study and evaluation of a pcb-mems liquid microflow sensor研究和评估pcb-mems液体微流传感器.pdf

Sensors 2010, 10, 8981-9001; doi:10.3390/s101008981 OPEN ACCESS sensors ISSN 1424-8220 /journal/sensors Article Study and Evaluation of a PCB-MEMS Liquid Microflow Sensor Anastasios Petropoulos 1 and Grigoris Kaltsas 1,2,* 1 Institute of Microelectronics, NCSR-―Demokritos‖, P.O. Box 60228, 15310, Aghia Paraskevi, Athens, Greece; E-Mail: greenewal@ 2 Department of Electronics, Technological and Educational Institute of Athens, 12210, Aegaleo, Athens, Greece * Author to whom correspondence should be addressed; E-Mail: G.Kaltsas@ee.teiath.gr; Tel.: +30-2105385305; Fax: +30-2105385304. Received: 26 July 2010; in revised form: 1 September 2010 / Accepted: 1 September 2010 / Published: 8 October 2010 Abstract: This paper presents the evaluation of a miniature liquid microflow sensor, directly integrated on a PCB. The sensor operation is based on the convective heat transfer principle. The heating and sensing elements are thin Pt resistors which are in direct electrical contact with the external copper tracks of the printed circuit board. Due to the low thermal conductivity of the substrate material, a high degree of thermal isolation is obtained which improves the operating characteristics of the device. The sensor is able to operate under both the hot-wire and the calorimetric principle. In order to fully exploit the temperature distribution in the flowing liquid, multiple sensing elements are positioned in various distances