Pulsed-Heating System With an Integrated Metal-Oxide Sensor Array Scheming Low-Power Temperature Modulation

Sensor integration and low-power operation are required to collect different molecular information. However, it is challenging to integrate different types of sensors onto a single chip. To obtain multiple molecular information, temperature modulation of metal-oxide gas sensors is highly effective since it allows for the variation of sensor molecular sensitivity based on the operating temperature. This paper covers a proposed novel system using metal-oxide gas sensors. The temperatures of the sensors are controlled by adopting self-heated sensors, which achieve local temperature increase and low-power operation. To simultaneously heat multiple sensors, we implemented a printed circuit board (PCB) for pulsed-heating scheme and streamlined intended input power with a proportional-integral-derivative (PID) controller. The performance of the implemented circuit is evaluated, maximum error rate of 1.7 % of heating accuracy and 0.68 % of average readout accuracy is ensured. As a proof-of-concept of the proposed gas sensory system, an array of 16 self-heated sensors was fabricated on a chip and tested with reactive gas molecules. The PID controller set the input power in 8 ms and kept constant power while sensor resistance changed. The proposed pulsed-heating measurement and conventional continuous-heating measurement were experimentally compared. The results of the experimental comparison suggest that while the sensitivity of the proposed pulsed-heating measurement decreases slightly, the power consumption due to heating can be reduced by up to 1/16.