Elasticity may stretch too far, causing problems in wearable sensors. A group of researchers at Yokohama National University has proposed a solution to prevent overstretching while improving the sensing capability of electronic devices. This could lead to advanced prosthetics or disaster recovery robotics technologies. They published their findings in Scientific Reports on 7 month 29 day.

Paper authors from the Faculty of Engineering at Yokohama National University, Associate Professor Hiroki Ota said: "Stretchable physical sensors are crucial for advanced electrical systems, especially for the development of wearable devices and soft robots. " "However, current stretchable pressure sensors composed of elastic materials may undergo severe deformation during device deformation. "

Bending of the elbow or knee can push the sensor beyond its structural integrity, resulting in large errors in pressure motion measurement. This prevents the sensor from simultaneously measuring pressure and strain as independent variables.

To address this issue, the researchers proposed a monolithic array of pressure and strain sensors that can independently detect the force of motion and bending deformation simultaneously. They used two different materials (one soft and one hard) to protect the stretching capability of the sensors while still accurately measuring motion. They placed a hard silicone resin called PDMS along the electrodes on the array. At the center of each PDMS placement, they placed soft porous silicone resin, which senses pressure.

Ota said: "The PDMS around the pressure sensing element prevents large deformations of the element during the generated device tension."

The hard shell of PDMS contains a soft porous silicone pressure sensor, so it can measure pressure without exceeding reliable error margins. The enclosure also allows the sensor to identify and measure pressure and strain, which are independent contributors to motion.

Ota said: "Furthermore, the resistance of the column electrodes and row electrodes in the mapping array matrix is much lower than that of the pressure sensor." "This control of substrate and electrode resistance prevents the stretching deformation of the device from affecting pressure sensing."

The electrodes in the stretchable array can measure strain at a rate much lower than that required for pressure detection.

Ota said: "We can independently identify the pressure and strain sensing of the device."

Ota stated that the team plans to apply the new stretchable sensor method to physical keyboards that can be mounted on the body surface, which can bend with body strain and still detect fingertip pressure, as well as physical sensors on soft robots. They also hope to use the sensors to better understand human hand movements and haptics.

Ota said: "In the future, by molding this sensor into a glove-like form, it can be applied to devices that electronically analyze finger movements and hand haptics."

Other contributors include Ryosuke Matsuda, Satoru Mizuguchi, Fumika Nakamura, Takuma Endo, Yutaka Isoda, and Tsuyoshi Inamori, all affiliated with the Department of Mechanical Engineering at Yokohama National University.