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In this paper, a new mold-transfer method to pattern piezoelectric polymer has been developed and applied to fabricate innovative dome and bump shape polyvinylidenefluoride-trifluoroethylene (PVDF-TrFE) films. The dome and bump shape PVDF-TrFE films have been successfully fabricated and characterized as a sensing component for flexible tactile sensors. The tactile sensors developed using these polymer microstructures show a high sensitivity which can measure as small as 40 mN force for bump shape sensors and 25 mN for dome shape sensors. The newly developed fabrication method provides a flexible way to pattern the piezoelectric polymer with different shapes and dimensions, including bump and dome shape piezoelectric polymer microstructures. In addition, a selective dc poling method for the PVDF-TrFE film has been developed for fabricating precisely located piezoelectric sensors with minimum crosstalk. The bump and dome shape PVDFTrFE films developed in this paper can have numerous applications for microcatheters or other minimally invasive biomedical devices. [2007-0142] Index Terms--Bump shape, dome shape, flexible tactile sensor, mold-transfer method, piezoelectric devices, polyvinylidenefluoride-trifluoroethylene (PVDF-TrFE) piezoelectric copolymer.

This paper reports a new micromachined fluxgate sensor with extremely low power consumption, based on a localized core saturation method. The extremely low power consumption is achieved by quick saturation at the localized core region associated with sensing coils 10 times smaller than the excitation coils. We designed and optimized the sensor by using the electromagnetic simulation software MagNet, and we compared the simulation results with the experimental results. The device exhibits a power consumption of ~14 mW, a sensitivity of 650 V/T at 60 [micro]T, and a sensor span of ~200 [micro]T. In comparison with previously reported micro fluxgate sensors, the newly developed sensor consumes 7 times less power, but at the expense of sensor span and linearity. Index Terms--MEMS, micro fluxgate sensor, microinductor, permalloy film.

A prototype contact-type micro piezoresistive shear-stress sensor that can be utilized to measure the shear stress between skin of stump and socket of above-knee (AK) prosthesis was designed, fabricated and tested. Micro-electro-mechanical system (MEMS) technology has been chosen for the design because of the low cost, small size and adaptability to this application. In this paper, the finite element method (FEM) package ANSYS has been employed for the stress analysis of the micro shear-stress sensors. The sensors contain two transducers that will transform the stresses into an output voltage. In the developed sensor, a 3000 x 3000 x 300 [micro][m.sup.3] square membrane is formed by bulk micromaching of an n-type monolithic silicon. The piezoresistive strain gauges were implanted with boron ions with a dose of [10.sup.15] atoms/[cm.sup.2]. Static characteristics of the shear sensor were determined through a series of calibration tests. The fabricated sensor exhibits a sensitivity of 0.13 mV/mA-MPa for a 1.4 N full scales shear force range and the overall mean hysteresis error is than 3.5%. In addition, the results simulated by FEM are validated by comparison with experimental investigations. [607] Index Terms--Finite element method, micro-electro-mechanical system, piezoresistive, shear-stress sensor, transducer.

Objective: Direct-current electrocorticography (DC-ECoG) allows a more complete characterization of brain states and pathologies than traditional alternating-current recordings (AC-ECoG). However, reliable recording of DC signals is challenging because of electrode polarization-induced potential drift, particularly at low frequencies and for more conducting materials. Further challenges arise as electrode size decreases, since impedance is increased and the potential drift is augmented. While microelectrodes have been investigated for AC-ECoG recordings, little work has addressed microelectrode properties for DC-signal recording. In this paper, we investigated several common microelectrode materials used in biomedical application for DC-ECoG., Approach: Five of the most common materials including gold (Au), silver/silver chloride (Ag/AgCl), platinum (Pt), Iridium oxide (IrOx), and platinum-iridium oxide (Pt/IrOx) were investigated for electrode diameters of 300 μm. The critical characteristics such as polarization impedance, AC current-induced polarization, long-term stability and low-frequency noise were studied in vitro (0.9% saline). The two most promising materials, Pt and Pt/lrOx were further investigated in vivo by recording waves of spreading depolarization, one of the most important applications for DC-ECoG in clinical and basic science research., Main Results: Our experimental results indicate that IrOx-based microelectrodes, particularly with composite layers of nanostructures, are excellent in all of the common evaluation characteristics both in vitro and in vivo and are most suitable for multimodal monitoring applications. Pt electrodes suffer high current-induced polarization, but have acceptable long-term stability suitable for DC-ECoG. Major significance. The results of this study provide quantitative data on the electrical properties of microelectrodes with commonly-used materials and will be valuable for development of neural recordings inclusive of low frequencies.

A novel first-generation Clark-type biosensor platform that can eliminate the oxygen dependence has been presented. Sufficient oxygen to drive the enzymatic reaction under hypoxic conditions was produced by encapsulated oxygen generating biomaterial, calcium peroxide. The catalase immobilized in chitosan matrix was coated on top of the groove to decompose residual hydrogen peroxide to oxygen. A glucose biosensor was developed on the proposed platform as proof of concept. Under hypoxic conditions, developed glucose biosensors maintained their sensitivity response around 84% of their response at oxygen tension of 151 mmHg. The sensitivity deviation was less than 5.3% with the oxygen tension traversed from 0 to 57 mmHg. Under oxygen tension of 8.3 mmHg, the sensitivity of 37.130 nA/mM and the linear coefficient of R(2)=0.9968 were obtained with the glucose concentration varying from 0.05 to 10mM. This new platform is particularly attractive for injured brain monitoring.