A Low-Power Thermal-Based Sensor System for Low Air Flow Detection.

Area of Science:

• Sensor Technology
• Biomedical Engineering
• Microfluidics

Background:

• Accurate detection of low air flow rates is critical for automotive and biomedical applications.
• Existing sensors may lack the required sensitivity, accuracy, or power efficiency for certain biomedical uses.

Purpose of the Study:

• To develop a low-power, high-accuracy thermal-based air flow sensor system for biomedical applications.
• To design and simulate a novel sensor and its associated readout circuit.

Main Methods:

• A thermal-based air flow sensor was designed, comprising a heater and temperature sensors to detect temperature differences caused by laminar air flow.
• COMSOL MultiPhysics software was used for simulating laminar flow and heat transfer physics.
• A current-controlled ring oscillator circuit was designed using a 130-nm standard CMOS process for sensor readout.

Main Results:

• The simulated sensor demonstrated the capability to detect air flow rates as low as 0.0064 m/sec.
• The readout circuit exhibited low-power consumption (22.6 µW at 800 mV) and a small area.
• High linearity was observed between the ring oscillator's output frequency and temperature sensor resistance changes (R² = 0.9987).

Conclusions:

• The developed thermal air flow sensor and low-power readout circuit are highly suitable for biomedical applications.
• The system's low power dissipation, high linearity, and small dimensions meet key requirements for portable and implantable biomedical devices.