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AsianScientist (July 29, 2017) – Scientists in China and the US have invented a contact-dependent electronic sensor that allows users to control devices and type text using the blinking action of the eyes. They report their findings in Science Advances.

Human-machine interfaces (HMIs) involve communication between a person and an external device. Typically, HMIs rely on hand gestures or voice control, but these methods may be unsuitable for individuals suffering from disabilities or diseases that impair speech or major motor functions.

Existing non-invasive HMIs such as electroencephalograms (EEG), electromyograms (EMG) and electro-oculograms (EOG) make use of electrodes as sensors to detect and translate signals in the brain, muscle or eyes into physical commands. However, these methods have limitations, including low signal-to-noise ratios, long training periods before effective use, or comfort and aesthetic problems. Hence, there is a need to develop better sensors for HMIs that are more sensitive, precise, and acceptable to the user.

In recent years, triboelectric nanogenerators (TENGs) have been explored as alternative sensors to the traditional electrodes. These nanotechnology-based technologies produce electrical signals in response to a range of motions such as touching and sliding.

“Compared with previous bioelectrical-based HMI technologies such as EOG, TENG-based sensors are highly sensitive, producing signals hundreds of times that of EOG. They are stable, small, light, transparent, flexible, skin-friendly, low-cost, durable, and reusable,” said Professor Hu Chenguo of the Department of Applied Physics at Chongqing University and Professor Wang Zhong Lin of the School of Materials Science and Engineering at Georgia Institute of Technology.

In this study, the research team led by Hu and Wang created a TENG-based sensor to translate eye blinks into commands for external devices. They dubbed this the mechnosensational TENG (msTENG) which they mounted on the sides of eyeglasses to function as a wearable HMI.

The sensor makes direct contact with the wearer’s skin around the eyes and responds to changes in pressure when the wearer blinks. By recording changes in the voltage output of the msTENG when it was compressed by blinking action, the researchers observed changes in the voltage output of the sensor. By adjusting the threshold setting of the signals, different commands could be assigned to the type of blinking action performed.

“The output signal from the new msTENG can be 750 times than that from EOG, and as the signal from a voluntary fast blink is different from an involuntary light blink, we could use it to control devices such as house lamps and electric fans, and also perform text typing in a stable and reliable manner,” Hu told Asian Scientist Magazine.

The researchers also said that the msTENG technology can be regarded as a ‘third hand,’ which can be used to enable self-care for the disabled, ring a doorbell when one’s hands are occupied and communicate with intelligent robots.

“For our next step, we would like to assemble the msTENGs for use on different parts of the body to explore the great potential of TENG-based sensors in intelligent robotics,” the researchers said.

The article can be found at: Pu et al. (2017) Eye Motion Triggered Self-powered Mechnosensational Communication System Using Triboelectric Nanogenerator.
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Copyright: Asian Scientist Magazine; Photo: Chongqing University.
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