Poly‐ l ‐Lactic Acid/Graphene Electrospun Composite Nanofibers for Wearable Sensors

Piezoelectric organic films as flexible and wearable pressure sensors are ideal materials for manufacturing of electronic skin. Poly‐ l ‐lactic acid (PLLA)/graphene composite nanofibers are fabricated by electrospinning. The relative crystallinity of the PLLA/graphene electrospun composite nanofibers increases from 9% to 30%. The d 14 value of sample K0.1 ( d 14 = 9.02 pC N −1 ) increases by 2048% compared with sample K0 ( d 14 = 0.42 pC N −1 ). Piezoelectric bioelectronic skin is fabricated using the PLLA/graphene electrospun nanofiber mat, polyester fabric, and poly(dimethylsiloxane) (PDMS). The maximum open‐circuit voltage ( V oc ) and short‐circuit current ( I sc ) of the wearable sensors are 184.6 V and 10.8 μA. The response generated by touching the bioelectronic skin can be converted to a digital signal. The piezoelectric bioelectronic skin is used to monitor the pulse of the human body. Based on the results, a pulse of 76 beats min −1 is calculated, which coincides with the normal human heart rate interval (60–100 beats min −1 ). The addition of graphene influences the fiber diameters, thermal stability, relative crystallinity, and the piezoelectric properties along the fiber axial direction ( d 14 ) of PLLA. This small, flexible sensor, which can achieve high sensitivity, can be used for physiological and health care monitoring phonetic recognition.