Silicon membranes and nanowires for bio-electric interface at the whole organ, intercellular, and subcellular level

Traditional methodologies for bio-electrical interrogation are associated with interconnected leads, which are mechanically invasive and lack intra-volumetric access. Optogenetics, however, requires genetic modification, which limits its translational applications. We propose optically sensitive silicone-based materials to perform leadless, minimally invasive photo-electrical modulation from the organ to the subcellular level.

For cardiac optical pacing, we used 1-micron thick single crystalline silicon membranes, which were flexible and able to confirm and wrap around the contractile heart. We then performed photo-pacing of the heart and achieved 1:1 capture using ~95mW/cm² and 10ms laser pulses. We photo-paced the heart from both the right and left ventricles, which demonstrates its feasibility for cardiac resynchronization therapy applications.

For subcellular modulation, we hybridized myofibroblasts with silicon nanowires by spontaneous internalization. Then, we performed intracellular local photo-thermal stimulation with subcellular resolution by applying focused laser to the nanowires. We then used these hybrids to address the long-standing debate of whether myofibroblasts electrically couple with cardiomyocytes in vivo. We injected the hybrids into the left ventricular wall and showed that they establish a seamless integration with the native heart in vivo. We then harvested the heart and applied local, cell-specific photo-stimulation of the pre-hybridized cells. As opposed to our in vitro findings where the hybrids electrically couple to cardiomyocytes, we found no evidence for in vivo coupling as no calcium propagation was observed from the stimulated myofibroblasts to the native tissue. This methodology can be further used for both in vitro and in vivo scenarios where intracellular, or cell-specific interrogation is required.