Fig. 3

Precision neural stimulation. a Schematic illustration of precision neural stimulation by optomechanical bio-dart. The mechanical stimulation on cell membrane results in the activation of Piezo1 channel, with increasing in Ca²⁺ influx and inward current. b The bright field (left) and fluorescent (right) images of neural cell with Piezo1 channels identified in fluorescence green, and the nuclei in blue. c Microscopic images showing shooting of dart toward a single neuronal cell. Yellow arrow indicates the dart. d, e Fluorescent images showing intracellular Ca²⁺ response of a target single HT22 cell after stimulation. Cells in (e) were modified with GsMTx4. f Normalized fluorescence intensity of intracellular Ca²⁺ for neuronal cells with different stimulation as a function of time. g Fluorescence intensity change of stimulated cell as a function of dart velocity. h Microscopic image showing single-cell electrophysiological experiment for recording inward current of target stimulated neuronal cell using patch clamp. i Representative recorded inward current of stimulated HT22 cell and overexpressing Piezo1 HT22 cell with different stimulation velocity. The shading curves are the raw measured data, while the black, red, and blue curves are the fitting data. j Maximal inward current (I_max) as a function of different stimulation velocity. k Inward current recording for repeated stimulation of HT22 cell, inset shows the quantitative analyses of the recorded maximal inward current of two different stimulation. Red curves show the boundary of target cell with stimulation, while white curve shows the neighboring cell without stimulation. The red and yellow arrows indicate 808 nm laser and dart, respectively. Scale bars: 20 µm