A Novel Pneumatically Driven SU-8 Microvalve for High Speed Gas Chromatographic Applications

A. Nubile, A. Poggi, E. Cozzani, I. Elmi, S. Zampolli, M. Messina, G.C. Cardinali, F. Mancarella, M. Belluce

Keywords: integrated fluidic microvalves, SU-8, high speed gas chromatography, MEMS


Microvalves are basic components of microfluidic systems and MEMS technology has provided an opportunity for microvalves to be packaged onto a board with integrated microfluidic channels. For the successful miniaturization of integrated fluidic devices, it is desirable to have a reliable non-leaking microvalve that can be used in various environments, in a wide temperature range and that is chemically inert. This work describes the design, fabrication and characterization of an innovative pneumatically driven microvalve based on an SU-8 actuating membrane, to be employed in high-speed gas chromatographic (HSGC) applications. In this scenario, a critical constrain is the volume of the microvalve, which needs to be as small as possible to reduce the response time of the chromatograph. The proposed microvalve consists of an SU-8 membrane layer deposited between two micromachined silicon wafers. On the upper wafer, DRIE is employed to obtain an actuation hole, extending all through the Si substrate, for enabling the deformation of the actuating membrane. In the lower wafer, the fluidic circuit is fabricated by DRIE processes and the bonding between the two silicon wafers is done using an additional SU-8 spacer layer. Experimental characterization of SU-8 microvalves indicates very good sealing properties under different working conditions.