Micromolded Carbon Paste Microelectrodes for Electrogenerated Chemiluminescent Detection on Microfluidic Devices

Micromolded carbon paste electrodes are easily fabricated, disposable, and can be integrated into microfluidic devices to fabricate inexpensive sensors and biosensors. In this work, carbon paste microelectrodes were fabricated in poly(dimethylsiloxane) using micromolding techniques and were coupled to a microfluidic channel to fabricate electrogenerated chemiluminescence (ECL) sensors. ECL was generated using both the tris(2,2’-bipyridyl)ruthenium(II)/tripropylamine system and the hydrogen peroxide/luminol system. For each of these ECL systems, the sensor fabrication method was optimized, along with key experimental parameters (applied voltage, solution flow rate, buffer species and luminol concentration). The limit of detection (S/N=3) for TPrA was approximately 2.4 μM with a linear range of 10–100 μM. For hydrogen peroxide, the LOD was approximately 11 μM and the electrodes gave a linear response between 30 μM and 200 μM hydrogen peroxide. Electrodes containing glucose oxidase were fabricated using this new method, demonstrating that glucose could be indirectly detected via generation of hydrogen peroxide by the enzymatic reaction at the micromolded biosensor.