How to Properly Use PMUT Sensors at Different Frequencies

As technology continues to advance, PMUT sensors (Piezoelectric Micromachined Ultrasonic Transducers) are revolutionizing ultrasonic applications with their advantages of miniaturization, low power consumption, and easy integration. However, the core performance parameter—operating frequency—directly determines detection range, resolution, and penetration capability. Precisely matching frequency to application scenarios is key to maximizing the value of PMUT sensors.

40kHz – Robust Penetration for Short-Range Sensing

Physical Advantages：

Low attenuation in common media (e.g., air)

Moderate wavelength (~8.8mm in air)

Typical Applications:

Smart cockpit CPD systems

Service robot navigation and obstacle avoidance

Smart toilet automatic sensing

Core Application Advantages:

Short-range detection/obstacle avoidance: Low attenuation enables reliable detection at distances of several meters in smart cockpits, service robots, drones, and smart home devices, balancing detection range and accuracy.

Gas/low-density medium detection: Higher coupling efficiency with low acoustic impedance media like air, suitable for flow meters and presence detection.

Cost and robustness: High technological maturity, easy to manufacture and integrate, and simpler system design.

65kHz – The Sweet Spot for Industrial Ranging and Environmental Sensing

Physical Advantages:

Balanced penetration power and accuracy in complex industrial environments

Wavelength ~5.2mm in air

Typical Applications:

Autonomous forklift pallet depth detection

Aerial work platform collision prevention

Cleaning robot/gate detection

Agricultural boom height monitoring

Core Application Advantages:

Strong anti-interference capability: Performs well in humid, dusty, or smoky environments without being affected by target material or color, outperforming optical sensors in avoiding false detections from stains, reflections, or low light.

Stable medium-range detection: Covers industrial short-to-medium distance high-accuracy requirements with real-time response (millisecond-level echo processing), ideal for dynamic mechanical control such as emergency stops.

Environmental adaptability: Withstands wide temperature fluctuations, supports concealed installation, and offers stronger dust and water resistance, ideal for outdoor heavy machinery.

450kHz – "Eagle Eye" for Precision Imaging and Non-Destructive Testing

Physical Advantages:

High frequency enables shorter wavelengths (~3.3mm in water)

Easier beam focusing

Typical Applications:

High-precision industrial non-destructive testing (e.g., electronic component packaging defects, composite material delamination)

Biomedical high-frequency ultrasonic micro-imaging (skin, ophthalmology, small animal research)

MEMS device structure and defect analysis

Core Application Advantages:

Sub-millimeter resolution: Capable of identifying sub-millimeter defects or subtle biological tissue changes (e.g., early lesions, micro-cracks in materials) with image detail far surpassing low-frequency sensors.

Micron-level thickness measurement and characterization: Measures thin layer or coating thickness with micron-level accuracy and analyzes internal microstructures (e.g., porosity, uniformity).

Surface and near-surface defect detection: Energy is concentrated near the surface, making it extremely sensitive to cracks, delamination, and other abnormalities.