Degumming effects of silk fabrics as piezoelectrics for nanogenerators

This study evaluated the suitability of silk fabric as a piezoelectric nanogenerator (PENG). A PENG with excellent mechanical and electrical properties as well as biocompatibility was fabricated using silk. Silk fibers are composed of sericin and fibroin, and effect of sericin on the piezoelectric properties was evaluated. X-ray diffraction, Raman spectroscopy, and Fourier transform infrared analyses showed that the presence of sericin reduced the piezoelectricity, and its removal (degumming) improved the electrical output characteristics of the specimens. The device output performance exhibited a positive dependence on pressure conditions, such as the load and pushing frequency. The generators prepared from specimens before and after degumming showed power densities of 0.43 and 1.52 mu W/cm2, respectively, at an applied stress of 110 N. The electrical properties of the fabricated silk PENG were stable even after 10,000 cycles. Silk-fabric PENGs can be fabricated as low-cost, high-output devices without additional processes, such as electrospinning or coating, and they show significant potential for application in biosensors, medical sensors, and implantable medical devices.