Thermally Healable Food-Based Conductive Oleogel Ink with Added Edible Gold-Leaf Powder

Abstract

Edible electronics, a nascent technology utilizing food-derived materials, are safe to ingest, are environmentally friendly, and can be broken down or even digested in the body after performing their function. They can be realized by creating dielectrics, insulators, semiconductors, and conductors from soft food-derived materials and integrating them into devices. In particular, a great expectation is placed on conductive materials, which are the core of electronic components. In this study, a thermally healable, three-dimensional (3D) printable conductive oleogel ink�composed of food-based materials�is proposed. The oleogel is a mixed paste formed by adding activated charcoal (AC) and gold-leaf powder to an oleogel matrix consisting of beeswax and olive oil. The resulting oleogel has a useful property: it can be liquefied by heating and solidified by cooling. By selecting olive oil, which is a non-drying oil, as the oil contained in the oleogel, we expect the oleogel to feature a thermal healing property and ease of painting. Furthermore, AC, which is conductive when densely packed, and gold leaf, which has high conductivity and many contact surfaces, are combined with the oleogel. By investigating the mixing ratio of these ingredients, we provide the criteria for improving the thermal healing and 3D-printing capabilities and the electrical conductivity of food-derived organic−inorganic composite materials. Such functional oleogels would enable the emergence of future products naturally compatible with humans in the healthcare, medical, and food industries.

Thermally Degradable Split-Ring Resonator Made on a Gelatin Substrate with Enhanced Dielectric and Conductive Properties

“…A safer solution is edible electronics made from edible materials that can be digested or excreted after performing their function. Although ingestible ingredients have constraints, including an upper limit of intake, researchers have explored the suitability of using materials, e.g., gold , or activated carbon , as conductors, β-carotene as a semiconductor, and cellulose as an insulator, in transistors, inductors, and capacitors . They have also examined wireless measurement systems that work by using capacitive coupling or magnetic field coupling , and that are made from edible or potentially edible materials.…”

Degradable Superhydrophobic Coatings Using the Solid–Liquid Transition of a Multilayer Structure near Body Temperature

“…14 Recent advances have led to edible smart surfaces 15 with hydrophobic natural waxes, which are approved by the U.S. Food and Drug Administration, and the brittleness of these coatings has been decreased 16,17 with a diatom shell, 18 chitosan, 19 cellulose, 20 ectin, 21 oils, 22 and attapulgite. 23,24 Although these coatings would be useful as protective films for drug delivery 25 and edible electronics, 26,27 their wax materials have high melting points, e.g., approximately 61−65 °C for beeswax, and cannot be dissolved in the body. Thus, what is needed is a film designed to be degradable in the body.…”