Electroactive properties of electrospun silk fibroin for energy harvesting applications
Silk fibroin (SF) is a sustainable material explored with success in the textile and biomedical industries. This protein has outstanding mechanical and electrical properties that could be used for advanced technological applications. In this work, silk fibroin fibrous membranes were processed by electrospinning, with conditions obtained through orthogonal experimental design. Due to their high-water affinity, the membranes were stabilized against aqueous environments by exposure to methanol (MeOH) in vapor phase. Individual SF fibres present an apparent piezoelectric constant (d33) of 38 ± 2 pm/V for the as-spun ones and 28 ± 3 pm/V for those submitted to MeOH in vapor phase, a piezoelectric voltage coefficient (g33) of 1.05 and 0.53 Vm.N−1, respectively, a mechano-sensibility of 0.15 V kPa−1, an energy storage capacity of 85 μJ, and an efficiency up to 21%. When the SF is submitted to MeOH in vapor phase, no effect was observed in the protein secondary structures. This work represents a new insight into the origin of the piezoelectric properties of SF and opens new opportunities for applications in microelectronics engineering for self-powered epidermal electronics, implantable medical devices, and personalized health care systems.