Fig. 4: Connecting the artificial neuron to a biological cell.

a (Top) Schematic of seeding cardiac cells (cardiomyocytes) on an ultra-flexible and releasable mesh sensing system. (Bottom) Schematic of forming 3D mesh-tissue integration. b Fluorescence optical image of a formed mesh-tissue. The red color indicates the embedded mesh ribbons. The green, blue, and purple colors indicate F-actin, 4′,6-diamidino-2-phenylindole (DAPI), and cardiac Troponin T (cTnT) in the cells, respectively. Scale bar, 0.5 mm. c Representative recordings from four graphene sensors integrated on a mesh embedded in a tissue. The sharp spikes and broad peaks correspond to electrical action potentials and mechanical contractile signals, respectively. d Schematic of the cell-sensor interface in the mesh-tissue system. The acquired sensing signals are amplified and fed into the artificial neuron, analogous to that presynaptic signals are transmitted by a synapse to the postsynaptic neuron. e Sensing signals (f ~ 0.4 Hz) recorded from a cell in a mesh-embedded tissue (top panel) were converted into voltage pulses (120 mV, 70 ms, middle panel) and fed into the artificial neuron, which remained silent (bottom panel). f Sensing signals of increased frequency (f ~ 0.6 Hz) from the cell after the tissue was treated with norepinephrine (top panel) were converted into voltage pulses (120 mV, 70 ms, middle panel) and fed into the artificial neuron, which showed firing activities (bottom panel).