An on-demand bioresorbable neurostimulator.

Bioresorbable bioelectronics, with their natural degradation properties, hold significant potential to eliminate the need for surgical removal. Despite notable achievements, two major challenges hinder their practical application in medical settings. First, they necessitate sustainable energy solutions with biodegradable components via biosafe powering mechanisms. More importantly, reliability in their function is undermined by unpredictable device lifetimes due to the complex polymer degradation kinetics. Here, we propose an on-demand bioresorbable neurostimulator to address these issues, thus allowing for clinical operations to be manipulated using biosafe ultrasound sources. Our ultrasound-mediated transient mechanism enables (1) electrical stimulation through transcutaneous ultrasound-driven triboelectricity and (2) rapid device elimination using high-intensity ultrasound without adverse health effects. Furthermore, we perform neurophysiological analyses to show that our neurostimulator provides therapeutic benefits for both compression peripheral nerve injury and hereditary peripheral neuropathy. We anticipate that the on-demand bioresorbable neurostimulator will prove useful in the development of medical implants to treat peripheral neuropathy.

Advances in Bioresorbable Triboelectric Nanogenerators.

With the growing demand for next-generation health care, the integration of electronic components into implantable medical devices (IMDs) has become a vital factor in achieving sophisticated healthcare functionalities such as electrophysiological monitoring and electroceuticals worldwide. However, these devices confront technological challenges concerning a noninvasive power supply and biosafe device removal. Addressing these challenges is crucial to ensure continuous operation and patient comfort and minimize the physical and economic burden on the patient and the healthcare system. This Review highlights the promising capabilities of bioresorbable triboelectric nanogenerators (B-TENGs) as temporary self-clearing power sources and self-powered IMDs. First, we present an overview of and progress in bioresorbable triboelectric energy harvesting devices, focusing on their working principles, materials development, and biodegradation mechanisms. Next, we examine the current state of on-demand transient implants and their biomedical applications. Finally, we address the current challenges and future perspectives of B-TENGs, aimed at expanding their technological scope and developing innovative solutions. This Review discusses advancements in materials science, chemistry, and microfabrication that can advance the scope of energy solutions available for IMDs. These innovations can potentially change the current health paradigm, contribute to enhanced longevity, and reshape the healthcare landscape soon.

Ultrasound-Driven On-Demand Transient Triboelectric Nanogenerator for Subcutaneous Antibacterial Activity.

To prevent surgical site infection (SSI), which significantly increases the rate morbidity and mortality, eliminating microorganisms is prominent. Antimicrobial resistance is identified as a global health challenge. This work proposes a new strategy to eliminate microorganisms of deep tissue through electrical stimulation with an ultrasound (US)-driven implantable, biodegradable, and vibrant triboelectric nanogenerator (IBV-TENG). After a programmed lifetime, the IBV-TENG can be eliminated by provoking the on-demand device dissolution by controlling US intensity with no surgical removal of the device from the body. A voltage of ≈4 V and current of ≈22 µA generated from IBV-TENG under ultrasound in vitro, confirming inactivating ≈100% of Staphylococcus aureus and ≈99% of Escherichia coli. Furthermore, ex vivo results show that IBV-TENG implanted under porcine tissue successfully inactivates bacteria. This antibacterial technology is expected to be a countermeasure strategy against SSIs, increasing life expectancy and healthcare quality by preventing microorganisms of deep tissue.

Virus blocking textile for SARS-CoV-2 using human body triboelectric energy harvesting.

Effective mitigation technology to prevent the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is required before achieving population immunity through vaccines. Here we demonstrate a virus-blocking textile (VBT) that repulses SARS-CoV-2 by applying repulsive Coulomb force to respiratory particles, powered by human body triboelectric energy harvesting. We show that SARS-CoV-2 has negative charges, and a human body generates high output current of which peak-to-peak value reaches 259.6 µA at most, based on triboelectric effect. Thereby, the human body can sustainably power a VBT to have negative electrical potential, and the VBT highly blocks SARS-CoV-2 by repulsion. In an acrylic chamber study, we found that the VBT blocks SARS-CoV-2 by 99.95%, and SARS-CoV-2 in the VBT is 13-fold reduced. Our work provides technology that may prevent the spread of virus based on repulsive Coulomb force and triboelectric energy harvesting.

Ultrasound-mediated triboelectric nanogenerator for powering on-demand transient electronics.

On-demand transient electronics, technologies referring subsequent material disintegration under well-defined triggering events and programmed time lines, offer exceptional clinical experiences in diagnosis, treatment, and rehabilitation. Despite potential benefits, such as the elimination of surgical device removal and reduction of long-term inimical effects, their use is limited by the nontransient conventional power supplies. Here, we report an ultrasound-mediated transient triboelectric nanogenerator (TENG) where ultrasound determines energy generation and degradation period. Our findings on finite element method simulation show that porous structures of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) play an essential role in the triggering transient process of our device under high-intensity ultrasound. Besides, the addition of polyethylene glycol improves triboelectric output performance; the voltage output increased by 58.5%, from 2.625 to 4.160 V. We successfully demonstrate the tunable transient performances by ex vivo experiment using a porcine tissue. This study provides insight into practical use of implantable TENGs based on ultrasound-triggered transient material design.

Cylindrical Free-Standing Mode Triboelectric Generator for Suspension System in Vehicle.

The triboelectric generator (TEG) is a strong candidate for low-power sensors utilized in the Internet of Things (IoT) technology. Within IoT technologies, advanced driver assistance system (ADAS) technology is included within autonomous driving technology. Development of an energy source for sensors necessary for operation becomes an important issue, since a lot of sensors are embedded in vehicles and require more electrical energy. Although saving energy and enhancing energy efficiency is one of the most important issues, the application approach to harvesting wasted energy without compromising the reliability of existing mechanical systems is still in very early stages. Here, we report of a new type of TEG, a suspension-type free-standing mode TEG (STEG) inspired from a shock absorber in a suspension system. We discovered that the optimum width of electrode output voltage was 131.9 V and current was 0.060 µA/cm² in root mean square (RMS) value while the optimized output power was 4.90 µW/cm² at 66 MΩ. In addition, output power was found to be proportional to frictional force due to the contact area between two frictional surfaces. It was found that the STEG was made of perfluoroalkoxy film and showed good mechanical durability with no degradation of output performance after sliding 11,000 times. In addition, we successfully demonstrated charging a capacitor of 330 µF in 6 min.

Enhanced thermal properties of graphene oxide-incorporated polymeric microspheres.

Polystyrene (PS) microspheres coated with graphene oxide (GO) were prepared and the variation of their thermal properties according to the GO loading was examined. The GO content in the PS-GO nanocomposites was controlled by the GO dispersions at various concentrations. The GO was coated onto the surface of the PS microspheres through the strong ionic interaction between polyvinylpyrrolidone and the GO sheet. The thermal properties of the GO incorporated PS microspheres were affected by the GO, which disturbed the chain activity and exhibited effective heat shielding. It also delayed the permeation of oxygen and hindered the escape of volatile degradation products from the PS-GO nanocomposites. In addition, the thermal degradation temperature of the nanocomposites was increased above 15 degrees C and their T(g) was also increased above 4.0 degrees C. PS-GO exhibited higher thermal conductivity (0.173 W/mK) than that of pure PS (0.117 W/mK).