Glycine-Chitosan-Based Flexible Biodegradable Piezoelectric Pressure Sensor

摘要

This paper presents flexible pressure sensors based on free-standing and biodegradable glycine-chitosan piezoelectric films. Fabricated by the self-assembly of biological molecules of glycine within a water-based chitosan solution, the piezoelectric films consist of a stable spherulite structure of beta-glycine (size varying from a few millimeters to 1 cm) embedded in an amorphous chitosan polymer. The polymorphic phase of glycine crystals in chitosan, evaluated by X-ray diffraction, confirms formation of a pure ferroelectric phase of glycine (beta-phase). Our results show that a simple solvent-casting method can be used to prepare a biodegradable beta-glycine/chitosan-based piezoelectric film with sensitivity (similar to 2.82 +/- 0.2 mV kPa(-1)) comparable to those of nondegradable commercial piezoelectric materials. The measured capacitance of the beta-glycine/chitosan film is in the range from 0.26 to 0.12 nF at a frequency range from 100 Hz to 1 MHz, and its dielectric constant and loss factor are 7.7 and 0.18, respectively, in the high impedance range under ambient conditions. The results suggest that the glycine-chitosan composite is a promising new biobased piezoelectric material for biodegradable sensors for applications in wearable biomedical diagnostics.