Biomedical subjects

Peter R Fielden

Publications and source records attributed to Peter R Fielden.

22 records · Page 2Linked to original sources

PubMed2002

Rapid prototyping for injection moulded integrated microfluidic devices and diffractive element arrays.

This paper describes two fabrication procedures that makes it possible to design, fabricate and injection mold a microfluidic system with an on board coupling element or an optical array platform in less than four hours. Epoxy masters for the array and a single diffractive element were produced using conventional soft lithography techniques and a commercially available UV curable epoxy. The fabrication of the master for the integrated microfluidic device utilized the surface chemistry of polyester and its interaction with the anionic surfactant sodium dodecyl sulfate (SDS), to selectively inhibit the adhesion between the epoxy and the polyester film during the curing reaction. The transfer of a microfluidic design and the required coupling element (632 nm holographic grating) along the base of the channel was completed in a single step. The turnaround time from design to injection molded device whether a microchannel or array was 3.5 h.

Journal Article↗

PubMed2002

Asymmetric anti-resonant reflecting optical waveguides (arrow) as chemical sensors.

Anti-resonant reflecting optical waveguides (ARROW) are described which trap light in a low index layer between a lower, high-index confining layer and an upper total internal reflection boundary. In this configuration, most of the light (greater than 80%) travels in the low index porous polymer layer, the refractive index of which is monitored by examining the angle at which light is coupled out of the waveguide. It is shown that asymmetric ARROW sensors can be constructed using conventional chemical vapour deposition and spin-coating techniques and their sensitivity is as predicted by theoretical modelling.

Journal Article↗

PubMed2002

Internally-referenced resonant mirror for chemical and biochemical sensing.

The resonant mirror sensor is a planar optical sensor platform that uses frustrated total internal reflection to couple light into and out of a leaky waveguiding layer. The evanescent wave associated with the dielectric structure is very sensitive to changes in surface refractive index caused by the binding of macromolecules to immobilised proteins or other biorecognition species such as antibodies. However, such variations can also be generated by variations in the bulk analyte solution, via changes in the composition or temperature. In the device described here, an additional buried resonant mirror layer is incorporated into the sensor structure generating an internal reference resonant mirror. The efficacy of this internal reference system is demonstrated in both chemical and immunological systems--as a pH sensor monitoring the absorption of an encapsulated sulfonephthalein dye, and as a refractive index sensor measuring the adsorption of anti-protein A and binding of its corresponding antigen. In both cases the internally referenced resonant mirror provides a means by which errors due to fluctuations in light intensity, temperature and bulk composition may be accounted for.

Adsorption↗

PubMed2002

Bidirectional isotachophoresis on a planar chip with integrated conductivity detection.

The use of a miniaturised planar separation device with integrated conductivity detection for performing bidirectional isotachophoresis (ITP) is described. The chips were produced in poly(methyl methacrylate) (PMMA) using a milling procedure. To enable bidirectional ITP the devices were designed to inject samples into the centre of the section channel and incorporated two integrated on-column conductivity detectors, positioned at opposite ends of this channel. When used with a hydrodynamic sample transport system the devices were used for the analysis of a range of small ions: NH4+; Na+; Mg2+; Ca2+; Li+; NO3-; ClO4-; SO4(2-); F-. Results sucessfully achieved included the simultaneous separation of three anions and three cations.

Journal Article↗