(A) Ultra-small 3D transistor probes for intracellular recording. (Top
left) Optical image of 3D transistor probes with magnified view (inset) showing
that the U-shaped nanowire is transferred onto the device tip. (Bottom left)
Optical image of the bend-up device array in water. (Right) Plot of maximum
spike amplitude obtained from action potential recordings in dorsal root
ganglion neurons using the ultra-small 3D transistor probes. The
P values of the statistical studies were obtained using
Student’s t-test. *P < 0.1,
****P < 0.0001. Adapted, with permission, from
[30]. (B) Mesh electronics for
chronic recording in retina from awake mice at the single-neuron level. (Top
left) Ex vivo imaging of the interface between the retinal
ganglion cells (green) and injected mesh electronics (red) on day 7 after
injection (top view). (Bottom left) Side view image of the interface. (Right)
Plots showing the firing events of two neurons (red and green) in response to
grating stimulations on day 7 after injection. Shaded regions (orange)
correspond to times when gratings stimulations were performed. Adapted, with
permission, from [53]. (C) Wireless
optoelectronic photometer neuron recording in deep brain. (Top left) Colorized
scanning-electron-microscopy (SEM) image of the probe. (Bottom left) Schematic
of a GaAs μ-IPD with a representative SEM image of μ-IPD in the
right corner. (Top right) Plot of fluorescence changes before/after animal was
shocked with wireless optoelectronic photometers. (Bottom right) Heatmap of
signals (eight trails) recorded before/after animal was shocked. Heatmap is
aligned with plotted trace. Adapted, with permission, from [62]. (D) Flexible polymer fibers capable of
collocated neural recordings. (Top left) Photograph of a bundle of multimodal
fibers (before etching of the sacrificial polycarbonate cladding). (Bottom left)
Cross-sectional image of the multimodal fiber. (Right) Electrophysiological
recording plots of optically evoked potentials in the medial prefrontal cortex
of wild type mice performed at 1 month and 3 months after the one-step
implantation and transfection surgery. Adapted, with permission, from [64]. Abbreviations: COC, Cyclic olefin
copolymer; FET, field-effect transistor; gCPE, conductive polyethylene (CPE) and
5% graphite; PC, polycarbonate.