A self-powered intracardiac pacemaker in swine model.

Harvesting biomechanical energy from cardiac motion is an attractive power source for implantable bioelectronic devices. Here, we report a battery-free, transcatheter, self-powered intracardiac pacemaker based on the coupled effect of triboelectrification and electrostatic induction for the treatment of arrhythmia in large animal models. We show that the capsule-shaped device (1.75 g, 1.52 cc) can be integrated with a delivery catheter for implanting in the right ventricle of a swine through the intravenous route, which effectively converts cardiac motion energy to electricity and maintains endocardial pacing function during the three-week follow-up period. We measure in vivo open circuit voltage and short circuit current of the self-powered intracardiac pacemaker of about 6.0 V and 0.2 µA, respectively. This approach exhibits up-to-date progress in self-powered medical devices and it may overcome the inherent energy shortcomings of implantable pacemakers and other bioelectronic devices for therapy and sensing.

Direct Mapping of Cytomechanical Homeostasis Destruction in Osteoarthritis Based on Silicon Nanopillar Array.

Osteoarthritis (OA) is the most prevalent joint degenerative disease characterized by chronic joint inflammation. The pathogenesis of OA has not been fully elucidated yet. Cartilage erosion is the most significant pathological feature in OA, which is considered the result of cytomechanical homeostasis destruction. The cytomechanical homeostasis is maintained by the dynamic interaction between cells and the extracellular matrix, which can be reflected by cell traction force (CTF). It is critical to assess the CTF to provide a deeper understanding of the cytomechanical homeostasis destruction and progression in OA. In this study, a silicon nanopillar array (Si-NP) with high spatial resolution and aspect ratio is fabricated to investigate the CTF in response to OA. It is discovered that the CTF is degraded in OA, which is attributed to the F-actin reorganization induced by the activation of RhoA/ROCK signaling pathway. Si-NP also shows promising potential as a mechanopharmacological assessment platform for OA drug screening and evaluation.

Reshaping the Endogenous Electric Field to Boost Wound Repair via Electrogenerative Dressing.

The endogenous electric field (EF) generated by transepithelial potential difference plays a decisive role in wound reepithelialization. For patients with large or chronic wounds, negative-pressure wound therapy (NPWT) is the most effective clinical method in inflammation control by continuously removing the necrotic tissues or infected substances, thus creating a proproliferative microenvironment beneficial for wound reepithelialization. However, continuous negative-pressure drainage causes electrolyte loss and weakens the endogenous EF, which in turn hinders wound reepithelialization. Here, an electrogenerative dressing (EGD) is developed by integrating triboelectric nanogenerators with NPWT. By converting the negative-pressure-induced mechanical deformation into electricity, EGD produces a stable and high-safety EF that can trigger a robust epithelial electrotactic response and drive the macrophages toward a reparative M2 phenotype in vitro. Translational medicine studies confirm that EGD completely reshapes the wound EF weakened by NPWT, and promotes wound closure by facilitating an earlier transition of inflammation/proliferation and guiding epithelial migration and proliferation to accelerate reepithelialization. Long-term EGD therapy remarkably advances tissue remodeling with mature epithelium, orderly extracellular matrix, and less scar formation. Compared with the golden standard of NPWT, EGD orchestrates all the essential wound stages in a noninvasive manner, presenting an excellent prospect in clinical wound therapy.

Improved pharmacodynamics of epidermal growth factor via microneedles-based self-powered transcutaneous electrical stimulation.

Epidermal growth factor is an excellent drug for promoting wound healing; however, its conventional administration strategies are associated with pharmacodynamic challenges, such as low transdermal permeability, reduction, and receptor desensitization. Here, we develop a microneedle-based self-powered transcutaneous electrical stimulation system (mn-STESS) by integrating a sliding free-standing triboelectric nanogenerator with a microneedle patch to achieve improved epidermal growth factor pharmacodynamics. We show that the mn-STESS facilitates drug penetration and utilization by using microneedles to pierce the stratum corneum. More importantly, we find that it converts the mechanical energy of finger sliding into electricity and mediates transcutaneous electrical stimulation through microneedles. We demonstrate that the electrical stimulation applied by mn-STESS acts as an "adjuvant" that suppresses the reduction of epidermal growth factor by glutathione and upregulates its receptor expression in keratinocyte cells, successfully compensating for receptor desensitization. Collectively, this work highlights the promise of self-powered electrical adjuvants in improving drug pharmacodynamics, creating combinatorial therapeutic strategies for traditional drugs.

Localized Myocardial Anti-Inflammatory Effects of Temperature-Sensitive Budesonide Nanoparticles during Radiofrequency Catheter Ablation.

Radiofrequency (RF) catheter ablation has emerged as an effective alternative for the treatment of atrial fibrillation (AF), but ablation lesions will result in swelling and hematoma of local surrounding tissue, triggering inflammatory cell infiltration and increased release of inflammatory cytokines. Some studies have shown that the inflammatory response may be related to the early occurrence of AF. The most direct way to inhibit perioperative inflammation is to use anti-inflammatory drugs such as glucocorticoids. Here, we prepared polylactic-co-glycolic acid (PLGA) nanoparticles loaded with budesonide (BUD) and delivered them through irrigation of saline during the onset of ablation. Local high temperature promoted local rupture of PLGA nanoparticles, releasing BUD, and produced a timely and effective local myocardial anti-inflammatory effect, resulting in the reduction of acute hematoma and inflammatory cell infiltration and the enhancement of ablation effect. Nanoparticles would also infiltrate into the local myocardium and gradually release BUD ingredients to produce a continuous anti-inflammatory effect in the next few days. This resulted in a decrease in the level of inflammatory cytokine IL-6 and an increase of anti-inflammatory cytokine IL-10. This study explored an extraordinary drug delivery strategy to reduce ablation-related inflammation, which may prevent early recurrence of AF.

Self-Powered Gesture Recognition Wristband Enabled by Machine Learning for Full Keyboard and Multicommand Input.

Virtual reality is a brand-new technology that can be applied extensively. To realize virtual reality, certain types of human-computer interaction equipment are necessary. Existing virtual reality technologies often rely on cameras, data gloves, game pads, and other equipment. These equipment are either bulky, inconvenient to carry and use, or expensive to popularize. Therefore, the development of a convenient and low-cost high-precision human-computer interaction device can contribute positively to the development of virtual reality technology. In this study, a gesture recognition wristband that can realize a full keyboard and multicommand input is developed. The wristband is convenient to wear, low in cost, and does not affect other daily operations of the hand. This wristband is based on physiological anatomy as well as aided by active sensor and machine learning technology; it can achieve a maximum accuracy of 92.6% in recognizing 26 letters. This wristband offers broad application prospects in the fields of gesture command recognition, assistive devices for the disabled, and wearable electronics.

An Ultra-Simple Charge Supplementary Strategy for High Performance Rotary Triboelectric Nanogenerators.

Free-standing rotary triboelectric nanogenerators (rTENG) can accomplish special tasks which require both high voltage and high frequency. However, the reported high performance rTENG all have complex structures for output enhancement. In this work, an ultra-simple strategy to build high performance rTENG is developed. With only one small paper strip added to the conventional structure, the output of the TENG is promoted hugely. The voltage is triplicated to 2.3 kV, and the current and charge are quintupled to 133 µA and 197 nC, respectively. The small paper strip, with the merits of ultra-simplicity, wide availability, easy accessibility and low cost, functions as a super-effective charge supplement. This simple and delicate structure enables ultra-high durability with the 2.3 kV voltage output 100% maintained after 1 000 000 cycles. This charge supplementary strategy is universally effective for many other materials, and decouples the output enhancement from any friction or contact on the metal electrodes, emphasizing a critical working principle for the rTENG. Atmospheric cold plasma is generated using the paper strip rTENG (ps-rTENG), which demonstrates strong ability to do bacteria sterilization. This simple and persistent charge supplementary strategy can be easily adopted by other designs to promote the output even further.

Accelerated Skin Wound Healing by Electrical Stimulation.

When the integrity of the skin got damaged, an endogenous electric field will be generated in the wound and a series of physiological reactions will be initiated to close the wound. The existence of the endogenous electric field of the wound has a promoting effect on all stages of wound healing. For wounds that cannot heal on their own, the exogenous electric field can assist the treatment. In this review, the effects of exogenous electrical stimulation on wound healing, such as the inflammation phase, blood flow, cell proliferation and migration, and the wound scarring is overviewed. This article also reviews the new electrical stimulation methods that have emerged in recent years, such as small power supplies, nanogenerators (NGs), and other physical, chemical or biological strategies. These new electrical stimulation methods and devices are safe, low-cost, stable, and small in size. The challenge and perspective are discussed for the future trends of the electrical stimulation treatment in accelerating skin wound healing.

A Stretchable, Self-Healable Triboelectric Nanogenerator as Electronic Skin for Energy Harvesting and Tactile Sensing.

Electronic skin that is deformable, self-healable, and self-powered has high competitiveness for next-generation energy/sense/robotic applications. Herein, we fabricated a stretchable, self-healable triboelectric nanogenerator (SH-TENG) as electronic skin for energy harvesting and tactile sensing. The elongation of SH-TENG can achieve 800% (uniaxial strain) and the SH-TENG can self-heal within 2.5 min. The SH-TENG is based on the single-electrode mode, which is constructed from ion hydrogels with an area of 2 cm × 3 cm, the output of short-circuit transferred charge (Qsc), open-circuit voltage (Voc), and short-circuit current (Isc) reaches ~6 nC, ~22 V, and ~400 nA, and the corresponding output power density is ~2.9 µW × cm-2 when the matching resistance was ~140 MΩ. As a biomechanical energy harvesting device, the SH-TENG also can drive red light-emitting diodes (LEDs) bulbs. Meanwhile, SH-TENG has shown good sensitivity to low-frequency human touch and can be used as an artificial electronic skin for touch/pressure sensing. This work provides a suitable candidate for the material selection of the hydrogel-based self-powered electronic skin.