Flexible and Waterproof Resistive Random-Access Memory Based on Nitrocellulose for Skin-Attachable Wearable Devices

Memory for skin-attachable wearable devices for healthcare monitoring must meet a number of requirements, including flexibility and stability in external environments. Among various memory technologies, organic-based resistive random-access memory (RRAM) devices are an attractive candidate for skin-attachable wearable devices due to the high flexibility of organic materials. However, organic-based RRAMs are particularly vulnerable to external moisture, making them difficult to apply as skin-attachable wearable devices. In this research, RRAMs are fabricated that meet the requirements for skin-attachable wearable devices using a novel organic material, nitrocellulose (NC), which is biocompatible with high water-resistance and high flexibility. The fabricated NC-based RRAMs show a stable bipolar resistive switching characteristic. In addition, the formation of a native Al oxide between Al and NC is verified, which is the source of the bipolar switching characteristic of NC-based RRAMs. Furthermore, electrical and chemical analysis is conducted after dipping and submersion into various solutions as well as deionized water to confirm the water-resistance of the NC-based RRAMs. Finally, it is also confirmed that NC-based RRAMs are suitable for use in skin-attachable wearable devices through a flexibility test. In conclusion, this study suggests that NC-based RRAMs can be applied in skin-attachable wearable devices, simplifying healthcare in the future.