Fig. 2: Fabrication and characterization of the flexible electrode array.

a Optical image and the exploded view of the electrode array. Scale bar, 3 mm. The electrode array consisted of screen-printed conductive inks as the electrochemical electrode interface, copper wires and copper spots as the conductive tracks, and PI and PDMS films as the substrates and encapsulations. The flexible electrode array was miniaturized, ultrathin, and lightweight, which could conformally interface on the tooth. b Mechanical deformations of the flexible electrode array including bending and stretching. c Schematic of multilayer modification of the electrodes in an exploded view. d Scanning electron microscope (SEM) image of polyaniline (PANi) modified electrode. Scale bar, 100 nm. e SEM image of polypyrrole (PPy) modified electrode. Scale bar, 1 μm. f Energy dispersive spectroscopy (EDS) images of polypyrrole/fluoride (PPy/F) electrodeposited on the working electrode of the drug delivery module, including C (red), N (green), and F (blue) elemental mapping.