Design and Fabrication of Novel Compliant Electrostatically Actuated Microvalves
Electrostatically actuated microvalves are appealing candidates to build fully integrated microfluidic circuits because of the direct transduction of electrical signals into mechanical responses at low power consumption levels. Practical solutions, however, are still lacking due to their multi-layered architecture and difficulties in incorporating heterogeneous materials. In this paper, we report the design and fabrication process of an electrostatically actuated gas microvalve amenable to large scale integration for gas flow control. The device we designed consists of an upper die, containing a flexible electrode sealed by a thin elastic membrane, and a lower die, containing gas channels of trapezoidal cross-section and fixed electrodes. Each microvalve is defined by one fixed electrode spanning the floor and sidewalls of the trapezoidal gas channel and one corresponding flexible electrode suspended above the channel. In contrast to the conventional parallel-plate arrangement of electrodes, the two electrodes are approximated starting from the edges of the trapezoidal gas channel during the actuation step, which is advantageous for lowering the required actuation voltage. The upper die was fabricated by replica molding in polymeric material, the lower die was fabricated in a glass substrate by conventional microfabrication techniques, and the two dies were subsequently aligned and bonded using an adhesive layer. This reported low cost fabrication process could be implemented in any basic microfabrication facility. When a net pressure up to 1 bar was applied to the gas channel, reasonable flow rate was achieved. We also observed displacement of the flexible membrane when a DC voltage of 200 V was applied to a pair of electrodes. These preliminary results show that this microvalve is a promising candidate for integrated on-chip valving and will allow for building large scale microfluidic circuits with reduced power consumption.
Selin Teo, A. Q. Liu, H. Li and B. Tarik
Q. Zhang et al., "Design and Fabrication of Novel Compliant Electrostatically Actuated Microvalves", Advanced Materials Research, Vol. 74, pp. 179-182, 2009