Characterization of a microfabricated device for chemistry on a chip
Abstract
Microfabricated devices are being investigated to perform a multitude of tests including biochemical assays, process monitoring, off-site testing, and near patient diagnostics. This work focused on the use of quartz microchips with microfluidic channels to perform chemical analyses. In open channel devices, the primary method for mixing is diffusion. In an EOF driven chip with a potential of 40 v/cm and a linear velocity of 20 μm/sec, 7.25 minutes were required for three inlet streams to completely mix in a 100 μm x 10 μm channel. Yet when using this device as a sensor in a slowly changing environment, a large working range was demonstrated for hydrogen peroxide (to 10−11 M) using chemiluminescent detection. To demonstrate extended applications on a chip, coupled enzyme assays were performed. Solutions of glucose oxidase (pH 7) and luminol/HRP (pH 13) were mixed in open channels, and an assay for glucose was demonstrated to 10−7 M. An assay for starch, coupled with the glucose assay, provided a working range to 10−4 M. A novel approach to drive reagents together on a chip was shown by using gravity (hydraulic pressure). Flow rates as low as 1.9 pL/sec (60 μL/yr) were possible using a 10 cm reagent height. An assay for hydrogen peroxide using the gravity device provided equivalent results as shown for the EOF driven sensor (10−11 M). Enzyme plugs were assayed to investigate the flexibility of the microchip as a amplification system to monitor low amounts of samples. A 13 amol horseradish peroxidase sample was detected using a chemiluminescent reaction, as was a 3 fmol glucose oxidase sample.
Degree
Ph.D.
Advisors
Regnier, Purdue University.
Subject Area
Analytical chemistry
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