A novel flow sensor based on resonant sensing with two-stage microleverage mechanism

Area of Science:

• Micro-electro-mechanical systems (MEMS)
• Sensor technology
• Fluid dynamics

Background:

• Conventional flow sensors often lack high sensitivity and precision.
• Resonant sensing offers potential for improved flow detection.
• Microleverage mechanisms can amplify sensor response.

Purpose of the Study:

• To design, simulate, fabricate, and experimentally validate a novel resonant flow sensor.
• To implement a two-stage microleverage mechanism for enhanced sensitivity.
• To investigate the sensor's performance characteristics, including sensitivity and detection limit.

Main Methods:

• Utilizing two differential resonators for air flow rate transformation.
• Employing a two-stage microleverage mechanism for signal amplification.
• Ansys simulation for optimizing the microleverage mechanism and hair dimensions.
• Implementing a digital closed-loop driving technique with a phase frequency detector-based algorithm for resonance frequency detection and locking.
• Fabrication using a standard deep dry silicon on glass process.

Main Results:

• Achieved maximal mechanical sensitivity of approximately 7.41 Hz/(m/s)² at 22 kHz.
• Sensitivity increased 2.42 times with hair height extension from 3 mm to 9 mm.
• Confirmed a detection limit of 3.23 mm/s air flow amplitude at 60 Hz.
• Sensor dimensions: 5100 μm × 5100 μm × 100 μm, hair diameter 1000 μm.

Conclusions:

• The two-stage microleverage mechanism significantly enhances flow sensor sensitivity compared to single-stage designs.
• The developed resonant flow sensor demonstrates high performance and a low detection limit.
• The sensor shows considerable application potential in micro-autonomous systems, micro-air vehicles, and environmental monitoring.