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Raindrop contains a large amount of renewable mechanical energy. Acid rain has adverse impact on the plants, aquatic animals and infrastructure. In this work, a triboelectric raindrop generator (TRG) was developed to harvest raindrop energy on a large scale. The TRG consists of electrification layer, electrodes and substrate. At the rainfall rate of 53 mL/s, the open‐circuit voltage and short‐circuit currents of the device reaches 27 V and 4.6 μA, respectively, which can simultaneously drive 60 LED light‐emitting diodes or charge a 5 μF capacitor. In addition, relied on the electrostatic shielding effect of the solid–liquid interface, the pH value of ambient solution drops can be spontaneously detected to reveal the potential in real‐time monitoring of environmental quality. By integrating with a signal processing circuit, a self‐powered acid rain alert system was formed for real‐time monitoring the acidity of the falling raindrops. This work proposes a feasible and innovative approach for active environmental monitoring.

Due to the extensive energy consumption and high population density in modern cities, the collection and use of scattered walking energy from the stream of people is crucial for the development of a green ecological city. Herein, a flexible undulated electrode-based triboelectric nanogenerator (u-TENG) was integrated to the floor to scavenge walking energy from pedestrians, promoting the ordered collection of disordered and scattered energy. Driven by the steps of human walking, the output of the as-fabricated u-TENG are an open-circuit voltage of 86 V and a short-circuit current of 6.2 μA, which are able to continuously light up 110 light-emitting diode bulbs. In addition, a self-powered location-tracking system was prepared for pedestrian volume counting and passenger tracing with the purpose of reducing energy consumption in public areas. The proposed walking energy harvesting device is flexible, feasible, and unaffected by season, climate, or location. This work not only proposes a strategy for mechanical energy harvesting in public areas, including subway stations, hospitals, shopping malls, and business streets, but also offers a novel solution for smart cities and low-carbon transportation alternatives.

In mammals, physiological respiration involves respiratory cycles of inhaled and exhaled breaths, which has traditionally been an underutilized resource potentially encompassing a wealth of physiologically relevant information as well as clues to potential diseases. Recently, triboelectric nanogenerators (TENGs) have been widely adopted for self-powered respiration monitoring owing to their compelling features, such as decent biocompatibility, wearing comfort, low-cost, and high sensitivity to respiration activities in the aspect of low frequency and slight amplitude body motions. Physiological respiration behaviors and exhaled chemical regents can be precisely and continuously monitored by TENG-based respiration sensors for personalized health care. This article presents an overview of TENG enabled self-powered respiration monitoring, with a focus on the working principle, sensing materials, functional structures, and related applications in both physical respiration motion detection and chemical breath analysis. Concepts and approaches for acquisition of physical information associated with respiratory rate and depth are covered in the first part. Then the sensing mechanism, theoretical modeling, and applications related to detection of chemicals released from breathing gases are systemically summarized. Finally, the opportunities and challenges of triboelectric effect enabled self-powered respiration monitoring are comprehensively discussed and criticized.

Function location type, category, model, manufacturer, equipment parameter, defect information and operation/maintenance information are key fields of electrical power system equipment account data, which are organized with account data ID as the main keyword. In the past, there was a lack of mining methods and a large amount of account data was not analyzed. In this paper, a standardized technique for computer implementation is proposed, which transforms any account data table into sparse adjacency matrix, and then transforms adjacency matrix into map. With the same functional location type in the account data map, according to the equipment model, manufacturer and technical parameters associated, the information of potential spare parts and the quality of account data can be got. With the same category and model, according to the function position type, defect appearance, defect reason and treatment measure field, family defects of equipment is got. According to the treatment measure field, the prevention and maintenance method for family defect of equipment can be formed.

Introduction Human respiration is rich in physiological and pathological information as biomarker for health assessment and illness prediction. Respiratory diagnosis method carries various advantages, such as continuity, non-invasiveness, comfort and user-friendly [6]. Typically, ammonia (NH3) in exhaled breath can be served as biomarker for some diseases like end-stage renal disease (ESRD), ulcers caused by Helicobacter pylori or bacterial in oral cavity [12-15]. NH3 concentration in healthy people’ exhaled breath is about 0.425-1.8 ppm (mean 0.96 ppm), while the one in ESRD patients’ breathing ranges from 0.82 to14.7 ppm (mean 4.88 ppm) [12]. Even though various traditional sensors have been applied to monitor human physiological information like heartbeat or respiration, some limitations, such as bulky structure, poor portability and requirement of external power sources remarkably restricted their widespread application in smart mobile medical electronics [16]. Therefore, a self-powered ammonia sensor that can harvest energy from human body is desperately needed. In addition, it is underexplored but will be a novel and superior solution if a wearable sensor that could simultaneously chemically detect the inhalation and measure the breath rate for respiration analysis without a power supply. Device fabrication The as-developed triboelectric self-powered respiration sensor (TSRS) is composed of Ce-doped ZnO, Polydimethylsiloxane (PDMS), Au foils and PET films, as revealed in Fig. 1a. Ce-doped ZnO plays dual roles of gas sensing material and triboelectrification layer (Fig. 1b). PDMS functions as the triboelectric layer and Au foils were coated on the back of both triboelectric layers as electrodes. To improve the flexibility and air tightness, the whole device was packed with soft silica gel films. The patterned PDMS film exhibits good transparency and flexibility, as shown in Fig. 1c and 1d. Figure 1e sketches the fabrication flow of the TSRS. Driven by the continuous expansion and contraction of the chest during respiration (Fig. 1g), the deformation of TSRS inflated can be converted into electric signals and human exhaled gas can flow into the TSRS through a soft tube with the breathing process, enabling the real-time spontaneous monitoring of both respiratory behaviors and exhaled gas. Method To explore the sensing behavior of as-prepared TSRS toward NH3 from 0.1 to 10 ppm, including the trace level region (region Ⅰ, 0.1 to 1 ppm) and micro level region (region Ⅱ, 2 to 10 ppm), the NH3-sensing response-concentration fitting curves are plotted in Fig. 2a for five samples. It is found that without moisture atmosphere, the TSRS exhibits an opposite sensing behavior and the response declines with increasing ammonia concentration in both region Ⅰ (Fig. 2e) and region Ⅱ (Fig. 2f). A steeper slope is observed under humid NH3 atmosphere in comparison with the dry NH3 atmosphere, indicating that the existence of water molecular will raise the sensing performance. As a consequence, the moisture-resistant feature of the as-developed TSRS favours NH3 detection in human exhaled gas. Figure 2g elucidates dynamic response profile of TSRS when exposed to 0.01 ppm NH3 with 97.5%RH, which indicates that the TSRS is sensitive to NH3 as low as 0.01 ppm and the response time is nearly 155 s. Results and Conclusions Attached on the human chest, the as-prepared TSRS delivers a stable output voltage signal within 5 min normal breathing (Fig. 3a). The wearable sensor can be applied to distinguish different types of breathing behaviors and human respiratory states after physical exercise. Figure 3b presents the real-time output recording of diverse breathing behaviors, including normal breathing, deep breathing, shallow breathing and rapid breathing. Human respiration rate and depth can be clearly recognized in terms of frequency and amplitude of the output voltage signals. The deep breathing pattern has a bigger peak-to-peak amplitude and wider interval than normal breathing pattern due to the larger and slower change in chest circumference. In addition, the physiological process of human body after exercise can also be accurately reflected by breathing intensity and frequence. The breathing amplitude after 100 squats is more intense than that after 50 squats, as displayed in Fig. 3c. Meanwhile, the injection of exhaled NH3 gas into the TSRS apparently enlarges the amplitude of the output voltage (Fig. 3d), revealing the capability of simultaneously detecting breathing behaviors and exhaled gases. References [1] M. Righettoni, A. Amann, S.E. Pratsinis, Breath analysis by nanostructured metal oxides as chemo-resistive gas sensors, Materials Today. 18 (2015) 163–171. doi:10.1016/j.mattod.2014.08.017 [2] P. Le Maout, J.L. Wojkiewicz, N. Redon, C. Lahuec, F. Seguin, L. Dupont, , Polyaniline nanocomposites based sensor array for breath ammonia analysis. Portable e-nose approach to non-invasive diagnosis of chronic kidney disease, Sens. Actuators, B Chem. 274 (2018) 616 –626. doi:10.1016/j.snb.2018.07.178 [3] S. Wang, H. Tai, B. Liu, Z. Duan, Z. Yuan, H. Pan, Y. Su, G. Xie, X. Du, Y. Jiang, A Facile Respiration-Driven Triboelectric Nanogenerator for Multifunctional Respiratory Monitoring, Nano Energy. 58 (2019) 312–321. doi:10.1016/j.nanoen.2019.01.042 [4] Y. Jung, H.G. Moon, C. Lim, K. Choi, H.S. Song, S. Bae, S.M. Kim, M. Seo, T. Lee, S. Lee, H.H. Park, S.C. Jun, C.Y. Kang, C. Kim, Humidity-Tolerant Single-Stranded DNA-Functionalized Graphene Probe for Medical Applications of Exhaled Breath Analysis, Advanced Functional Materials. 27 (2017) 1–9. doi:10.1002/adfm.201700068 Figure 1

Introduction Nitrogen dioxide (NO2) is a ubiquitous hazardous gas species that can cause light pollution, acid rain [1-3], and water pollution [4]. With increasing vehicles ownership and emission, exhaust from automobiles, i.e. nitrogen dioxide (NO2) and its derivatives, imposes huge threaten on the air quality and public health. However, a majority of the gas sensors demand additional energy supply and undoubtedly increase the energy consumption of the whole device, inhibiting the portability and mobility of the device. A bionic alveolus-shaped triboelectric gas sensor (ATGS) has been designed and fabricated for spontaneously NO2 detection at room temperature. Furthermore, a sensing modeling was proposed by combining the thermodynamic analysis and finite element calculation together with phase-field simulation. This work not only provides a facile, low-cost and portable approach for active gas sensing and real-time physiological assessment, but also proposes a theoretical modeling for self-powered gas detection. Device fabrication The configuration of ATGS is based on contact-separate mode Triboelectric Nanogenerator (TENG). A layer of acrylic with the dimension of 40mm×40mm×1mm was tailored by laser etching machine, together with a layer of latex with the dimension of 40mm×40mm×0.2mm was cleaned by ethanol and deionized water. Then copper electrode with a thickness of 200nm was coated on the one side of the tailored acrylic sheet by thermal evaporation, followed by deposition of prepared suspensions as the gas sensitive material via gas spraying. Subsequently, the WO3/copper coated acrylic sheet was etched through laser etching machine to create a central hole with diameter of 4.0 mm. Then, the latex layer was attached to WO3/copper coated acrylic sheet to form the gas test chamber. Epoxy resin was used to seal the edges between latex film and acrylic sheet to ensure the gas tightness. A plastic tube was integrated as the inlet and outlet of the target gas into the sensor. Method The internal combustion engines burning fossil fuels generate and release huge amount of nitrogen dioxide, which is large threat to environment and public health, as shown in Figure 1a. To address the concern, we designed an alveolus-shaped triboelectric gas sensor (ATGS) for both nitrogen dioxide detection and personal breath behavior monitoring, as the configuration shown in Figure 1b. It was vertically laminated with latex, sensitive material, copper electrode and a plastic air conduit serving as the gas conducting channel. Here, latex film is selected as the contacting layer for its good stretchability and strong electron affinity. Figure 1c shows the photograph of the as-fabricated AIMS, where the gas inflation will hold up the latex membrane to form a tent while the deflation will shrink the tent. During this processing, the latex forms a cycle of contact and separation with the bottom substrate material, pumping the electrons to flow back and forth between the copper electrode and the ground. The working principle and finite element calculation of the as-prepared AIMS is elucidated in Fig. 1d and 1f. Results and Conclusions To explore the gas sensing capability of the as-fabricated ATGS, the output voltage versus NO2 gas concentrations from 0 ppm to 100 ppm were investigated. Compared with 0.01 g and 0.1 g alkali treatments, the device with 0.02 g NaOH treatment revealed a much better sensitivity and linearity, as shown in Fig. 2a, where a response of 452.44% was achieved when being exposed to 100 ppm NO2. In addition, as presented in Fig. 2b, a linearity of 0.976 is observed for the AIMS with 0.02 g NaOH treatment, demonstrating its capability of actively detecting nitrogen dioxide in a wide concentration range. The ATGS also demonstrated capability in distinguishing diverse breathing patterns without any power supply (Fig. 2c). In addition, the NO2 response is at least 20 times higher than other gases, implying a good selectivity (Fig. 2d) A phase-field simulation and finite element calculation were implemented to numerically verify the permittivity effect on the electric field and polarization of sensitive film. As shown in Fig. 3k, the polarization increases with increasing relative dielectric constant, while the electric field follows an opposite trend. Given the depolarization field is proportional to the polarization once the device is fixed, the increase of permittivity facilitates the depolarization of the sensitive layer, which is in agreement with the aforementioned theoretical derivation and experimental data. References [1] R. Ehrlich, M.C. Henry, Chronic toxicity of nitrogen dioxide. I. Effect on resistance to bacterial pneumonia, Journal of Occupational Medicine. 12 (1970) 34. doi: 10.1080/00039896.1968.10665342. [2] K. Mukala, J. Pekkanen, P. Tiittanen, S. Alm, R. Salonen, J. Tuomisto, Personally measured weekly exposure to NO2 and respiratory health among preschool children, European Respiratory Journal 13 (1999) 1411-1417. doi:10.1183/09 031936.99.13614189 [3] R.L. Tse, A.A. Bockman, Nitrogen dioxide toxicity report of four cases in firemen, J. Am. Med. Assoc 212 (1970) 1341-1344. doi: 10.1001/jama.212.8.1341. [4] G. Sberveglieri, P. Benussi, G. Coccoli, S. Groppelli, P. Nelli, Reactively sputtered indium tin oxide polycrystalline thin films as NO and NO2 gas sensors, Thin Solid Films 186 (1990) 349–360. doi:10.1016/0040-6090(90)90150-C. Figure 1

Increasing light absorption is of crucial importance for optimizing light-activated gas detection. However, the relevant research is still far from sufficient. Herein, a high performance visible light-activated NO2 gas sensor is developed relied on the localized surface plasmon resonance (LSPR) and increased surface oxygen vacancies. Au NPs decorated ZnO nanorod array as sensitive materials was synthesized via a two-step low temperature hydrothermal process. The influences of Au decoration and light wavelength on the sensing behaviors were systematically investigated. It is found that the Au NPs decoration can largely promote the visible light-activated gas sensing properties in comparison with pure ZnO film. In addition, the as-prepared sensors demonstrate excellent repeatability and selectivity as well as moisture stability. Moreover, the sensing mechanism based on LSPR was discussed in detail. This work not only sheds some lights on the fundamental understanding for the LSPR enhanced gas sensing mechanism, but also offers an approach in constructing high-performance light-activated gas sensor.

Nitrogen dioxide sensors with high sensitivity and low energy consumption are demanded for atmosphere sensing networks. Here, a self-powered room temperature NO2 sensor has been developed based on the conjugation between the triboelectric and photoelectric effect. By converting the mechanical motions into electricity, a triboelectric nanogenerator (TENG) serves as a power source to simultaneously drive chemoresistive gas sensing and UV illumination. Under a 5 Hz external impact, the output voltage drop across interdigital electrodes has a proportional relationship with the NO2 concentration. A self-powered optomechatronic gas sensor (OGS) with hydrothermal ZnO nanowires synthesized at a concentration of 0.035 mol/l exhibits a superior response (∼14.8) and sensitivity (0.302 ppm−1) than those synthesized at other concentrations. Furthermore, the influence of the external force frequency and rectification on the gas sensing properties was systematically investigated. It is found that the TENG induced built-in electric field can effectively modulate the internal quantum efficiency and thus the sensing performance of OGSs. This work not only paves the way for constructing self-powered optomechatronic devices and systems but also pushes forward the active multifunctional network node for environmental monitoring.