Development of Piezoelectric Silk Sensors Doped with Graphene for Biosensing by Near-Field Electrospinning

Abstract

A novel piezoelectric fiber sensor based on polyvinylidene fluoride piezoelectric (PVDF) doped with graphene is presented. The near-field electrospinning technology was used for developing the sensor. The uniform experimental design method was introduced to determine the ranges of experimental parameters, including the applied voltage, the drum speed range, the graphene doping ratios from 0% to 11 wt% in PVDF solution, and the electrode gap. By experimental results, the conductivities of PVDF solutions with different doping ratios of graphene increased from 19.6 μS/cm to 115.8 μS/cm. Tapping tests were performed to measure the voltages and currents produced by the piezoelectric fibers. The maximum output voltage was 4.56 V at 5 wt% graphene doping ratio in PVDF fibers, which was 11.54 times that of the pure PVDF sensors. Moreover, mechanical properties of the proposed sensor were measured. Motion intention and swallowing test, such as saliva-swallowing and eating, were carried out. When the subject spoke normally, the output voltage of the sensor was between 0.2 and 0.4 V, approximately. Furthermore, when the subject drank water and ate food, the output voltage of the sensor was between 0.5 and 1 V, approximately. The proposed sensor could be used to detect signals of the human body and serve as a wearable device, allowing for more diagnosis and medical treatment.

Recent Advances in Physical Sensors Based on Electrospinning Technology

“…Common piezoelectric materials include inorganic materials and organic materials. The inorganic materials mainly include zinc oxide (ZnO), barium titanate (BaTiO 3 ), and lead zirconate titanate (PZT), while the organic materials mainly include PVDF and its copolymers. − Inorganic piezoelectric materials have the disadvantages of high polarization temperature, high preparation cost, and poor flexibility, while organic piezoelectric polymer materials have excellent mechanical flexibility, superior piezoelectric performance, multitechnology compatibility, biocompatibility, and low cost. − …”