3D Printed Edible Hydrogel Electrodes

We report on a hand-held reactive printing device used to pattern highly conductive, edible hydrogel wires formed from gellan gum, gelatin, cross-linkers and a common salt (NaCl). The conductivity of the gels when printed (190 ± 20 mS/cm) closely matched the conductivity recorded for cast systems (200 ± 19 mS/cm). Printing was observed to reduce the elastic modulus and failure strains of hydrogels under compression, but printed gels retained sufficient integrity for application as flexible conductive lines. We demonstrate that hand-held printing can utilize to pattern soft conductor elements within a simple electronic circuit.