A novel pressure sensing mechanism in a microchannel based on the surface tension and thermodynamic p-v-T relation

Abstract

A simple and cost-effective pressure sensing mechanism which can readily be used to increase measurement resolutions has been introduced. The proposed method measures the local static water pressure in a microchannel using the surface tension and thermodynamic p-v-T relation of air. The idea was tested using a microchannel along which a series of closed-end taps were perpendicularly placed. The prototype device was fabricated with SU-8, a negative photoresist. The dimension of the microchannel was 50 mu m x 7 mu m x 2.4 mm (W x H x L). The closed-end taps were located every 100 mu m along the microchannel with various dimensions of 5-20 mu m x 7 mu m x 500-1500 mu m (W x H x L). The surface tension was calculated through contact angle measurement on the water-air-SU-8 interface. Experiments were performed by imaging the meniscus location and were compared with analytical calculations. The proposed pressure sensing method showed good agreement with the analytical predictions and feasibilities as a valid pressure sensing mechanism in a microscale flow.