Researchers make hand-drawn and flexible pressure sensors that can control a phone from underwater.
There is an increasing focus on flexible and wearable electronic devices that can sense and monitor heart rate, pulses, blood pressure and daily activities. But wearable devices can do much more than sensing and transmitting data.
Researchers from Soongsil University in Seoul have developed a wearable pressure sensor that can control a phone, to take photos and play music, even when the sensor is fully immersed in water. According to the researchers, this technology can transform the use of wearable electronics in healthcare, smart textiles and for specific applications including scuba diving equipment.
“Flexible electronics will usher in a whole new world of wearable technologies to monitor our health and lifestyles,” says Jooyong Kim, a materials scientist who led the research. “But until now, many of these applications have been held back because the pressure sensors they rely on could not handle being exposed to water. We have changed that.”
To demonstrate the applicability of their technology, researchers incorporated one of the sensors into a flexible face mask sensitive enough to detect the movement of air inside the mask. The sensor can track and report the rate of breathing of a wearer in real-time.
Like conventional flexible devices, the circuit was hand-drawn onto a conducting material with a marker-pen, which acted to shield the circuitry when the rest of the material was etched away. This is cheaper than traditional methods.
They then mounted a finger-print sized circuit on a blend of wet tissue paper and carbon nanotubes, which works to detect changes in pressure. They covered the sensors with a strip of tape to make it waterproof. Using machine learning technology to process the signals, the researchers found the sensors could feel and report applied pressures in the lab with up to 94% accuracy.
Moreover, the sensor, when connected to a Wi-Fi network, can control phone functions, including double touch, triple touch, short touch, and long touch patterns.
“We expect the readily-available materials, easy fabrication techniques, and machine learning algorithms we have demonstrated in this journal article will bring significant contributions to the development of hand-drawn sensors in the future,” says Kim.
The research appeared in the journal Science and Technology of Advanced Materials.