Design and Calibration of High-resolution Low-noise Micro Flow Sensors for Cold Gas Thrusters

Micro flow sensors are critical for the precise measurement and control of gas flow in cold gas thruster systems, directly influencing the overall performance of these systems in space applications. However, conventional micro flow sensors suffer from limitations such as low resolution, high noise, and slow response time, which restrict their effectiveness in high-precision scenarios like drag-free control for space-based gravitational wave detection. To address these challenges, this paper presents the development of a MEMS-based micro flow sensor system utilizing the constant temperature difference principle. The sensor incorporates four MEMS platinum resistors arranged in a constant temperature difference configuration. A high-precision constant temperature difference driving circuit maintains a stable temperature gradient at the sensor's detection site, ensuring enhanced measurement consistency. The sensor system employs a temperature measurement bridge, which converts minute temperature variations into electrical signals. These signals are subsequently amplified by a high-precision programmable amplifier and digitized using a 24-bit high-resolution ADC. This approach significantly reduces noise while improving measurement precision, overcoming the limitations of traditional micro flow sensors. Experimental results demonstrate that the developed micro flow sensor achieves an equivalent output noise of less than 0.126 μL·s^–1·Hz^–1/2 in the frequency range of 0.05 Hz to 1 Hz. Additionally, it offers an ultra-high resolution of better than 0.06 μL·s^–1, a measurement range of 0 to 1000 μL·s^–1, and a rapid response time of 1.2 ms. These improvements in measurement resolution, noise suppression, and response speed significantly enhance the sensor’s performance, making it well-suited for demanding aerospace applications. The advancements in this micro flow sensor system provide crucial technical support for cold gas thruster systems in space gravitational wave detection missions. By improving flow measurement accuracy and stability, this sensor contributes to the enhanced performance of drag-free control systems, ensuring the precise and stable operation of spacecraft during gravitational wave observations.