Conducting hydrogels for edible electrodes
The development of highly swollen, strong, conductive hydrogel materials is necessary for the advancement of edible device research. Using a gellan gum/gelatin ionic-covalent entanglement (ICE) hydrogel, a simple method of producing conductive, edible hydrogels is described. ICE gels containing NaCl or CsCl were developed which exhibited conductivities of 200 ± 20 mS cm−1 and 380 ± 30 mS cm−1, respectively. Furthermore, the potential of food grade products for use as edible electrodes was examined by analysing the electrical properties of alginate-gelatin hydrogels, Vegemite, Marmite, jelly and gold leaf. Lastly, these edible ICE gels were used to demonstrate a capacitive pressure sensor from consumable materials, which displayed a sensitivity of 0.80 ± 0.06 pF kPa−1 for a range of 4-20 kPa. The pressure exerted by the GI tract on its contents is standardly 0.7 kPa to 6.3 kPa. This suggests potential for application in the detection of digestive pressure abnormalities such as intestinal motility disorders.