Fig. 4: In vivo neural stimulation of peripheral nerve.

a, Schematic diagram of the acute stimulation experiments. A TIME array is implanted in the sciatic nerve of the rat crossing the peroneal and the tibial fascicles. The axons innervating the TA muscle are in the peroneal fascicle, whereas the axons innervating the GM and PL muscles are located in the tibial fascicle. Biphasic pulses of 100 µs per phase and increasing intensity were injected independently at the nine microelectrodes (diameter, 25 µm) present in the device. The local electrical stimulation can depolarize the nerve fibres in its vicinity and trigger the electrical activity of the muscles, which is recorded with needle electrodes. b, Optical micrograph of the implanted TIME device in the sciatic nerve. c, CMAPs recorded from TA, GM and PL muscles in response to increasing levels of injected current pulses applied to one of the electrodes. d, Recorded CMAPs in TA, GM and PL muscles in response to trains of biphasic current pulses of increasing amplitude applied to nine microelectrodes of the array (A1–A9). e, Normalized CMAP of TA, GM and PL muscles in response to pulses injected to microelectrodes A5–A7 from the implanted TIME. f, Comparative plot of the injected current needed to elicit 5% and 95% of the maximum CMAP using microelectrodes of EGNITE (cyan, n = 4) and of iridium oxide (grey, n = 6)⁴⁸. *P = 0.039, **P = 0.0032 (two-way ANOVA followed by Bonferroni post hoc test for differences between groups). g, Comparative plot of the selectivity index at the minimal functionally relevant muscular stimulation for the same data as in f⁴⁸. In f,g, data are mean ± s.e.m.