Nature driven spider silk as high energy conversion efficient bio-piezoelectric nanogenerator

Abstract

Spider silk fibers having remarkable protein sequence structure contain nature's most outstanding mechanical properties and unrivalled elasticity along with biocompatibility and biodegradability. Unfortunately, it remains completely unidentified how the mechanical properties of spider silk effectively contribute to the performance and integrity on piezoelectric nanogenerator. Here, using piezoresponse force microscopy (PFM), we report for the first time structure-dependent piezoelectric response of the spider silk at the molecular level and confirm that silk fiber shows vertical (or out of the plane) piezoelectric coefficient of up to ~ 0.36 pm/V. We also design a mechanically robust piezoelectric nanogenerator (PNG) using nature driven spider silk that exhibits high energy conversion efficiency (≈ 66%), high output voltage (≈ 21.3 V) and current (≈ 0.68 μA) with instantaneous power density of ≈ 4.56 μW/cm2. The fabricated device is biocompatible and ultra-sensitive towards physiological signal monitoring such as arterial pulse response which can be useful for potential biomedical applications.