Heater-Integrated Flexible Piezoresistive Pressure Sensor Array for Smart-Car Seats

With the growing popularity of autonomous vehicles, the need for real-time monitoring of occupant posture has led to the requirement for a pressure sensor array. Moreover, heated car seats not only offer drivers comfort but also prevent cramped postures, allowing pressure sensors to accurately measure drivers’ pressure distribution and enhance safety in autonomous driving. Herein, we propose a heater-integrated pressure sensor array designed specifically for seats in a commercially available GV80 car. The unique signal lines in our sensor enable the implementation of both sensing and heating functionalities within a single substrate, streamlining the fabrication process for the heater-integrated sensor. The sensor was characterized in terms of sensitivity, linearity, response time, repeatability, hysteresis, body temperature effect, and pressure interference among sensing elements. Our sensor exhibited a wide linearity region of 17.06 kPa with a maximum linearity error of 4.4% and a fast response time of less than 4 ms. It operated reliably with a maximum relative standard deviation (RSD) of 5.2% and a hysteresis error of 12.2%. The maximum resistance difference affected by the body temperature was as small as 8.5%, and the resistance changes of one sensing element were almost constant, regardless of the pressure applied to the other sensing element. Additionally, we studied the variations in sensor characteristics with respect to heater temperatures. Furthermore, we customized the embedded system and graphical user interface (GUI) to demonstrate sensor responses according to five different postures. Thus, our heater-integrated sensor shows promise as a potential device for emerging smart-car seats.