Biocompatible, Inkjet Printed Heterostructure Photodetector for Biosensing Applications

Age-related macular degeneration (AMD), a retinal degenerative disease that results in a continuous degeneration of photoreceptors in the retina which eventually leads to complete blindness [1]. One approach to combat AMD is through the use of artificially implantable photodetectors that are physically placed on the retina. The large format photodetector pixels on the flexible and conformable substrate allows the implantable photodetectors to be in intimate contact to retinal pigment epithelium. Interestingly, 2D materials such as photosensitive and semiconducting molybdenum disulfide (MoS
₂
) and electrically conducting graphene have recently received tremendous promise due to their unique photonic and optoelectronic properties properties and their potential in various types of micro and nano devices [2,3,4]. In this study, we have tested the biocompatibility of various 2D materials, such as graphene and MoS
₂
in several organic solvents. Specifically, these materials have been dispersed in Isopropyl Alcohol (IPA), a mixture of Cyclohexanone/Terpineol 7:3 ratio (C/T), and N-Methyl-2-pyrrolidone (NMP). Mouse Embryonic Fibroblast (STO) was used for the biocompatibility analysis for inks drop cast on flexible polyimide substrate. A biocompatible photodetector on a flexible polyimide substrate was designed, fabricated using inkjet printing and tested as a function of photo intensity and strain.