Multifunctional Three-Dimensional Nanoelectronic Networks for Smart Materials and Cyborg Tissues

Abstract

Nanomaterials provide unique opportunities at the interface between nanoelectronics and biology. “Bottom-up” synthesized nanowire(NW) with defined functionality can be assembled and enabled into three-dimensional(3D) flexible nanoelectronic networks. The micro- to nanoscale electronic units blur the distinction between electronics and cells/tissue in terms of length scale and mechanical stiffness. These unconventional 3D nanoelectronic networks can thus provide a path towards truly seamless integration of non-living electronics and living systems. In this thesis, I will introduce a general method for fabricating 3D macroporous NW nanoelectronic networks and their integration with hydrogel, elastomer and living tissues, with an emphasis on the realization of two-way communication between active nanoelectronics and the passive or living systems in which they are embedded. First, fabrication of 3D macroporous NW nanoelectronic networks will be described. Examples showing hundreds of individually addressable, multifunctional nanodevices fully distributed and interconnected throughout 3D networks will be illustrated. Proof-of-concept studies of macroporous nanoelectronic networks embedded through hydrogels and polymers demonstrate the ability for dynamically mapping pH gradients and strain fields. Second, a universal method to improve the long-term stability of semiconductor NWs in physiological environments using atomic layer deposition(ALD) of dielectric metal oxides shells on NW cores will be introduced. Long-term stability improvement by ALD of Al2O3 shells with different shell thickness and annealing conditions will be described and discussed. In addition, studies of semiconductor NW nanodevices with multilayer Al2O3/HfO2 shells indicates stability for up to two years in physiological solutions at 37◦C. Third, 3D macroporous nanoelectronic networks were integrated with synthetic cardiac tissues to build “cyborg” cardiac tissues. Spatiotemporal mapping of action potential(AP) propagating throughout 3D cardiac tissue was carried out with sub-millisecond time resolution, allowing investigation of cardiac tissue development and responses to pharmacological agents. These results have promised the applications of cyborg tissues in the fields ranging from fundamental electrophysiology and regenerative medicine to pharmacological studies. Finally, multifunctionallities of nanoelectronic devices for applications at the bio/nano interface will be discussed. Incorporation of NW field-effect-transistor(FET) and electrical stimulators in macroporous nanoelectronic networks demonstrates simultaneous recording and regulation of AP propagation in cyborg cardiac tissues. In addition, a convexed-NW FET bioprobe has been developed for simultaneous detection of AP and contraction force from individual cardiomyocyte. These explorations on the nanoelectronics functionalities highlight the capability to enable new communication modes between electronics and living tissues.