Low-cost photolithographic fabrication of nanowires and microfilters for advanced bioassay devices.

Integrated microfluidic devices with nanosized array electrodes and microfiltration capabilities can greatly increase sensitivity and enhance automation in immunoassay devices. In this contribution, we utilize the edge-patterning method of thin aluminum (Al) films in order to form nano- to micron-sized gaps. Evaporation of high work-function metals (i.

Enhancing the sensitivity of needle-implantable electrochemical glucose sensors via surface rebuilding.

Objective: Needle-implantable sensors have shown to provide reliable continuous glucose monitoring for diabetes management. In order to reduce tissue injury during sensor implantation, there is a constant need for device size reduction, which imposes challenges in terms of sensitivity and reliability, as part of decreasing signal-to-noise and increasing layer complexity. Herein, we report sensitivity enhancement via electrochemical surface rebuilding of the working electrode (WE), which creates a three-dimensional nanoporous configuration with increased surface area.

Effect of dexamethasone-loaded poly(lactic-co-glycolic acid) microsphere/poly(vinyl alcohol) hydrogel composite coatings on the basic characteristics of implantable glucose sensors.

Background: Hydrogels alone and in combination with microsphere drug delivery systems are being considered as biocompatible coatings for implantable glucose biosensors to prevent/minimize the foreign body response. Previously, our group has demonstrated that continuous release of dexamethasone from poly(lactic-co-glycolic acid) (PLGA) microsphere/poly(vinyl alcohol) (PVA) hydrogel composites can successfully prevent foreign body response at the implantation site. The objective of this study was to investigate the effect of this composite coating on sensor functionality.

Design and fabrication of a high-performance electrochemical glucose sensor.

Objective: Development of electrochemical sensors for continuous glucose monitoring is currently hindered by a variety of problems associated with low selectivity, low sensitivity, narrow linearities, delayed response times, hysteresis, biofouling, and tissue inflammation. We present an optimized sensor architecture based on layer stratification, which provides solutions that help address the aforementioned issues.

Method: The working electrode of the electrochemical glucose sensors is sequentially coated with five layers containing: (1) electropolymerized polyphenol (PPh), (2) glutaraldehyde-immobilized glucose oxidase (GOx) enzyme, (3) dip-coated polyurethane (PU), (4) glutaraldehyde-immobilized catalase enzyme, and (5) a physically cross linked polyvinyl alcohol (PVA) hydrogel membrane.

Edge-plane microwire electrodes for highly sensitive H₂O₂ and glucose detection.

The promise of implantable electrochemical sensors is often undermined by the critical requirement of device miniaturization that inadvertently degrades sensor performance in terms of sensitivity and selectivity. Herein, we report a novel miniaturized and flexible amperometric sensor grown at the 'edge plane' of a 25-μm gold wire. Such geometry affords extreme miniaturization along with ease of fabrication, minimal iR drop and 3-D diffusion for effective mass transfer.

Highly sensitive and reusable Pt-black microfluidic electrodes for long-term electrochemical sensing.

Highly sensitive, long-term stable and reusable microfluidics electrodes have been fabricated and evaluated using H2O2 and hydroquinone as model analytes. These electrodes composed of a 300 nm Pt-black layer situated on a 5 μm thick electrodeposited Au layer, provide effective protection against electrooxidation of an underlying chromium adhesion layer. Using repeated cyclic voltammetric (CV) sweeps in flowing buffer solution, highly sensitive Pt-black working electrodes were realized with five- (four-) decade linear dynamic range for H2O2 (hydroquinone) and low detection limit of 10 nM for H2O2 and 100 nM for hydroquinone.

Direct laser desorption/ionization time-of-flight mass spectrometry of conjugated polymers.

Two conjugated polymers (CPs), poly(9,9-dioctylfluorene) (PF) and poly(3-octylthiophene) (PT) were analyzed by direct laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF MS). Because of their strong absorption near the wavelength of the laser (337 nm), easy and transient energy transfer properties and sufficient thermal stability, CPs can be desorbed and ionized directly without a matrix. For comparison, these two polymers were also analyzed using matrix-assisted laser desorption/ionization (MALDI)-ToF MS in the positive reflectron mode.