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OKI Develops Ultra-sensitive Human-detecting Sensor Technology Capable of Detecting Minute Movements, Including Human Breathing


TOKYO, -- OKI (TOKYO: 6703) recently developed a human-detecting sensor technology capable of distinguishing between large movements (for example, a person walking about a room) to minute movements like breathing. This technology can detect even the minute movements of otherwise motionless persons, making it suitable for use in various applications, including advance warnings of health problems. OKI is currently seeking to apply this technology to areas ranging from security to the monitoring of elderly or people requiring long-term care.

Detection when a person enters an empty room and sits in a chair: Identifies changes in behavior.

Use of pyroelectric infrared human-sensing sensors(*1) continues to grow for a wide range of applications involving the detection of humans in fields from security to monitoring and energy conservation. While this area of technology has been successfully applied to detect moving persons, it has been less successful in detecting people who are motionless. Focusing on microwave sensors(*2) that rely on the Doppler effect(*3) to penetrate and circumvent obstructions and allow detection and response to minute movements, such as breathing and heartbeats, OKI has pursued research on highly-sensitive methods for detecting human presence and behavior.

Previously used in certain human-detection applications, microwave sensors have suffered from certain shortcomings: when a single sensor is used to provide wide coverage over the typical room-sized space, in addition to actual motion inside the area being monitored, movements of air-conditioning equipment in the same area and movements of people or vehicles outside the space are also detected. These shortcomings made these sensors ill-suited to applications involving more than sensing localized large movements (e.g., automatic doors or gate monitoring installations).

OKI explored the differences in fluctuations caused by the movement of physical bodies, developing a statistical model to extract human movement with high precision while disregarding the effects of objects moving in the surroundings. Large volumes of test data were collected to simulate the environmental factors likely to be found in a typical home. In partnership with the Chuo University Statistical Data Analysis Group led by Professor Toshinari Kamakura, OKI analyzed this store of data to refine the model. The technology ultimately developed proved capable of detecting motionless humans based on minute movements, such as breathing, at levels of high precision unaffected by environmental factors.

“This technology can distinguish in real-time between resting and moving states. The detection results can also be aggregated to allow visualization of small changes in daily behavioral patterns,” says Takeshi Kamijoh, General Manager at OKI. “Future work will refine this technology to incorporate functions capable of detecting breathing and heartbeats or anomalous behavior. The associated data can be aggregated and analyzed over a cloud network to ensure early detection of problems, such as falling or health-related irregularities, and rapid response.”

The microwave sensors on which this technology is based do not require exposed sensor units, allowing the configuration of discreet, nonintrusive systems to reduce discomfort in privacy-sensitive locations. The sensors are capable of detecting motion through furniture or bedding and are unaffected by ambient temperature fluctuations or heat sources such as heaters, allowing use even in hot and humid locations like bathrooms. The technology is expected to be ideal for monitoring patients in homes or in hospitals.

OKI plans to apply such smart sensing technology(*4) to provide systems and solutions that contribute to a smart society. OKI will also seek to apply this technology to build a healthier society, one offering increased peace of mind, through demonstrations in smart communities and smart homes.

Some of the results of this study were presented at the 8th IEEE International Symposium on Instrumentation and Control Technology (ISICT2012) held in London on July 11. Part of this research was supported by “Adaptable and Seamless Technology Transfer Program through target-driven R&D”, Japan Science and Technology Agency.


*1 :Pyroelectric infrared human-detecting sensors

Sensors that use pyroelectricity to detect temperature fluctuations from infrared radiation emitted from humans and other targets. Inexpensive and widely used, these sensors cannot detect static objects free of temperature fluctuations. They are also susceptible to ambient temperature effects and impaired accuracy during summer months, when temperature differences between target surfaces and the surrounding environment are minimal.

*2 :Microwave sensors

Active sensors that use microwaves in the 10.5 GHz and 24 GHz frequency bands. These sensors are capable of detecting objects in surrounding areas by emitting radio waves and sensing the reflected waves. Sensors that leverage the Doppler effect are capable of detecting the speed of moving objects with high sensitivity.

*3 :Doppler effect

This is a phenomenon whereby the wave frequency of audio or electromagnetic waves varies depending on the difference in relative velocity between the wave source and the observer. The frequency varies in proportion to the difference in velocity. The phenomenon is also observed with waves that reflect off moving objects.

*4 :Smart sensing technology

The general term for an area of technology in which OKI is active; these technologies are capable of identifying real-world situations and attributes using advanced modeling technologies, analyzing sensor data acquired from image, radio, and acceleration sensors.

About OKI Electric Industry (OKI)

Founded in 1881, OKI Electric Industry is Japan’s leading telecommunications manufacturer. Headquartered in Tokyo, Japan, OKI provides top-quality products, technologies, and solutions to customers through its info-telecom systems and printer operations. Its various business divisions function synergistically to bring to market exciting new products and technologies that meet a wide range of customer needs in various sectors. Visit OKI’s global website at

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