Fig. 4: Soft, conformable, and transient electrode arrays for neural and cardiac diagnosis and therapy.

a Schematic illustration of a 5 × 5 transient epidural electrode array capable of electrocorticography (ECoG) monitoring and electrical neurostimulation, and an optical image of the active region of a representative device in the inset. b Photographs of gold (Au)-based (left hemisphere) and soft, conformable transient (right hemisphere) neural electrode arrays implanted onto cortical surfaces in left and right hemispheres of a rat, respectively, with the inset showing a custom-designed skull cap for stable, long-term implantation. c Comparative analysis of recorded ECoG signals from the Au and transient neural electrodes during normal and acute seizure activities. d Long-term, stable ECoG measurements with soft, transient neural electrodes implanted in rat models over several weeks. e Power spectral density (PSD) analyses of the recorded signals. Data are presented as mean values ± standard deviation. n = 3 biologically independent animals per group. f Spatiotemporal mapping of ECoG biopotential patterns, revealing distinct spiking flows during a seizure. g Schematic of the experimental setup for neural recording and stimulation (left), and ECoG traces recorded during a seizure before and after electrical stimulation (E/S) (right). h Comparison of the average count/amplitude of spiking events before and after electrical stimulation. Data are presented as mean values ± standard deviation. n = 5 biologically independent animals per group. i Time-frequency analysis of ECoG signals before and after drug injection and electrical stimulation.