Analytical modelling of thermopile based flow sensor and verification with experimental results

A novel, simple approach for analytical modelling of thermal flow sensors has been implemented. It is based on unification of results obtained using the already developed two-zone analytical model and theory of laminar fluid flow over uniformly heated plate. This model can be used in order to extract the main parameters for various geometrical configurations of thermal flow sensors. Presented analytical model was further verified by experimental results. Flow tests were performed using multipurpose MEMS flow sensors consisting of two thermopiles, with 30 p(+)Si/Al thermocouples each, and a "U" shaped p(+)Si heater. Thermally isolating membrane was formed of sputtered SiO(2) and residual n-Si layer. Experimental evaluation was performed under various flow conditions and applied heating power values. The results showed excellent agreement with theoretical predictions.