Fabrication of Highly Dense Silk Fibroin Biomemristor Array and Its Resistive Switching Characteristics

Abstract

Development of polymeric memristors is of great interest for wearable and implantable applications because of its flexibility and transparency. One of distinguished polymeric memristor materials is silk fibroin, which is a biodegradable protein extracted from Bombyx mori cocoons. However, fibroin memristors demonstrated earlier show low memory cell density (<100 cells mm−2). In this paper, silk fibroin memristors with cell density 25 times higher than that of the previously reported silk fibroin memristors by utilizing wafer‐scale UV photolithography are reported. Unlike shadow masking technique adopted in the previous researches, UV photolithography allows single‐micrometer‐scale alignment between layers to obtain a much denser structure. Memristive characteristics of the silk fibroin memristors are studied under different values of compliance current during SET process with different thickness of silk fibroin films. The ON/OFF ratio of the fabricated memristors is maintained over 1000 s of measurement, and remains the same during bending over a cylinder with a radius of curvature of 1.3 mm. It is shown that silk fibroin remains biocompatible and biodegradable after undergoing the fabrication process. Demonstrated transparency and lightweight characteristics are desirable for electronic components for wearable and implantable systems.

New Silk Road: From Mesoscopic Reconstruction/Functionalization to Flexible Meso‐Electronics/Photonics Based on Cocoon Silk Materials

“…[116] Among the several types of memory devices, protein-based memristors exhibit typical resistive switching memory properties with other beneficial features such as biocompatibility, flexibility, and bio-resorbability, and have thus been applied in implantable electronic devices. [97,[118][119][120] Owing to the natural abundance and low cost, protein materials have emerged as excellent candidates for the development of bio-integrated electronic devices. [118] Recently, protein materials such as SF, egg albumen, keratin, ferritin, collagen, S-layer protein, and sericin have been developed for the construction of biodegradable and biocompatible memristors.…”

“…[133] After extensive research in recent years, SF has been proved to successfully achieve the typical resistive switching performance and can be fabricated as a memristor array, as well as, emulate both the synaptic structures and function, exhibiting significant potential in the nonvolatile random access memory applications. [97,120] However, most studies have utilized the inherent characteristics of SF materials such as solution processability, excellent biocompatibility, low weight, and controllable biodegradation, but development in terms of the mesoscopic structural modification has been lacking. Conventional protein-based memristors are restricted by the inherent disadvantages of protein materials under external electrical field, that is, random ion deposition and unstable structure, leading to low switching speed, high operating voltage, and inferior endurance property.…”

Flexible and Stretchable Memristive Arrays for in-Memory Computing

“…Organic materials often show better flexibility than inorganic materials, which are potential candidates for fabricating flexible memristive devices and arrays. Common organic materials, such as albumin (Chen et al, 2015), collagen (Zeng et al, 2019), silk fibroin (Kook et al, 2020;Wang et al, 2016a), polyethyleneimine (PEI) (Yang et al, 2020) and poly(1,3,5-trivinyl-1,3,5trimethylcyclotrisiloxane) (pV 3 D 3 ) (Jang et al, 2019;Jang J. et al, 2018a), have demonstrated their promising application in flexible memristive devices and arrays. By employing waferscale ultraviolet photolithography technology, a silk fibroin-based memristive array was successfully fabricated on a parylene-C film with robust flexibility (Kook et al, 2020).…”

“…Common organic materials, such as albumin (Chen et al, 2015), collagen (Zeng et al, 2019), silk fibroin (Kook et al, 2020;Wang et al, 2016a), polyethyleneimine (PEI) (Yang et al, 2020) and poly(1,3,5-trivinyl-1,3,5trimethylcyclotrisiloxane) (pV 3 D 3 ) (Jang et al, 2019;Jang J. et al, 2018a), have demonstrated their promising application in flexible memristive devices and arrays. By employing waferscale ultraviolet photolithography technology, a silk fibroin-based memristive array was successfully fabricated on a parylene-C film with robust flexibility (Kook et al, 2020). The fabricated memristive crossbar array shows robust flexibility (bendable to a radius of 1.3 mm) and reliable electrical performance (Figure 2D).…”

Intervention of Polydopamine Assembly and Adhesion on Nanoscale Interfaces: State‐of‐the‐Art Designs and Biomedical Applications

“…[54,55] The broadband monotonic absorption ranging from the ultraviolet (UV) to the near-infrared (NIR) region [56] and the movement of charge carriers through the -system in PDA would lead to strong photothermal conversion and photonto-current conversion ability by irradiating the materials with protons above the relevant optical gaps. [57][58][59][60][61] It is thus highly attractive to serve as endogenous photoacoustic contrast agent, photothermal conversion agent and photoelectric material. [62][63][64][65] Moreover, the -electron-rich interfaces in PDA make them pow-erful to bind with various electron-rich molecules viastacking and -cation interactions.…”