Graphene-Based Ultrasensitive Strain Sensors

In this work, a simple-structured and low-cost graphene woven fabrics(GWFs) strain sensor has been fabricated to readily distinguish various strain levels of human motion signals. When a stress is applied on the strain sensor, high-density cracks appear in the GWFs network and cause the decrease of the current pathway and the increase of the resistance. Such GWFs possesse an extremely high gauge factor, ~103 under 2~6% strains, 106 under higher strains(>7%), and 35 under tiny strain of 0.2% due to this special crisscross configuration. Such sensors can umbiguously detect the signals of any weak muscle motions, including breathing, expression changes, blink, and pulse. On the other hand, this sensor could endure a large deformation of 30% with the completely reversible electrical property. In additon, the device is wearable and has excellent biomedical compatiblility.A wearable and highly sensitive sensor has been also fabricated from thin film of special crisscross graphene woven structures for sound signal acquisition and recognition. This strain sensors placed on human throat are able to record one’s words through the muscle movement no matter the sounds are made or not. The realization of fast and low frequency sampling of speech by extracting the signature characteristics of sound waves has been achieved due to the ultra-high sensitivity of the sensor. The representative signals of 26 English letters, typical Chinese characters and tones, even phrases and sentences, are recognized by obvious characteristic resistance changes. This graphene sensor will be able to deal with complex acoustic systems and large quantities of audio data based on the combination of artificial intelligence with digital signal processing.