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

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 similar 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 (approximate to 66%), high output voltage (approximate to 21.3 V) and current (approximate to 0.68 mu A) with instantaneous power density of approximate to 4.56 mu W/cm(2). 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.