Zwitterionic Soy Sauce Based Gel Electrolyte for Edible Supercapacitors

With the swift advancement of technology, the use and dependence on small and miniaturized electronics have grown substantially. Common power sources for wearable and implantable devices often contain potentially harmful materials, leading to significant environmental issues and waste that demand innovative and sustainable solutions, particularly in the Internet of Things era. In addition to new biodegradable and implantable devices, the emergence of edible and ingestible electronic devices offers a niche, sustainable solution. To make these devices viable, their energy sources must also be edible and ingestible. Here, zwitterionic and edible gel electrolytes are produced using hydroxyethyl cellulose and commercial soy sauce (shoyu) for superior ionic conductivity, providing a favorable environment for L929 proliferation [1]. These edible gels are combined with carbon electrodes to fabricate edible supercapacitor devices, resulting in an ideal double-layer capacitance with a maximum specific capacitance of 3.75 F g⁻¹ and a capacitance retention of 86.5% after 10000 cycles. Fabricated edible supercapacitors can be flexed and even rolled smoothly. Gels showed a substantial resistance to drying and freezing due to the presence of the zwitterionic structure of soy proteins in soy sauce. Degradation studies using a simulated gastric fluid have also shown that all components of the edible supercapacitor can be digested within 40 min. Presenting an edible gel based on soy sauce with remarkable ionic performance offers a compelling alternative to traditional energy storage devices. This innovation paves the way for advancing state-of-the-art ingestible healthcare devices and environmentally sustainable electronics.<br/><br/>[1] An Edible Supercapacitor Based on Zwitterionic Soy Sauce Based Gel Electrolyte, M.B. Durukan, D. Keskin, Y. Tufan, O. Dincer, M. O. Cicek, B. Yildiz, S. Cinar Aygun, B. Ercan, H. E. Unalan, Advanced Functional Materials 34 (2024) 2307051.