Microscopic Projection Lithography for Integrating Metallic Microstructures on Silk Protein for Biodevice Applications

Precise patterning of metallic micro/nanostructures enables application of silk protein in biomedical devices with a seamless human–machine interface. However, high-quality, expensive equipment and facilities involved in micro/nanofabrication hinder rapid prototyping for explorative laboratory-based research. Here, we report cost-effective and high-resolution light-emitting diode-based projection lithography methods for fabricating a Cr photomask and metallic microstructures on a silk protein layer. After two-step photolithography performed using a commercial camera and microscopic objective lens, inkjet-printed patterns are successfully projected on the silk layers with 100× and 500× demagnification ratios. A lift-off process is conducted to integrate Au patterns on the lithographic-patterned resist/silk layer, and various Au microstructures with sizes