Micro Flow Sensor With High Sensitivity and Resolution Based on Thermal Feedback and Digitized Power Distribution

In this article, we propose a micro flow sensor with enhanced sensitivity, resolution, and low temperature drift, utilizing a new strategy of thermal feedback (TF) and digital power distribution (PD) across two microheaters. The optimization of the TF-based flow sensor and its temperature compensation capability were validated using computational fluid dynamics model. The flow sensor was then fabricated using a platinum-sensitive material through an in-house developed MEMS process. Two sensors with different distances (D_sh) between the microheater and microsensor were tested in a thermostatic chamber with nitrogen gas flow ranging from −9 to 9 m/s. Sensor 2, with a D_sh of 34 μm, achieved the highest sensitivity of 27.71%/(m/s), which is 2.6× higher than our prior work. Additionally, the TF-based flow sensor exhibited an inherent temperature drift of less than 4% F.S. over an ambient temperature range of 0 to 50 °C, even without compensation. Furthermore, our sensor system demonstrated superior long-term stability, with a zero offset of less than 0.04% F.S. within 10 min, indicating an intrinsic resolution better than 1.44 mm/s. Therefore, this new strategy that combines digitized signals with thermal feedback proves beneficial for designing highly robust and low-temperature drift flow sensors.