Flexible pressure sensor constructed by polyurethane composite conductive sponge

Abstract

As the main core component of wearable devices, flexible strain sensors have broad application prospects in health monitoring, motion monitoring, human-machine interface, rehabilitation, entertainment technology and other fields. In this paper, a rectangular sandwich resistive pressure sensor is constructed with porous conductive sponge, and its working mechanism is analyzed. The linearity of the sensor is improved and the stress range is increased by gel modification. Through experimental tests, it can withstand more than 80% compressive strain, and shows a sensitivity of 0.398 kPa ^−1 in the range of 6 ∼ 11 kPa; the maximum range is close to 40 kPa, and the minimum detection limit is 20 Pa; under constant loading/releasing speed, the response/recovery time is about 133/150 ms; it also shows good linearity and stability. With the help of a single sensor entity, Morse code can be sent, and some human activity signals can be measured, such as speech recognition, weighing measurement, limb movement; and 8 sensors create an interesting smart insole for gait recognition. The results show that piezoresistive sensors with porous composite materials have broad application prospects in motion monitoring and human-computer interaction.

Keywords

• wearable electronics
• strain sensor
• resistive type
• electronic skin