Single-Chip Integration of CMOS Compatible Mems Temperature/Humidity and Highly Sensitive Flow Sensors for Human Thermal Comfort Sensing Application

In this work, we report a single-chip integration of CMOS compatible MEMS temperature, humidity, and highly sensitive flow sensor for the application of human thermal comfort (HTC) sensing. The present multi-sensors chip (MSC) comes up with a couple of merits. Firstly, it utilizes a low-cost 3-mask fabrication process to fabricate temperature, humidity, and flow sensors on a single chip with a proper packaging layer (parylene C) that acts as both packaging (for temperature & flow sensors) and a humidity sensing layer. Secondly, a fully released thermoresistive calorimetric flow (TCF) sensor with dual pairs of detectors is fabricated to achieve high sensitivity. The fabricated (flow, humidity, and temperature) sensors were characterized under different air velocities, humidity, and temperature levels, respectively. The measurement results indicated a maximum sensitivity of 312 mV/ms−1 for the developed TCF sensor with dual detectors design which is almost doubled compared to conventional single pair of detectors design. Furthermore, the humidity sensor achieved an average sensitivity of 7.83 fF/%RH, whereas the temperature sensor shows a resistance change of $5.78\Omega/^{\circ}\mathrm{C}$ and TCR of $1.43 \times 10^{-3}/^{\circ} \mathrm{C}$ . The experimental results indicated that our MSC is promising for the HTC sensing application for smart buildings in the era of Internet of Things (IoT).