Rewritable Optical Storage Medium of Silk Proteins Using Tip-Based Nanolithography

Breaking the optical diffraction limit is a prerequisite for the manufacturing and functioning of nanophotonics devices working with long-wavelength light. The near-field evanescent wave can serve as one powerful mean to induce locally confined high-field optical phenomena, enabling fabrication, manipulation, and characterization of photo-sensitive structures at the nanoscale. Here, we report a rewritable optical storage medium made of silk proteins (termed "silk-drive") using a home-built tip-enhanced near-field infrared (IR) nano-optics system capable of both "writing" & "reading" information at a resolution of ~ 35 nm (i.e., a storage capacity of ~ 64 GB inch-2). Moreover, thanks to the fine biological compatibility of silk protein, the silk-drive can store biological information, which can not be achieved by traditional semiconductor-based hard disks. Our method promises great potential in the local-manipulation of optically and/or biologically functional devices and unravels a novel way to perform nanometric and "green" photolithography in biomaterials.