was observed with a sensitivity of over 90% for predicting ID (ferritin < 15.0 µg/L) via the ironPhone, demonstrating its promise for iron status assessment at the point-of-care.

Part of designing any system requires the development of an architecture on which the system and subsequent implementations are based. The architecture will vary depending on the requirements. For a healthcare monitoring application the researchers developed a four-tiered architecture that consists of the following layers: user interface, process management, database and sensor network. In this paper, the authors present their layered architecture for remote healthcare monitoring of aged and infirm persons and illustrate its advantages by describing their latest prototype which is called MoteCare. They also discuss the direction the researchers intend to take for the development of their fourth prototype, paying particular attention to the use of open source databases, the issue of security in the development of mote sensor networks (MSN) and the advantages of linking such systems with wireless broadband to enable potential users to achieve more mobility options.

The feasibility of a biosensor for DNA detection based on suspended-core photonic crystal fibers is investigated. The possibility of functionalization of the hole surface, which allows DNA strand binding, is demonstrated, along with the selective detection of DNA through hybridization of immobilized peptide nucleic acid probes with their full-complementary and mismatched DNA segments. Index Terms-Biosensor, DNA, peptide nucleic acid (PNA), photonic crystal fiber (PCF).

Bulk characteristics and deposition of gold nanoparticles on mica modified by (PAH) was studied byUV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM),dynamic light scattering (DLS) and atomic force microscopy (AFM). The size of gold nanoparticles (AuNPs)was 15 nm as determined by TEM and AFM. The electrophoretic mobilities and electrokinetic chargeof particles were quantitatively evaluated for a broad range of pH and ionic strength. Using Henry’smodel, it was calculated that the zeta potential of particles varied between − 50 mV and − 80 mV forpH 2 and pH 11, respectively (at 10−2M of NaCl). Measurements of nanoparticle deposition kineticswere performed under diffusion-controlled transport conditions using AFM and SEM imaging of particlemonolayers. The influence of the bulk suspension concentration was systematically studied. Additionally,the maximum coverage of particle monolayers, which monotonically increased with ionic strength, wasdetermined by SEM. The obtained data were in agreement with theoretical predictions derived from therandom sequential adsorption (RSA) model. It was also confirmed that by varying the bulk suspensionconcentration and ionic strength one can prepare homogeneous gold particle monolayers of controlledcoverage.

An amperometric peroxide biosensor was prepared by electrochemical deposition of horseradish peroxidase (HRP) on a Pt disc electrode modified with polyaniline (PANI) film doped with polyvinyl sulphonate (PVS). Electrochemical characterisation of the PANI-PVS film (without HRP) indicates a conducting electroactive polymer that exhibits fast reversible electrochemistry in 1 M HCl. The HRP-based sensor was stable and gave rise to reproducible steady state responses for up to two weeks, when operated as both organic phase and aqueous phase H 2 O 2 biosensors at -100 mV/Ag-AgCl and 25°C. The aqueous phase for the H 2 O 2 assay was 0·05 M phosphate buffer, pH 6·88, while acetone, acetonitrile, propan-2-ol and tetrahydrofuran (THF) organic phases were used. The analyses of the calibration curves of the biosensor showed that the system followed a Michaelis-Menten kinetics when operated either as organic-or aqueous-phase biosensors. The kinetic parameters K m Ј (apparent Michaelis-Menten constant), k cat Ј (apparent biosensor turnover rate constant), and k cat Ј/K m Ј biosensing efficiency parameter) were evaluated from the steady-state amperometric data obtained in the five solvent media. The values of the biosensor efficiency factor, k cat Ј/K m Ј, show that the sensor exhibits greater efficiency for analyte detection when operated in organic-phase mode in acetonitrile medium than in aqueous buffer. ©1997 Elsevier Science Limited Keywords: polyaniline based biosensor, organic phase biosensor, organic phase enzyme electrode, peroxide sensor, polyaniline film doped with poly(vinylsulphonate), kinetics of organic phase horseradish peroxidase electrode

Phenol and several phenol derivatives have been electropolymerised on to platinum anodes. The selective properties of the modified electrodes were dependent on the final polymeric structure. Although essentially nonconducting, dual phenolic films could be deposited on electrode surfaces. This was achieved by the initial deposition of a porous polymer formed from, phenol red, followed by the more diffusion limiting film of oxidised phenol. The resulting composite film showed the combined selective characteristics of the two component polymers. Attempts to enhance polymeric film selectivity via the incorporation of charged or neutral surfactants are outlined. The characteristics of glucose oxidase incorporated into (poly)phenol films are discussed.

Wireless biosensor applications require RF electronics to operate in immediate proximity of the body. This work investigates the effect of human body on RF circuits by simulations and measurements. Design methodology and initial design guidelines for body-worn discrete RF electronics are presented. The test structures are manufactured using printed electronics technology well suited for thin, flexible body-worn wireless sensor applications. The results indicate that in direct contact the human body significantly affects the performance of an RF circuit and needs to be considered. The research is relevant for modeling-based design of flexible body-worn wireless sensors.

In order to protect implanted glucose sensors from biofouling, novel hydrogels (146-217% water by mass) were developed based on a copolymer of hydroxyethyl methacrylate (HEMA) and 2,3-dihydroxypropyl methacrylate (DHPMA). The porosity and mechanical properties of the hydrogels were improved using N-vinyl-2-pyrrolidinone (VP) and ethyleneglycol dimethacrylate (EGDMA). The results of SEM and DSC FT-IT analyses showed that the hydrogel (VP30) produced from a monomeric mixture of 34.5% HEMA, 34.5% DHPMA, 30% VP and 1% EDGMA (mol%) had an excellent pore structure, high water content at swelling equilibrium (W eq = 166% by mass) and acceptable mechanical properties. Two kinds of VP30-coated sensors, Pt/GOx/VP30 and Pt/GOx/epoxy-polyurethane (EPU)/VP30 sensors were examined in glucose solutions during a period of 4 weeks. The Pt/GOx/VP30 sensors produced large response currents but the response linearity was poor. Therefore, further studies were focused on the Pt/GOx/EPU/VP30 sensors. With a diffusion-limiting epoxy-polyurethane membrane, the linearity was improved (2-30 mM) and the response time was within 5 min. Eight Pt/GOx/EPU/VP30 sensors were subcutaneously implanted in rats and tested once per week over 4 weeks. All of the implanted sensors kept functioning for at least 21 days and 3 out of 8 sensors still functioned at day 28. Histology revealed that the fibrous capsules surrounding hydrogel-coated sensors were thinner than those surrounding Pt/GOx/EPU sensors after 28 days of implantation.

With the incorporation of lysozyme during the immobilization step, considerable enhancement of the operational stability of a biosensor has been demonstrated in the case of an immobilized single enzyme (glucose oxidase) system for glucose and multienzyme (invertase, mutarotase and glucose oxidase) system for sucrose. Thus an increased number of repeated analyses of 750 samples during 230 days for glucose and 400 samples during 40 days of operation for sucrose have been achieved. The increased operational stability of immobilized single and multienzyme system, will improve the operating cost effectiveness of the biosensor. #

Biosensors are being used for highly sensitive and selective recognition of biological macromolecules. The impedance based biosensor utilizes the electrical impedance measurements between interdigitated electrodes integrated into a microchannel containing the target cells in a suspension medium. The detection is based on measuring the change in impedance caused by the presence of bacteria. In the experimental methods an impedance analyzer was used to measure the electrical impedance. The first impedance measurement was done with the microfluidic system containing the suspension medium alone and is referred to as the control signal. The subsequent impedance measurements were performed with known concentration of Escherichia coli (E. coli) cells added to the same suspension medium. In this paper we describe the simulation of impedance measurements using the electromagnetics module of COMSOL Multiphysics TM , a commercially available modeling package.

In body biosensor networks, which may be classified as a specialized type of ad hoc networks, it is necessary to ensure the authenticity and freshness of the vital medical information. In this work, we propose security solutions to identify attacks on data freshness and preserve message integrity in these networks. We use the measurement of permissible round trip time threshold and computationally feasible authentication solution to address the security threats in the network. We have implemented a prototype framework in GloMoSim to assess and evaluate the robustness of our detection mechanism.