No abstract

A high demand for green and eco-friendly triboelectric nanogenerators (TENGs) has multiplied the importance of their degradability for biomedical applications. However, the charge generation of current eco-friendly TENGs is generally limited. In this research, a flexible TENG based on a silk fibroin (SF) fibrous layer and a polycaprolactone (PCL)/graphene oxide (GO) fibrous layer was developed. Moreover, the PCL/GO layer was surface modified using various concentrations of GO (0, 1.5, 3, 6, and 9 wt%). We demonstrated that surface modification using GO nanosheets significantly improved the output of the TENG. Notably, the optimized GO modified layer resulted in a voltage of 100 V, a current of 3.15 mA m −2 , and a power density of 72 mWm −2 . Moreover, a thin PCL layer applied as an encapsulation layer did not significantly modulate the performance of the TENG. Furthermore, during 28 d of soaking in a phosphate buffer solution, the proposed TENG was able to successfully generate electricity. The TENG was also proposed to be used for the electrical stimulation of PC12 cells. The results confirmed that this self-powered electrical stimulator could promote the attachment and proliferation of PC12 cells. Therefore, we have shown the potential for an eco-friendly and cost-effective TENG based on GO modified PCl/GO and silk fibrous layers to be used as a power source for biomedical applications.

Over the last decade, in pursuit to provide suitable alternatives for power supplies of medical devices in regenerative medicine, extensive research on nanogenerators has been developed. Such devices can overcome current commercial battery challenges, including intense heat-on-body complications due to the electrical current during therapeutic usage, leading to protein denaturation, cell structure destruction, and even cell necrosis. In addition, these traditional batteries contain a bulky and heavy structure that prevents them from providing sustainable on body biomedical therapeutic intervention. Furthermore, advantages such as wide-range biocompatible and biodegradable materials, lightweight, and sufficient stretchability for device construction can minimize the side effects of implantable devices, including inflammation or toxicity, as well as eliminate secondary surgery to replace or remove batteries. Triboelectric nanogenerators (TENGs) are associated with harvesting mechanical energy in various forms, among which human body motions can serve as a renewable power source for healthcare systems. This review is written to emphasize the importance of TENG's applications in regenerative medicine and modulation purposes, particularly for the nervous system. Some crucial parameters for implantable consideration are discussed. In the concluding remarks, features for clinical utilization including output efficiency, encapsulation, stability, and miniaturization are suggested as challenges and prospects.

Human interaction with machines can be made easy, comfortable, and accessible by introducing user-friendly interfaces. In the case of wearable devices, their sensors and other interfacing elements are very well within the proximity of users. Since biopotential signals can be accessed from the surface of the human skin, users can have seamless interaction with wearable human-computer interactive devices. Rigid interfaces can hinder the user experience, and therefore, the need for soft biopotential interfaces is important. Imperceptible and unobtrusive soft biopotential interfaces will drastically enhance many aspects of human-computer interaction. This paper reviews the use of soft, flexible, and stretchable biopotential interfaces in wearable human-machine interactive devices. Additionally, attention is brought to the scope of other possible applications of soft biopotential interfaces in wearable devices.