Fig. 1: Printing of soft neural probes.

a Schematic illustration of a printing system of liquid metal. b Photograph and SEM of printed liquid metal patterns with various lengths. Scale bars, 500 µm (black) and 50 µm (white). c Line-widths of printed liquid metal as a function of an inner diameter of the nozzle. Each data point indicates the average of five measurements, and error bars represent the standard deviation. d Schematic illustration of a structural similarity between the soft neural probe and neuron. Inset: the schematic illustration of exploded view of soft neural probe. e Colorized SEM of a tip part of the soft neural probe. Green and yellow colors correspond to parylene and PtB, respectively. Scale bar, 10 µm. f SEM of the PtB deposited on the tip part of the soft neural probe. Scale bar, 500 nm. g Impedance spectroscopy of pristine EGaIn and PtB-coated EGaIn. Inset: Impedance values of PtB/EGaIn and EGaIn at 1 kHz. Error bars represent the standard deviation (n = 10). h Comparison of elastic moduli of silicon, gold, PEDOT, Parylene/EGaIn, and PtB/EGaIn. Error bars represent the standard deviation (n = 5 independent samples). i Real-time change in resistance of a PtB/EGaIn during its disconnection and coalescence. j Impedance spectroscopy of PtB/EGaIn during repeated disconnection and coalescence.