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.

An Ultrasound-Driven Bioadhesive Triboelectric Nanogenerator for Instant Wound Sealing and Electrically Accelerated Healing in Emergencies.

A bioadhesive triboelectric nanogenerator (BA-TENG), as a first-aid rescue for instant and robust wound sealing and ultrasound-driven accelerated wound healing, is designed. This BA-TENG is fabricated with biocompatible materials, and integrates a flexible TENG as the top layer and bioadhesive as the bottom layer, resulting in effective electricity supply and strong sutureless sealing capability on wet tissues. When driven by ultrasound, the BA-TENG can produce a stable voltage of 1.50 V and current of 24.20 µA underwater. The ex vivo porcine colon organ models show that the BA-TENG seals defects instantly (≈5 s) with high interfacial toughness (≈150 J m-2 ), while the rat bleeding liver incision model confirms that the BA-TENG performs rapid wound closure and hemostasis, reducing the blood loss by about 82%. When applied in living rats, the BA-TENG not only seals skin injuries immediately but also produces a strong electric field (E-field) of about 0.86 kV m-1 stimulated by ultrasound to accelerate skin wound healing significantly. The in vitro studies confirm that these effects are attributed to the E-field-accelerated cell migration and proliferation. In addition, these TENG adhesives can be applied to not only wound treatment, nerve stimulation and regeneration, and charging batteries in implanted devices.

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.

Droplet evaporation on porous fabric materials.

Droplet evaporation on porous materials is a complex dynamic that occurs with spontaneous liquid imbibition through pores by capillary action. Here, we explore water dynamics on a porous fabric substrate with in-situ observations of X-ray and optical imaging techniques. We show how spreading and wicking lead to water imbibition through a porous substrate, enhancing the wetted surface area and consequently promoting evaporation. These sequential dynamics offer a framework to understand the alterations in the evaporation due to porosity for the particular case of fabric materials and a clue of how face masks interact with respiratory droplets.