Recent Advances in Triboelectric Nanogenerators: From Technological Progress to Commercial Applications.

Serious climate changes and energy-related environmental problems are currently critical issues in the world. In order to reduce carbon emissions and save our environment, renewable energy harvesting technologies will serve as a key solution in the near future. Among them, triboelectric nanogenerators (TENGs), which is one of the most promising mechanical energy harvesters by means of contact electrification phenomenon, are explosively developing due to abundant wasting mechanical energy sources and a number of superior advantages in a wide availability and selection of materials, relatively simple device configurations, and low-cost processing. Significant experimental and theoretical efforts have been achieved toward understanding fundamental behaviors and a wide range of demonstrations since its report in 2012. As a result, considerable technological advancement has been exhibited and it advances the timeline of achievement in the proposed roadmap. Now, the technology has reached the stage of prototype development with verification of performance beyond the lab scale environment toward its commercialization. In this review, distinguished authors in the world worked together to summarize the state of the art in theory, materials, devices, systems, circuits, and applications in TENG fields. The great research achievements of researchers in this field around the world over the past decade are expected to play a major role in coming to fruition of unexpectedly accelerated technological advances over the next decade.

Control of the Biodegradability of Piezoelectric Peptide Nanotubes Integrated with Hydrophobic Porphyrin.

Diphenylalanine (FF) is a piezoelectric material that is widely known for its high piezoelectric constant, self-assembly characteristics, and ease of manufacture. Because of its biocompatible nature, it is useful for implantable applications. However, its use in real applications is challenging because it degrades too easily in the body due to its solubility in water (0.76 g/mL). Upon incorporation of hydrophobic and biocompatible porphyrins into the FF, the degradability of the piezoelectric FF and their piezoelectric nanogenerators (PENGs) is controlled. Porphyrin-incorporated FFs are also formed as piezoelectric nanostructures well aligned on the substrate through self-assembly, and their piezoelectric properties are comparable to those of FF. The FF-based PENG degrades in only 5 min, whereas the FF-porphyrin-based PENG produces a stable output for >15 min in phosphate-buffered saline. This strategy for realizing biodegradable functional materials and devices with tunable degradation rates in the body can be applied to many implantable electronics.

Plasticized PVC-Gel Single Layer-Based Stretchable Triboelectric Nanogenerator for Harvesting Mechanical Energy and Tactile Sensing.

Triboelectric nanogenerators have garnered significant attention as alternative power sources for wearable electronics owing to their simple structure, easy fabrication, low cost, and superior power output. In this study, a transparent, stretchable, and attachable triboelectric nanogenerator (TENG) is built with an advanced power output using plasticized polyvinyl chloride (PVC)-gel. The PVC-gel exhibit very high negative triboelectric properties and electrically insulating PVC became an electrically active material. It is found that a single layer of PVC-gel can act as a dielectric and as a conducting layer. The PVC-gel based single layer of triboelectric nanogenerator (S-TENG) creates output signals of 24.7 V and 0.83 µA, i.e., a 20-fold enhancement in the output power compared to pristine PVC-based TENGs. In addition, the S-TENG can stably generate output voltage and current under stretching condition (80%). The S-TENG can be implemented as a tactile sensor that can sense position and pressure without combining multiple elements or electrode grid patterns. This study provides new applications of power sources and tactile sensors in wearable electronics.

The impact of dysphagia on quality of life in stroke patients.

The objective of this study was to investigate the quality of life in stroke patients using a swallowing quality of life (SWAL-QOL) questionnaire. The correlation between SWAL-QOL questionnaire outcome and videofluoroscopic dysphagia scale (VDS) scores in stroke patients was also determined.This cross-sectional study was retrospectively conducted with 75 stroke patients with dysphagia symptoms. Videofluoroscopic swallowing study (VFSS) and SWAL-QOL questionnaires were performed for all patients. These patients were divided into an oral feeding group and a tube feeding group. SWAL-QOL scores were compared between the 2 groups. The severity of dysphagia was estimated by VDS scores according to the videofluoroscopic swallowing study results. The relationships between SWAL-QOL scores and VDS scores were also investigated.The composite score was 48.82 ±â€Š19.51 for the tube feeding group and 53.17 ±â€Š25.42 for the oral feeding group. There were significant differences in burden and sleep subdomains of the SWAL-QOL between the 2 groups (P = .005 and P = .012, respectively). There was a significant negative correlation between the composite score of SWAL-QOL outcome and the total VDS score (r = -0.468, P = .012). The pharyngeal-phase score of the VDS had significant negative correlations with the SWAL-QOL subdomains of burden (r = -0.327, P = .013), mental health (r = -0.348, P = .008), and social functioning (r = -0.365, P = .029).To improve the quality of life of stroke patients, dysphagia rehabilitation should focus on the pharyngeal phase of dysphagia.