Fig. 1: Design and characterization of the SCEAs.

a–c Schematics showing the design of the SCEAs for minimally invasive and large-scale intracranial brain activity mapping. d Expanded schematic view of the layered structure of the SCEAs. e, f Optical images of a SCEA in the compressed and deployed states. Scale bar, 5 mm. g In vitro impedance map of a 64-channel SCEA with 100 × 100 μm² active sites before and after one shape transformation cycle (compression and expansion), measured at 1 kHz. h Boxplots (n = 169 from 3 devices) showing the distribution of the 1 kHz-impedance values measured before and after one shape transformation cycle (compression and expansion). The active sites have a dimension of 100 × 100 μm². The box plots show the median and quartile range, and the whiskers denote 1.5× the interquartile range. Individual data points are overlaid on the box plots. i An optical image showing the small cranial opening in a rat for SCEA strip insertion. Scale bar, 1 mm. j A SCEA implanted epidurally into a rat brain through minimally invasive surgery. The skull was removed after completing the SCEA implantation process for visualization. The right picture shows the designed pattern of the SCEA. Scale bar, 1 mm. k The cortical surface of a rat which was under a SCEA implanted through minimally invasive surgery. The dashed box shows the outline of the SCEA, which was removed for better visualization of the cortical surface. Scale bar, 1 mm. Source data are provided as a Source Data file.