Parts per trillion detection of heavy metals in as-is tap water using carbon nanotube microelectrodes.

Heavy metal contamination of drinking water is a major global issue. Research reports across the globe show contamination of heavy metals higher than the set standards of the World Health Organization (WHO) and US Environmental Protection Agency (EPA). To our knowledge, no electrochemical sensor for heavy metals with parts per trillion (PPT) limits of detection (LOD) in as-is tap water has been reported or developed.

The effect of the physicochemical properties of bioactive electroconductive hydrogels on the growth and proliferation of attachment dependent cells.

The physicochemical properties of soft electrode materials for the abio-bio interface of advanced biosensors and next generation bionic devices in the form of electroconductive hydrogels (ECH) of interpenetrating networks of polypyrrole formed within poly(hydroxyethylmethacrylate)-based hydrogels were examined. The 1.5 mol% UV-crosslinked tetraethyleneglycol diacrylate (TEGDA) (step 1) poly(HEMA) and the electropolymerized (step 2) polypyrrole co-networks were covalently joined by the inclusion of a bifunctional monomer (1.

On-demand controlled release of anti-inflammatory and analgesic drugs from conducting polymer films to aid in wound healing.

An electronically-controlled drug delivery system (eDDS) for the on-demand release of anti-inflammatory, anti-microbial and analgesic agents to aid in wound healing is currently under development. The loading of several drugs into conductive polymer films and their subsequent on-demand, controlled release upon application of an electrical potential to the polymer film has been demonstrated. The loading and release (active and passive) of Ibuprofen sodium salt - a negatively charged analgesic and anti-inflammatory agent - from polypyrrole films is described.

Hydrodynamic focusing--a versatile tool.

The control of hydrodynamic focusing in a microchannel has inspired new approaches for microfluidic mixing, separations, sensors, cell analysis, and microfabrication. Achieving a flat interface between the focusing and focused fluids is dependent on Reynolds number and device geometry, and many hydrodynamic focusing systems can benefit from this understanding. For applications where a specific cross-sectional shape is desired for the focused flow, advection generated by grooved structures in the channel walls can be used to define the shape of the focused flow.

A metabolic biofuel cell: conversion of human leukocyte metabolic activity to electrical currents.

An investigation of the electrochemical activity of human white blood cells (WBC) for biofuel cell (BFC) applications is described. WBCs isolated from whole human blood were suspended in PBS and introduced into the anode compartment of a proton exchange membrane (PEM) fuel cell. The cathode compartment contained a 50 mM potassium ferricyanide solution.

Hydrodynamic and electrical considerations in the design of a four-electrode impedance-based microfluidic device.

A four-electrode impedance-based microfluidic device has been designed with tunable sensitivity for future applications to the detection of pathogens and functionalized microparticles specifically bound to molecular recognition molecules on the surface of a microfluidic channel. In order to achieve tunable sensitivity, hydrodynamic focusing was employed to confine the electric current by simultaneous introduction of two fluids (high- and low-conductivity solutions) into a microchannel at variable flow-rate ratios. By increasing the volumetric flow rate of the low-conductivity solution (sheath fluid) relative to the high-conductivity solution (sample fluid), increased focusing of the high-conductivity solution over four coplanar electrodes was achieved, thereby confining the current during impedance interrogation.

Characterization of electroconductive blends of poly(HEMA-co-PEGMA-co-HMMA-co-SPMA) and poly(Py-co-PyBA).

Electroconductive hydrogels (ECH) prepared as blends of UV-cross-linked poly(hydroxyethylmethacrylate) [p(HEMA)]-based hydrogels and electropolymerized polypyrrole (PPy) were synthesized as coatings on microlithographically fabricated interdigitated microsensor electrodes (IMEs) and microdisc electrode arrays (MDEAs). Hydrogels were synthesized from tetraethyleneglycol diacrylate (TEGDA), hydroxyethylmethacrylate (HEMA), polyethyleneglycol monomethacrylate (PEGMA), N-[tris(hydroxymethyl)methyl]-acrylamide (HMMA), and 3-sulfopropyl methacrylate potassium salt (SPMA) to produce p(HEMA-co-PEGMA-co-HMMA-co-SPMA) hydrogels. The conductive polymer was synthesized from pyrrole and 4-(3'-pyrrolyl)butyric acid by electropolymerization within the electrode-supported hydrogel.

Biomimetic hydrogels for biosensor implant biocompatibility: electrochemical characterization using micro-disc electrode arrays (MDEAs).

Our interest is in the development of engineered microdevices for continuous remote monitoring of intramuscular lactate, glucose, pH and temperature during post-traumatic hemorrhaging. Two important design considerations in the development of such devices for in vivo diagnostics are discussed; the utility of micro-disc electrode arrays (MDEAs) for electrochemical biosensing and the application of biomimetic, bioactive poly(HEMA)-based hydrogel composites for implant biocompatibility. A poly(HEMA)-based hydrogel membrane containing polyethylene glycol (PEG) was UV cross-linked with tetraethyleneglycol diacrylate following application to MDEAs (50 mum discs) and to 250 mum diameter gold electrodes within 8-well culture ware.

Towards an implantable biochip for glucose and lactate monitoring using microdisc electrode arrays (MDEAs).

A complete electrochemical cell-on-a-chip that uses the MicroDisc Electrode Array (MDEA) working electrode (WE) design was evaluated for eventual intramuscular implantation for the continuous amperometric monitoring of glucose and lactate in an animal trauma model. The microfabricated ECC MDEA5037 comprises two discrete electrochemical cells-on-a-chip (ECCs), each with a reference, counter, and MDEA working electrode. Each MDEA comprises 37 microdiscs (diameter = 50 microm) arranged in a Hexagonal Closed Packed (HCP) arrangement with a center to center distance (d) of 100 microm.

A 128-electrode three dimensional electrical impedance tomography system.

Electrical impedance tomography (EIT) is a new functional imaging technique. This paper presents the development of a new electrical impedance tomography system with 128 electrodes for impedance change detection and 3D imaging of the human thorax. The system consists of several modules, including multi-frequency current source, driving, measuring, data acquisition, and controlling and signal processing modules.

Application of the directed transfer function method to the study of the propagation of epilepsy neural information.

A study of the propagation of electroencephalogram (EEG) activity before seizure by means of the Directed Transfer Function (DTF) is presented. The DTF method is a multi-channel parametric method of analysis based on an autoregressive model, and is capable of supplying such information as the direction, spectra and dynamics of the propagation of EEG signals. This method is typically utilized to determine patterns of neural information flow.

Synthesizing multi-view video frames for coding patient monitoring video.

This paper presents a method to synthesize multi-view video frames to facilitate coding and transmission of patient monitoring video. The synthesis is carried out in the DCT domain by means of interlacing. The synthesized video provides a higher video coding efficiency, better synchronization of the video streams from multiple cameras, as well as the improved data loss resilience and protection of the video content.

Serotonin (5-HT) released by activated white blood cells in a biological fuel cell provide a potential energy source for electricity generation.

Previous studies by our group have demonstrated the ability of white blood cells to generate small electrical currents, on the order of 1-3 microA/cm(2), when placed at the anode compartment of a proton exchange membrane (PEM) biological fuel cell. In this research study, an electrochemical technique is used to further investigate the electron transfer ability of activated white blood cells at interfacing electrodes in an attempt to elucidate the mechanism of electron transfer in the original biological fuel cell experiments. Cyclic voltammograms were obtained for human white blood cells using a three-electrode system.

Biofuel cells: a possible power source for implantable electronic devices.

Biofuel cells were designed to investigate electricity production from Escherichia coli and human white blood cells as a preliminary investigation into the possible future use of such fuel cells as power sources for implantable electronic devices. The biofuel cell's function is based on the coupling of glucose oxidation to the reduction of oxygen to water. It might, therefore, be possible to utilize the cellular processes involved in oxidative metabolism to generate electrical energy for numerous medical applications.

Platform technologies to support brain-computer interfaces.

There is a lack of adequate and cost-effective treatment options for many neurodegenerative diseases. The number of affected patients is in the millions, and this number will only increase as the population ages. The developing areas of neuromimetics and stimulative implants provide hope for treatment, as evidenced by the currently available, but limited, implants.