Performance Enhanced Thermal Flow Sensor with Novel Dual-Heater Structure Using CMOS Compatible Fabrication Process

For the first time, a CMOS compatible calorimetric flow sensor with a dual-heater (DH) structure is proposed instead of using the traditional single-heater (SH) design. CFD simulation results demonstrated that the DH design can enhance the performance of the device with high sensitivity. Thereof, the DH sensor was fabricated with four suspended bridges and tested under three configuration modes: parallel-heater (PH) mode, full-bridge (FB) mode, and half-bridge (HB) mode. Experimental results demonstrated that the PH mode can achieve a high sensitivity of 403.25 mV/(m/s)/W, which is over 4 times that of the HB mode (83.7mV/(m/s)/W). This DH flow sensor under its PH mode can also provide an ultra large measurement range (±40 m/s) and fast response time (1.8 ms @16.7 m/s). The good performance of this novel flow sensor demonstrated its potential applications in respiration monitoring in medical areas and airflow control in HVAC systems for smart buildings.