Flexible, air permeable and elastic self-powered sensors
for human
motion monitoring and assisted medical rehabilitation have recently
become a hot research topic. However, most current piezoelectric sensors
can not account for many characteristics. Addressing this challenge,
an all-textile piezoelectric sensor (ATPS) based on 3D structured
knitted fabric electrodes is reported. The ATPS consists of a piezoelectric
element polyvinylidene fluoride nanofiber membrane, flexible knitted
fabric electrodes, and an elastic self-adhesive bandage. Based on
the flexible and efficient knitting technology, the sensor has the
advantages of low cost, flexibility, simple structure, and convenient
large-area manufacturing. Experimental and finite element simulation
results show that the knitting pattern of fabric electrodes can enhance
the piezoelectric output of ATPS. The optimal ATPS has a high voltage
response sensitivity of up to 0.68 V/kPa. The proposed ATPS responds
to a wide range of input forces from 0.098 to 724 N in self-powered
mode, verifying its feasibility as a tactile sensor for human motion
detection and recognition (throat swallowing, wrist bending, elbow
bending, knee bending, walking slowly, running fast) and as a pressure
sensor (Morse code, digit recognition) and demonstrating its potential
for motion tracking, medical rehabilitation, and human–computer
interaction.