Development of low-cost planar electrodes and microfluidic channels for applications in capacitively coupled contactless conductivity detection (C D).

Electrochemical techniques are commonly applied to micro total analysis system (μTAS) devices mainly due to its high sensitivity and miniaturization capacity. Among many electrochemical techniques, capacitively coupled contactless conductivity detection (C D) stands out for not requiring direct electrode-solution contact, avoiding several problems such as electrolysis, bubble formation, and metal degradation. Furthermore, the instrumentation required for C D measurements is compact, low cost, and easy to use, allowing in situ measurements to be performed even by nonspecialized personal.

Monitoring cellulose oxidation for protein immobilization in paper-based low-cost biosensors.

The oxidation of paper by periodate was investigated and systematically characterized by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy, X-ray diffraction, goniometry, and dynamic mechanical analysis. For the first time, in situ FTIR microscopy analysis was performed, yielding chemical images of carbonyl groups on the cellulose fibers. The enhancement of protein immobilization on oxidized paper was quantified by a colorimetric assay with Ponceau dye, demonstrating that 0.

Fabrication of glass microchannels by xurography for electrophoresis applications.

This communication describes a simple and cost-effective method for fabricating glass microchannels by wet chemical etching using masks made by xurography in vinyl adhesive films. Analytical performance of microfluidic devices fabricated using the new approach was evaluated by microchip electrophoresis coupled to capacitively coupled contactless conductivity detection (C(4)D) and laser-induced fluorescence (LIF) detection.

Glass/PDMS hybrid microfluidic device integrating vertically aligned SWCNTs to ultrasensitive electrochemical determinations.

This communication reports a promising platform for rapid, simple, direct, and ultrasensitive determination of serotonin. The method is related to integration of vertically aligned single-walled carbon nanotubes (SWCNTs) in electrochemical microfluidic devices. The required microfabrication protocol is simple and fast.

Doping of a dielectric layer as a new alternative for increasing sensitivity of the contactless conductivity detection in microchips.

This communication describes a new procedure to increase the sensitivity of C(4)D in PDMS/glass microchips. The method consists in doping the insulating layer (PDMS) over the electrodes with nanoparticles of TiO(2), increasing thus its dielectric constant. The experimental protocol is simple, inexpensive, and fast.

A rapid and reliable bonding process for microchip electrophoresis fabricated in glass substrates.

In this report, we describe a rapid and reliable process to bond channels fabricated in glass substrates. Glass channels were fabricated by photolithography and wet chemical etching. The resulting channels were bonded against another glass plate containing a 50-microm thick PDMS layer.