Fibroin Silk Synthesis and Fabrication of Silk Fibroin/Graphene Oxide Nano-Sheet Film for Humidity Sensing

Silk fibroin (SF) is a natural material that has received special attention due to its excellent mechanical and electrical properties. Nowadays, it is tried to improve the properties of SF by adding other nanomaterials such as graphene oxide (GO). Here, we extracted SF from silk cocoon and studied its properties in pure state and in the combination with graphene oxide (SF/GO). The results have shown that the presence of graphene oxide in the structure of fibroin increases the random winding formation of SF. The measurements show that the water content has a great effect on the properties of SF and SF/GO films.  The contact angle (less than 70) indicates the hydrophilic property of these films. In addition, in times greater than 50 seconds, the contact angles drop to 27° and 5° for SF and SF/GO respectively. Also, the surface resistance of the completely dried SF/GO film increases from 50 kW/sq to 220 kW/sq for 42% wt water content.