Will Ultrasonic ToF Sensors Replace PIR & Microwave Sensors?

TDK Corporation has launched full-scale production of its InvenSense SmartSonic ICU-30201 ultrasonic time-of-flight (ToF) sensor, in January 2025. This sensor enhances contextual awareness for various applications requiring accurate presence, proximity, and distance measurements, including robotics, drones, alarm devices, door locks, camera devices, and other smart building systems such as lighting. Its enhanced maximum range, low power consumption, and on-chip processing power to detect minor human motions positions it to compete against PIR sensors, while maintaining a battery-friendly power budget.

The ICU-30201 offers room-scale presence sensing and long-range obstacle detection. Its extended maximum range enables a new class of devices in these sectors. As the latest addition to the SmartSonic sensor family, it features a more powerful on-chip processor with higher computational capabilities.

Key features of the ICU-30201 include:

1.  On-chip algorithms for range finding and presence-sensing, reducing system MCU load and power consumption.
2. Customizable algorithms, allowing customers to write their own for the sensor.
3. A new bottom port package design for easy mechanical integration.
4. Integration of a MEMS PMUT (Piezoelectric Micromachined Ultrasonic Transducer) with an ultra-low power SoC (system on chip).
5. Highly accurate and robust range measurements up to 9.5 meters (30 ft).
6. Functionality in any lighting condition, including full sunlight, independent of target color and optical transparency.
7. Ultra-compact package footprint of 5.17 x 2.68 x 0.9 mm³.

The sensor’s capabilities were showcased at CES 2025 in Las Vegas, where accessibility technology company WeWALK demonstrated InvenSense’s ultrasonic time-of-flight sensors at the TDK booth. WeWALK also announced their AI-powered Smart Cane 2, which incorporates TDK sensors, including the ultrasonic ToF, to enhance mobility for visually impaired individuals.

The ICU-30201 is now available from multiple distributors worldwide, offering product designers and engineers a new tool for creating intelligent and responsive devices in the smart home and building automation sectors. This sensor’s advanced capabilities and compact size make it a versatile solution for a wide range of applications, potentially improving how smart products interact with our environment and improving accessibility for those with visual impairments. But will the lighting industry opt for ultrasonic ToF sensors over the PIR or microwave sensors commonly used today for occupancy and motion sensing luminaires?

Advantages of Ultrasonic ToF Sensors

• Extended Range: The ICU-30201 can measure distances up to 9.5 meters, enabling room-scale presence sensing and long-range obstacle detection.
• Accuracy and Robustness: Ultrasonic ToF sensors provide highly accurate and robust range measurements in various lighting conditions, including full sunlight.
• On-chip Processing: The ICU-30201 features a powerful on-chip processor, allowing for advanced algorithms to run directly on the sensor, reducing system power consumption.
• Versatility: Ultrasonic sensors can detect a wide range of materials, including metal, plastic, wood, and liquid.
• Environmental Resilience: These sensors perform well in various environments, including dusty, foggy, or misty conditions, where optical sensors might struggle.

Comparison with PIR and Microwave Sensors

• Sensitivity: Ultrasonic sensors can detect minor motions and do not require a direct line of sight, unlike PIR sensors
• Power Consumption: Ultrasonic sensors generally consume more power than PIR sensors but less than microwave sensors.
• False Alarms: Ultrasonic sensors may have fewer false alarms compared to microwave sensors, which can be triggered by electromagnetic radiation
• Cost: PIR sensors are typically the most cost-effective option, followed by ultrasonic sensors, with microwave sensors being the most expensive.
• Application Suitability: PIR sensors are better for enclosed spaces and areas requiring strict coverage definition, while ultrasonic sensors excel in spaces with obstacles or requiring detection of minor movements

Future Outlook

While ultrasonic ToF sensors like the ICU-30201 offer significant advantages in certain applications, they are unlikely to completely replace PIR and microwave sensors for several reasons:

• Established Technologies: PIR and microwave sensors are well-established, with a large installed base and familiarity among installers and users.
• Cost Considerations: For applications where high precision is not critical, PIR sensors remain a cost-effective option.
• Specific Use Cases: Each technology has its strengths in particular applications. For example, PIR sensors are still preferred for battery-operated devices due to their low power consumption.
• Hybrid Solutions: The trend towards dual-technology sensors, combining multiple sensing methods, suggests that manufacturers see value in leveraging the strengths of different technologies rather than relying on a single type.

While ultrasonic ToF sensors like the ICU-30201 are likely to gain significant market share in smart home and building automation applications due to their advanced capabilities, they will likely coexist with PIR and microwave sensors rather than completely replacing them. The choice of sensor will continue to depend on specific application requirements, environmental conditions, and cost considerations.

More information on the TDK ToF sensor is available here.

Image: TDK

David Shiller

David Shiller is the Publisher of LightNOW, and President of Lighting Solution Development, a North American consulting firm providing business development services to advanced lighting manufacturers. The ALA awarded David the Pillar of the Industry Award. David has co-chaired ALA’s Engineering Committee since 2010. David established MaxLite’s OEM component sales into a multi-million dollar division. He invented GU24 lamps while leading ENERGY STAR lighting programs for the US EPA. David has been published in leading lighting publications, including LD+A, enLIGHTenment Magazine, LEDs Magazine, and more.

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