Conducting hydrogels for edible electrodes.

Area of Science:

• Materials Science
• Biomedical Engineering
• Food Science

Background:

• Advancing edible device research requires highly swollen, strong, and conductive hydrogel materials.
• Existing materials often lack the necessary properties for safe and effective integration into edible electronics.

Purpose of the Study:

• To develop a simple method for producing conductive, edible hydrogels using gellan gum and gelatin.
• To evaluate the electrical properties of various food-grade products as potential edible electrodes.
• To demonstrate a functional edible capacitive pressure sensor for potential gastrointestinal applications.

Main Methods:

• Fabrication of gellan gum/gelatin ionic-covalent entanglement (ICE) hydrogels with incorporated NaCl or CsCl.
• Measurement of hydrogel conductivity.
• Analysis of electrical properties of food-grade materials (alginate-gelatin hydrogels, Vegemite, Marmite, jelly, gold leaf).
• Construction and testing of an edible capacitive pressure sensor using ICE gels.

Main Results:

• ICE gels with NaCl and CsCl achieved conductivities of 200 ± 20 mS cm⁻¹ and 380 ± 30 mS cm⁻¹, respectively.
• Alginate-gelatin hydrogels, Vegemite, Marmite, jelly, and gold leaf were assessed for their electrical properties as potential edible electrodes.
• The developed edible capacitive pressure sensor exhibited a sensitivity of 0.80 ± 0.06 pF kPa⁻¹ within a 4-20 kPa range.

Conclusions:

• Conductive, edible hydrogels can be successfully fabricated using a gellan gum/gelatin ICE approach.
• The developed hydrogels and tested food-grade materials show potential for creating edible electronic devices.
• The edible pressure sensor demonstrates feasibility for detecting physiological pressures within the gastrointestinal tract, potentially aiding in diagnosing motility disorders.