A new MEMS-based vacuum sensor developed by researchers at the Aerospace Information Research Institute of the Chinese Academy of Sciences promises to redefine pressure monitoring in critical environments. Utilizing a dual-mode weak-coupling resonator (WCR), the sensor adapts between high-sensitivity and stable-accuracy modes, achieving reliable measurements from 0.3 to 100,000 Pa.

This innovation addresses long-standing limitations of conventional sensors. While Pirani gauges offer range, they lack accuracy and gas-independence. Capacitance diaphragm gauges (CDGs) provide precision but only within narrow spans. Hybrid systems tend to be bulky, and mode-localized sensors often sacrifice consistency across ranges. The new device overcomes these hurdles by uniting mode-localization with traditional resonance on a single compact chip.

Published May 21, 2025 in Microsystems and Nanoengineering, the study describes how the sensor automatically shifts between modes depending on pressure. Below 1,000 Pa, it uses mode-localized detection-sensing stiffness shifts via amplitude ratio changes with a sensitivity of 30,000 ppm/Pa and resolution of 0.1 Pa. Above this threshold, it switches to traditional resonance mode, measuring output frequency with 2 Pa resolution and high linearity.

At the heart of the sensor is a MEMS-fabricated two-degree-of-freedom WCR built on a deformable diaphragm and two H-type double-ended tuning fork resonators. This differential design minimizes noise and stress while maintaining compactness. Encased in a vacuum-sealed cavity, the entire chip occupies just 27.2 mm-far smaller than commercial counterparts. Tests across temperatures from -20 oC to 120 oC confirmed excellent stability, minimal drift, and low hysteresis.

"By combining two sensing principles within a single MEMS platform, we've created a device that's compact, precise, and scalable," said lead author Prof. Junbo Wang. "This dual-mode operation gives it a level of versatility that current vacuum sensors simply can't match."

The device's broad-range capability and independence from gas type reduce calibration demands, allowing seamless integration into semiconductor manufacturing, space probes, and other high-demand applications. Its performance and scalability suggest it could become a standard for real-time vacuum sensing in next-generation technologies.

Research Report:A novel high-performance wide-range vacuum sensor based on a weak-coupling resonator