UC Irvine

Biomolecular proton conductors are promising candidates for the development of environmentally friendly and biocompatible electronics. In particular, structural proteins derived from optically-active cephalopod skin cells, called reflectins, are remarkably attractive for this purpose due to their unusual sequences predominantly composed of charged residues, self-assembly properties, responsiveness to stimuli, and high proton conductivities. However, our inability to scale-up the production of reflectin-based devices and our limited mechanistic understanding of proton conduction mechanisms in this class of proteins, fundamentally restrict the practical application of reflectin-based bioelectronics devices. Herein, we describe an inkjet printing methodology for the large-scale fabrication of reflectin-based proton-conducting devices. First, we develop a water-based reflectin solution, which is compatible with commercial inkjet printers, thereby enabling the devices to be directly interfaced with both electronics and biology. Next, we print devices with controlled geometries of the reflectin films. We then electrically characterize the printed reflectin-based devices and confirm that this commercially feasible device fabrication technology yields devices with high proton conductivities. Overall, our findings highlight the potential of printable reflectin devices and establish inkjet printing as a reliable strategy for the large-scale production of protein-based bioelectronic devices, which may allow a broader range of applications in the field of low-cost, flexible, and large-area electronics.