The function of microfluidic devices are greatly enhanced by plasma. Microchannels on clinical diagnostic devices are made “wettable” to bio-fluids without having an effect on the properties of the analyte itself.
Microfluidic devices require hydrophilic surfaces so that the analyte flows smoothly and consistently through the microchannels to the detection and processing elements on these devices. This flow is accomplished by a variety of pumping methods; electro-osmotic, thermal, mechanical, etc. Microfluidic device platforms are usually made from polymer materials (polystyrene, polydimethylsiloxane (PDMS)) that are inherently hydrophobic. One of the major problems caused by the hydrophobic nature of these materials is bubble trapping in the microchannels that inhibit fluid flow. Even when the channels are primed with alcohol and buffer solution, air bubbles can still pose a problem. Gas plasma treatment oxidizes the surface of the microchannels, making them hydrophilic and preventing the formation of air bubbles. Flow rates are also affected by surface charge densities during electrokinetic pumping. Plasma has been shown to effectively charge surfaces supporting the electro-osmotic flow. This is another benefit of plasma treating microfluidic devices.
