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Salvador Moreno1 Manuel Quevedo-Lopez1 Majid Minary1

1, University of Texas at Dallas, Richardson, Texas, United States

With great progress in the field of implantable electronics, pushing towards an integration of technology with people, the biocompatibility of those electronics is a key issue. Collagen, one of the most abundant proteins in mammalian tissues, is a well-known biomaterial used in tissue engineering and bone scaffolds. Previous work has shown that collagen1 can be used as a substrate for flexible electronics made using with E-Beam deposition by shadow mask. However, in order to make more advanced electronic devices, manufacturing strategies need to be developed in order to overcome limitations of collagen, namely temperature and mechanical stability in water. Transfer printing of electronics is one such strategy, using sacrificial layers of PMMA, however these also have their own temperature limitations. Germanium oxide is presented in this paper as novel water based sacrificial layer, which is amenable for high temperature processes such as the annealing and doping of Zinc Oxide (ZnO) via Pulse Laser Deposition. Some of the devices presented in this study include capacitors, transistors, and an integrated inverter transistor circuit. After etching in water overnight, devices made on wafers are lifted off and transferred to collagen films. By using cross linkers such as Riboflavin (Vitamin B2) and, a photochemical initiator, in the presence of blue light, devices built on collagen films can be programmatically enhanced to resist enzymatic digestion. Cross-linked collagen was shown to have enhanced mechanical and thermal properties while maintaining biocompatible aspects. Encapsulated integrated electrical devices transferred onto collagen were shown to have minimal effects on cell viability on assays on MC3T3 osteoblast and a549 epithelial cells. Together, this study demonstrates a manufacturing strategy of developing biocompatible integrated electrical devices on collagen.

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