A Nonlinear One-Dimensional Model of Thermoresistive Micro Calorimetric Flow Sensor for Response Time Improving

We developed a nonlinear one-dimensional (1-D) model to optimize the response time of the Thermoresistive Micro Calorimetric Flow (TMCF) sensor. The proposed sensor model was verified by the reported experimental data and it was further used for the efficient optimization of the TMCF sensor design with different key parameters: (1) the response time tau(c) prediction, (2) the optimum distance I) from microheater to thermal sensing element, (3) membrane thickness t (4) the depth of bottom cavity h. After that, we designed and fabricated a TMCF sensor with CMOS compatible materials using MEMS technology. The measured response time of the TMCF sensors with the nitrogen flow from 0 m/s to 8 m/s was in reasonable agreement with the theoretical prediction. Therefore, this nonlinear model can be quite useful for the design and optimization of a new TMCF sensor. Moreover, the measured response time of the fabricated flow sensor (pair 1) is as good as less than 6 ms, which reveals that our developed TMCF sensor can be used for the monitoring of human respiration in the future.