Nano Flex Screen Protectors for 2D Material Piezotronics

We propose nano flex film, a commercially available mobile screen protector, as a prospective flexible substrate for piezotronic devices. Reliable fabrication methods on flexible substrates and robust testing methods are essential to explore piezotronic properties in emerging 2D materials. Unlike conventional rigid substrates, flexible substrates are challenging to handle during fabrication and subsequent testing. The fabrication process on the proposed flexible substrate is as seamless as on rigid substrates. The optimized methods to fabricate 2D material devices on nano flex films are presented. Inorganic dielectric materials such as silicon dioxide (SiO₂) offer good adhesion, better lifetime, and optical contrast to the 2D material flakes compared to polymer alternatives. The devices made on nano flex films with SiO₂ have shown almost three-fold improvement in open circuit voltage generated (50 mV) and strain gauge values (1997 at 0.44% strain). Also, a simple setup proposed for strain-dependent electrical measurements enables us to characterize the piezotronic properties of different 2D materials without wire bonding or probe needles.