Poly‐<scp>l</scp>‐Lactic Acid/Graphene Electrospun Composite Nanofibers for Wearable Sensors
Xuan Li, Sai Chen, Xianye Zhang, Xianye Zhang, Jinhao Li, Haihui Liu, Na Han, Xingxiang Zhang, Xingxiang Zhang
Abstract
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.