Sekisui Develops Piezoelectric Sensor Using General-purpose Material

Apr 15, 2014
Mami Akasaka, Nikkei Technology Online
The basic function of the sensor (image courtesy of Sekisui Chemical)
The basic function of the sensor (image courtesy of Sekisui Chemical)
[Click to enlarge image]
The mechanism of the sensor
The mechanism of the sensor
[Click to enlarge image]

Sekisui Chemical Co Ltd developed a piezoelectric sensor by using a polyolefin foam with a foam structure designed by the company.

When a pressure is applied to the electrically-charged polyolefin foam, the sheet-like sensor transmits an electrical charge generated by the slight form change to an aluminum sheet and displays it as an electrical signal. Because the new sensor can detect slight pressures applied to body surface by, for example, heartbeat, pulse and respiration, it is expected to be employed in the fields of healthcare, etc.

While conventional piezoelectric sensors use special plastic sheets, the new sensor is made by using general-purpose polyolefin and, thus, can be provided to various fields, Sekisui Chemical said. Specifically, the company is considering applying the sensor to (1) a vehicle seat capable of recognizing a sleeping or fatigued driver, (2) bedclothes for monitoring the user's health condition for a long period of time, (3) mattress for monitoring an elderly person and (4) wearable devices.

Sekisui Chemical is now ready to ship samples. And it plans to exhibit the sensor at Automotive Engineering Exposition 2014, which will take place from May 21 to 23, 2014, in Yokohama, Japan.

The piezoelectric sensor is 700μm thick and can be produced in sizes ranging from 2 x 2cm to 100 x 100cm. It endures a temperature of 80°C and humidity of RH95% for three months and a temperature of -20°C for three months.

The sensor can be bent up to 500 times. Its maximum withstand pressure is 2MPa. It can detect pulse with a sensitivity of 30mV/N. It is possible to extract pulse, respiration, snoring and body motion data by circuit processing.