Development of reactive ion etching process for deep etching of silicon for micro-mixer device fabrication

In the present work, we report the design, fabrication, packaging and testing of a micro-mixer microfluidic device in 2" diameter silicon substrate. For this purpose, long and deep (~ 80 μm) channels in silicon were formed employing modified reactive ion etching (RIE) process. The RIE process parameters were carefully optimised for obtaining fast etch rate for creating 80 μm deep channels. Silicon wafers were anodically bonded to a Corning^® 7740 glass plate of identical sizes, for the purpose of fluid confinement. Through holes were made either in silicon substrate or in glass plate for formation of input/output ports. The channels were characterized using stylus and optical profilometers. The micromixer device was packaged in a polycarbonate housing and pressure drop versus flow rate measurements were carried out. The Reynolds Number and Friction Factor were calculated and it was concluded that the flow of gas was laminar at flow rates of oxygen ranging from 0.4 to 25 seem.