Fabrication of pneumatic valves with spherical dome-shape fluid chambers

Abstract

This paper describes a simple fabrication method for pneumatic valves with spherical dome-shape fluidic chambers and channels. The proposed method is based on replicating a deformed polydimethylsiloxane (PDMS) diaphragm using a variable PDMS mold during the liquid PDMS curing process. A PDMS mold structure with a sealed cavity is prepared through a typical replica molding process and structural bonding with a glass substrate. The PDMS diaphragm inflates due to thermal expansion of air in the sealed cavity when it is placed on a hotplate during the thermal curing process, and this shape is transferred to liquid PDMS poured on the active PDMS structure. The proposed pneumatic valve can then be fabricated by bonding the valve chamber to the diaphragm. The effectiveness of the proposed valve was verified through optical observations of the valve pattern and measurements of the temporal response of the flow rate using pressurized liquid flow rectified by the fabricated valve. A finite element method was used to provide a structural analysis of the valve diaphragm to examine the characteristics of the rectified flow rate of the working fluid due to structural deformation of the valve diaphragm. The proposed fabricated valve effectively overcame the drawbacks of micro-fluid channels with rectangular cross sections and was also suitable for other micro-devices with spherical dome-shape cross sections.