Biocompatible Lactulose-Based Resistive Random Access Memory for Implantable Electronics

Bioimplantable memory devices for digital healthcare must satisfy various requirements, such as biocompatibility and biostability. In this study, a biocompatible and biostable resistive random-access memory (RRAM) based on lactulose was developed as a bioimplantable memory device. Lactulose is a nonabsorbable disaccharide that includes multiple hydroxyl groups (-OH). To improve the durability of the RRAM, lactulose, which is biocompatible and does not decompose easily in the human body, was selected as the switching-layer material. The fabricated lactulose-based RRAM demonstrated stable bipolar resistive switching characteristics with a switching window of approximately 10³. In addition, a native MgO_x layer between the Mg top electrode and lactulose switching layer, which is attributed to bipolar resistive switching, was observed in the lactulose-based RRAM. Endurance and retention tests were conducted to confirm the stability of the device and its data storage properties. High uniformity and stability were also observed when the lactulose-based RRAM was built as a 6 × 6 crossbar array. Furthermore, an in vitro cell cytotoxicity test confirmed the feasibility for bioimplantable electronics of the fabricated lactulose-based RRAM, which shows a relative cell viability of 80.2% after 72 h of cell culture. Therefore, the lactulose-based RRAM can be used in bioimplantable electronics based on its bipolar resistive switching properties, stability, and data storage performance.