WSURF Case 924
Platinum Microelectrodes for Lab-on-a-Chip Devices
Miniaturized electrodes are one of the most important components of “lab-on-a-chip” devices for separation, pumping, sensing, and other bio-analyses. In microfluidic based chemical and bio-analytical operations, platinum electrodes are preferred to minimize the interaction with chemicals or biomolecules due to their chemical inertness. Though microfabrication techniques for patterning integrated platinum microelectrodes on silicon, quartz or glass substrates are available, no techniques have been reported so far for depositing platinum electrodes in soft polymeric microchannels.
A novel fabrication scheme has been developed by WSU researchers for forming integrated microelectrodes in a poly-di-methyl-siloxane (PDMS) microchip. This electrode fabrication technique consists of photolithography, thermal processing, sequential sputtering of titanium and platinum, and stripping off photoresist, while soft-lithography is used to form the microfluidic channels on PDMS.
This approach facilitates precise positioning of the electrodes with a micron-sized gap between them, and it can be used for both low and high aspect ratio channels. Platinum electrodes, formed on the PDMS channel surface, demonstrate very good interfacial adhesion with the substrate due to the use of a very thin titanium layer between the platinum and PDMS. The sputtered electrodes have a surface roughness of 50 nm and are able to sense picoA level current through benzene.
Advantages
- Lower cost of manufacture – mass production is possible
- Environmentally safe – does not require the use of nitric or hydrochloric acids typically used for non-PDMS microchannel surfaces.
IP Status
This technology is patent-pending and available for licensing.
