Fig. 1: Diagram of electrochemical electrode-integrated in vitro platform and its potential utility to study the GBA.

a Diagram of GBA physiology, depicting communication between the ENS and the brain (left). Diagram of luminal stimulation of enterochromaffin cells in the gut epithelium and subsequent basolateral 5-HT secretion to activate enteric nerves (right). b Conceptual diagram of how 5-HT would be detected from cultured gut cells in our platform. The cross-section is shown of our 3D-printed transwell system containing the (i) top chamber, (ii) bottom chamber, (iii) porous PETE membrane with integrated electrodes, (iv) external contacts, and (v) fluid inlet channel. The cyclic voltammetry (CV) electrodes are shown on the bottom side of the porous membrane to separate the cells from electronics via the insulating porous membrane. c Conceptual CAD diagram showing the 3D arrangement of the chambers sandwiching the electrode-integrated membrane. Cells grown on the membrane and basolaterally secreted 5-HT are shown in blue. d Image of a 3D-printed platform with pogo-pin connections at the contact pads used for testing in this paper. e CAD diagram of porous membrane fabricated with the CV three-electrode system. The sensing area is denoted with a circle, showing the hydrated part of the membrane that will be exposed to chemicals and eventually host a stable cell culture