Fig. 21.

(a) Schematic view of experimental procedures for energy-harvesting optogenetic brain stimulation. (b) Implantation of f-μLED array underneath the mouse skull for stimulation of M1 (As a red light-activated channelrhodopsin variant, Chrimson was expressed in the primary motor cortex). (c) i) Video snapshot tracking the whisker movements. The tracking point is shown as a yellow circle. ii) Relative whisker movements via f-μLED stimulation with the operation of MMTENG. (d) Confocal fluorescent images of the mouse brain. The top is the expression of Chrimson and the stimulation site in the motor cortex, whereas the bottom is a magnified image for the stimulated M1 site. Red color signals indicate the expression of tdTomato (a maker of Chrimson), and the blue signals represent the DAPI (a maker of neural cells). © 2020 Elsevier Ltd. Reprinted with permission from Ref. [212].