Asst. Prof. Hemi Rotenberg
David Wang Auditorium, 3rd floor Dalia Meidan Bldg.
Traditional methodologies for bio-electrical interrogation are associated with interconnected leads and substrate-bound electrodes, which are mechanically invasive and lack intra-volumetric access. Thus, semiconductor junctions have been recently used to optically trigger biological modulation via photovoltaic or photoelectrochemical mechanisms. The creation of heterojunctions typically involves materials with different doping or composition, which leads to high cost, complex fabrications, and potential side effects at biointerfaces. Here we show that a porosity-based heterojunction, a largely overlooked system in materials science, can yield an efficient photoelectrochemical response from the semiconductor surface. Using self-limiting stain etching, we create a nanoporous/non-porous, soft–hard heterojunction in p-type silicon within seconds under ambient conditions. Upon surface oxidation, the heterojunction yields a strong photoelectrochemical response in saline. Without any interconnects or metal modifications, the heterojunction enables efficient non-genetic optoelectronic stimulation of isolated rat hearts ex vivo and sciatic nerves in vivo with optical power comparable to optogenetics, and with near-infrared capabilities. Moreover, we will describe some nanoscale biointerfaces using silicon nanowires for biomodulation with high precision and sub-micron resolution.