Development of Vacuum-Chamber-Type Capacitive Micro-Pressure Sensors

Area of Science:

• Sensor Technology
• Microelectromechanical Systems (MEMS)

Background:

• Accurate dynamic pressure measurement is crucial for understanding fluid dynamics.
• Existing sensors may lack the required sensitivity or linearity for low-pressure flow fields.

Purpose of the Study:

• To develop and characterize a high-resolution capacitive pressure sensor for dynamic flow field applications.
• To leverage CMOS-MEMS technology for integrated sensor fabrication.

Main Methods:

• Fabrication using UMC 0.18 μm CMOS-MEMS process with post-processing (metal etching, supercritical CO2 drying, parylene encapsulation).
• Utilized AD7746 capacitance-to-voltage converter (CVC) for signal processing.
• Designed a vacuum-sealed diaphragm capsule with dual movable circular membranes and a trapezoidal/Gong-like vacuum-chamber diaphragm for contact-mode capacitive sensing.

Main Results:

• The developed capacitive pressure sensor demonstrates feasibility for dynamic pressure measurement.
• Achieved an output sensitivity suitable for resolutions as low as 1-2 Pa.
• The design enhances linearity and sensitivity through its specific diaphragm and chamber configuration.

Conclusions:

• The CMOS-MEMS capacitive pressure sensor is a viable solution for precise dynamic pressure measurements in flow fields.
• The sensor design offers improved performance characteristics for low-pressure sensing applications.
• Further integration and application in fluid dynamics research are anticipated.