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

Abstract

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 skinattachable 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.

Recent advances in organic‐based materials for resistive memory applications

“…Extensive studies have revealed that organic small molecules could be applied as excellent resistive memory materials, attributing to their advantages of low cost, light weight, mechanical flexibility, and ease of processing 47,48,66,70,83‐104 . Many organic small molecules have been reported to exhibit resistive switching characteristics, including the binary and even higher multilevel nature 70,83‐96,105,106 .…”

“…In addition, their optoelectronic properties can be easily modulated by molecular design‐cum‐synthesis strategy, which opens up possibilities of achieving diverse memory functions 41‐44 . Their intrinsic flexibility and softness also endow them superior ability for stretchable and wearable electronics, 45‐47 which can bring us closer to the future artificial intelligent lifestyle. Thanks to these charming advantages, numerous research efforts have been devoted to seeking for high‐performance organic‐based data storage materials and devices.…”

Structural Analysis and Performance in a Dual‐Mechanism Conductive Filament Memristor

“…Recently, most of the switching behaviors of RRAM devices have been investigated through electrical measurements and simulation approaches, resulting in an insufficient understanding of their fundamental science. [26][27][28] Therefore, a novel technique for the investigation of the switching mechanism is urgently needed. High-resolution transmission electron microscopy (HRTEM) possesses high spatial resolution and reveals microstructure at the atomic scale, providing direct evidence of relations between performance and microstructure.…”

Improvement of the stability and optoelectronic characteristics of molybdenum disulfide thin-film transistors by applying a nitrocellulose passivation layer

“…In this research, a novel nitrocellulose passivation layer is suggested for improving the stability of MoS 2 TFTs. Nitrocellulose is an organic material conventionally used as a bandage to protect wounds on the skin, as a lacquer, as nail polish, and as a material for protecting other materials due to its high waterproof characteristic, high flexibility, and biocompatibility [12]. Unlike the previous studies, the proposed passivation layer does not need vacuum equipment, high-temperature deposition, and a complex fabrication process.…”