Polymer micro valve with a hydraulic piezo-drive fabricated by the AMANDA process

A normally-closed piezo-driven micro valve for gases and liquids has been developed. Due to the small deflection of piezo-actuated bending disks made of PZT a hydraulic transmission was constructed, which increases the displacement of the piezo disk up to the 25-fold. The switching times of the valve are shorter than 1.8 ms. Silicone gel serves as a transition medium in the hydraulic. It simplifies the manufacturing process and allows a flexible adaptation to different pressure requirements up to a differential pressure of 150 kPa switched with 300 V. Additionally, this silicone gel supports the sealing of the valve so it achieves an open-to-close ratio of 1: 150,000 or higher. The overall dimensions of the valve are 13 mm x 13 mm x 3 mm, the dead volume is 0.33 muA, and the inner diameter of the valve seat is 200 mum. A transformer as small as the micro valve is able to produce driving voltages of up to 300 V with a response time of 2 ms. Therefore, the valve could be integrated into hand-held systems which are battery powered with 5-15 V. (C) 2003 Elsevier B.V. All rights reserved.