Biodegradable resistive switching devices made from carrageenan insulator and carrageenan substrate

Carrageenan material, which is extracted from red edible seaweed, has been widely used in the food and other industries as a thickener and stabilizer. In this paper, carrageenan is employed for the first time as a resistive memory device structure for both the resistive layer and substrate. The carrageenan substrate (CS) has the advantages of excellent optical transparency, low cost, abundant sources, being skin friendly, and biodegradability. Owing to the excellent bending ability of the CS, the In/carrageenan/Ag/CS memory device (ICAC) can fit closely to human skin. The fabricating process for the ICAC device does not involve a vacuum system. The ICAC device shows promising resistive switching behavior with a high ON/OFF ratio of over 106 and a uniform distribution of switching parameters. Furthermore, when carrageenan is used for both the resistive layer and substrate, this produces strong interfacial adhesion. The good matching of metal-insulator-metal (MIM) structures with flexible substrates enhances the strength of the device structure and result in good bending performance. Supported by convincing physical and electrical evidence, the good uniformity and bending performance of the ICAC device may be related to the ability of the Ag ions (from the bottom electrode) to migrate by interacting with the functional groups of the carrageenan and create Ag filaments. Understanding the underlying switching mechanisms of carrageenan memory devices may enable a new design space for transient resistive-switching memory. This demonstration of a skin-inspired biodegradable carrageenan memory device shows great potential for application in wearable biomedical devices, artificial electronic skin, and even implantable electronics in the foreseeable future.