Highly transparent and flexible Ag nanowire-embedded silk fibroin electrodes for biocompatible flexible and transparent heater

Designing Silk Biomaterials toward Better Future Healthcare: The Development and Application of Silk-Based Implantable Electronic Devices in Clinical Diagnosis and Therapy

Implantable medical electronic devices (IMEDs) have attracted great attention and shown versatility for solving clinical problems ranging from real-time monitoring of physiological/ pathological states to electrical stimulation therapy and from monitoring brain cell activity to deep brain stimulation. The ongoing challenge is to select appropriate materials in target device configuration for biomedical applications. Currently, silk-based biomaterials have been developed for the design of diagnostic and therapeutic electronic devices due to their excellent properties and abundant active sites in the structure. Herein, the aim is to summarize the structural characteristics, physicochemical properties, and bioactivities of natural silk biomaterials as well as their derived materials, with a particular focus on the silk-based implantable biomedical electronic devices, such as implantable devices for invasive brain-computer interfaces, neural recording, and in vivo electrostimulation. In addition, future opportunities and challenges are also envisioned, hoping to spark the interests of researchers in interdisciplinary fields such as biomaterials, clinical medicine, and electronics.

Silk Fibroin Film Decorated with Ultralow FeCo Content by Sputtering Deposition Results in a Flexible and Robust Biomaterial for Magnetic Actuation

Magnetically responsive soft biomaterials are at the forefront of bioengineering and biorobotics. We have created a magnetic hybrid material by coupling silk fibroin─i.e., a natural biopolymer with an optimal combination of biocompatibility and mechanical robustness─with the FeCo alloy, the ferromagnetic material with the highest saturation magnetization. The material is in the form of a 6 μm-thick silk fibroin film, coated with a FeCo layer (nominal thickness: 10 nm) grown by magnetron sputtering deposition. The sputtering deposition technique is versatile and eco-friendly and proves effective for growing the magnetic layer on the biopolymer substrate, also allowing one to select the area to be decorated. The hybrid material is biocompatible, lightweight, flexible, robust, and water-resistant. Electrical, structural, mechanical, and magnetic characterization of the material, both as-prepared and after being soaked in water, have provided information on the adhesion between the silk fibroin substrate and the FeCo layer and on the state of internal mechanical stresses. The hybrid film exhibits a high magnetic bending response under a magnetic field gradient, thanks to an ultralow fraction of the FeCo component (less than 0.1 vol %, i.e., well below 1 wt %). This reduces the risk of adverse health effects and makes the material suitable for bioactuation applications.

A thin-film polymer heating element with a continuous silver nanowires network embedded inside

This study presents a method for fabricating a film-based heating element using a polymer material with an array of intersecting conductive elements embedded within it. Track-etched membranes (TM) with a thickness of 10μm were used as the template, and their pores were filled with metal, forming a three-dimensional grid. Due to the unique manufacturing process of TM, the pores inside intersect with each other, allowing for contacts between individual nanowires (NWs) when filled with metal. Experimental results demonstrated that filling the TM pores with silver allows for heating temperatures up to 78 degrees without deformation or damage to the heating element. The resulting flexible heating element can be utilized in medical devices for heating purposes or as a thermal barrier coating.

Highly flexible Ag nanowire network covered by a graphene oxide nanosheet for high-performance flexible electronics and anti-bacterial applications

We investigated a flexible and transparent conductive electrode (FTCE) based on Ag nanowires (AgNWs) and a graphene oxide (GO) nanosheet and fabricated through a simple and cost-effective spray coating method. The AgNWs/GO hybrid FTCE was optimized by adjusting the nozzle-to-substrate distance, spray speed, compressor pressure, and volume of the GO solution. The optimal AgNWs/GO hybrid FTCE has a high transmittance of 88% at a wavelength of 550 nm and a low sheet resistance of 20 Ohm/square. We demonstrate the presence of the GO nanosheet on the AgNWs through Raman spectroscopy. Using scanning electron microscopy and atomic force microscopy, we confirmed that the nanosheet acted as a conducting bridge between AgNWs and improved the surface morphology and roughness of the electrode. Effective coverage by the GO sheet improved the conductivity of the AgNWs electrode Effective coverage of the GO sheet improved conductivity of the AgNWs electrode with minimum degradation of optical and mechanical properties. Flexible thin film heater (TFH) and electroluminescent (EL) devices fabricated on AgNWs/GO hybrid FTCEs showed better performance than devices on bare AgNWs electrodes due to lower sheet resistance and uniform conductivity. In addition, an AgNWs/GO electrode layer on a facial mask acts as a self-heating and antibacterial coating. A facial mask with an AgNWs/GO electrode showed a bacteriostatic reduction rate of 99.7 against Staphylococcus aureus and Klebsiella pneumonia.