Fig. 1: Conformable devices can be surgically implanted on top of the submucosal plexus of the colon.

a Brightfield image taken in transmission showing the device layout for accessing the ENS. Devices consist of gold tracks insulated with parylene-C with poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-coated gold electrodes, containing a central array of 28 recording electrodes, each 20 µm in diameter, flanked on either side by a pair of large electrodes, 200 µm in size, which are wired but were used as surgical markers. Given that the device substrate (parylene-C) is translucent, the outline of the device has been highlighted in orange. b Photograph of device with bonded flat flexible cable (FFC) for connection to Intan recording system. Device is situated on a glass slide in this image for transport, but is removed for implantation. Black box indicates the region of device shown in a. Loops designed into the device for suturing are visible on the left, outside the black box. c Schematic detailing recording electrode layout, where electrodes are arranged as a linear array of 7 tetrodes, with each electrode separated by 50 µm from its tetrode neighbors. d–h, Steps for implanting the device into the colonic wall, images taken via stereoscope during surgery. Top shows surgical images of the steps, and the bottom shows a representative schematic for each image. Dotted line in d indicates the periphery of the section of colon under analysis. Brackets in e indicate the section of the needle that is situated in the wall of the colon. Brackets in (f, g) indicate the section of forceps that are within the wall. Dotted line in (g), highlights the outer edges of the implant. Brackets in (h, i) show the section of the implant that is in the colonic wall. Inset from (h) in the blue box is shown in (i) with the device situated beneath the muscularis externa. Dotted lines indicate where the device enters (bottom dotted line) and exits (top dotted line) the tissue. j Hematoxylin and eosin histological stain of needle placement in colonic wall, which is used to create the tunnel for the implant, as shown in (e). This image shows implantation directly below the muscularis externa. Asterisk indicates the tunnel in the tissue where the needle was threaded through the colonic wall. The lumen of the gut, which contains fecal matter, is shaded in gray.