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. Author manuscript; available in PMC: 2018 Aug 19.
Published in final edited form as: Nat Nanotechnol. 2018 Feb 19;13(3):260–266. doi: 10.1038/s41565-017-0041-7

Figure 5. The mechanism of coaxial nanowire photocurrent generation and neuronal modulation is primarily photoelectrochemical, aided by surface atomic Au.

Figure 5

(a) Schematic of temperature measurement setup for simultaneous measurement of temperature and neuronal APs produced by laser stimulation or injected current through patch amplifier. (b) Patch clamp electrophysiology current clamp trace of membrane voltage (top) in DRG neuron stimulated by injected current (blue pulse) and illuminated by a 532 nm laser pulse at the neuron-PIN-SiNW interface (green bar). Corresponding temperature measurement (bottom) taken 2 μm away from neuron/PIN-SiNW interface produced by calibrating the thermometer pipette resistance with temperature changes. This is a representative temperature measurement from one of 18 total traces from 3 independent neurons. (c) Photocurrent measurement taken from a single p-type SiNW illuminated with 532 nm laser light for 10 ms at a laser illumination power of 85 mW (top). This is a representative trace from one of a total of 71 traces measured from 4 independent p-type SiNWs. Photocurrent measurement taken from a p-type SiNW with diffused Au for 10 ms at laser illumination powers of 8.5 mW (blue) and 6.8 mW (green). These are representative traces from a total of 52 traces measured from 6 independent p-type SiNWs with diffused Au. (d) Patch clamp electrophysiology current clamp trace of membrane voltage (top) in DRG neuron stimulated by injected current (blue pulse) and illuminated by a 1 ms 17.4 μJ 532 nm laser pulse at the neuron-p-type SiNW with diffused Au interface (green bar). This is a representative trace from one of a total of 40 traces measured from 5 independent neurons. (e) Band diagram representing the redox reaction that occurs at the interface between the PIN-SiNW and the electrolyte solution. Kinetic barrier for photoelectrochemical reaction is lowered by the presence of atomic Au. Green arrows represent the light stimulus. Grey arrow shows the excitation of electrons from the valence to the conduction band. Grey dashed lines represent Fermi levels in dark.