Ocean energy, in theory, is an enormous clean and renewable energy resource that can generate electric power much more than that required to power the entire globe without adding any pollution to the atmosphere. However, owing to a lack of effective technology, such blue energy is almost unexplored to meet the energy requirement of human society. In this work, a fully packaged hybrid nanogenerator consisting of a rolling triboelectric nanogenerator (R-TENG) and an electromagnetic generator (EMG) is developed to harvest water motion energy. The outstanding output performance of the R-TENG (45 cm3 in volume and 28.3 g in weight) in the low-frequency range (<1.8 Hz) complements the ineffective output of EMG (337 cm3 in volume and 311.8 g in weight) in the same range and thus enables the hybrid nanogenerator to deliver valuable outputs in a broad range of operation frequencies. Therefore, the hybrid nanogenerator can maximize the energy conversion efficiency and broaden the operating frequency simultaneously. In terms of charging capacitors, this hybrid nanogenerator provides not only high voltage and consistent charging from the TENG component but also fast charging speed from the EMG component. The practical application of the hybrid nanogenerator is also demonstrated to power light-emitting diodes by harvesting energy from stimulated tidal flow. The high robustness of the R-TENG is also validated based on the stable electrical output after continuous rolling motion. Therefore, the hybrid R-TENG and EMG device renders an effective and sustainable approach toward large-scale blue energy harvesting in a broad frequency range.
Conductive hydrogels as promising candidates of wearable electronics have attracted considerable interest in health monitoring, multifunctional electronic skins, and human-machine interfaces. However, to simultaneously achieve excellent electrical properties, superior stretchability, and a low detection threshold of conductive hydrogels remains an extreme challenge. Herein, an ultrastretchable high-conductivity MXene-based organohydrogel (M-OH) is developed for human health monitoring and machine-learning-assisted object recognition, which is fabricated based on a Ti3C2Tx MXene/lithium salt (LS)/poly(acrylamide) (PAM)/poly(vinyl alcohol) (PVA) hydrogel through a facile immersion strategy in a glycerol/water binary solvent. The fabricated M-OH demonstrates remarkable stretchability (2000%) and high conductivity (4.5 S/m) due to the strong interaction between MXene and the dual-network PVA/PAM hydrogel matrix and the incorporation between MXene and LS, respectively. Meanwhile, M-OH as a wearable sensor enables human health monitoring with high sensitivity and a low detection limit (12 Pa). Furthermore, based on pressure mapping image recognition technology, an 8 × 8 pixelated M-OH-based sensing array can accurately identify different objects with a high accuracy of 97.54% under the assistance of a deep learning neural network (DNN). This work demonstrates excellent comprehensive performances of the ultrastretchable high-conductive M-OH in health monitoring and object recognition, which would further explore extensive potential application prospects in personal healthcare, human-machine interfaces, and artificial intelligence.
Piezoelectric multilayers can achieve both piezoelectric and triboelectric generation simultaneously by the deformation and contacting–separating process between upper and lower surfaces of adjacent layers. The electrospun poly(vinylidene fluoride) (PVDF) fiber film as a type of piezoelectric multilayer with abundant inner surfaces can generate both large piezoelectric and triboelectric signals. However, in most studies on the piezoelectric fiber films, the high-generation performances are attributed to the piezoelectric properties and their triboelectric contribution is usually ignored. Thus, the contributions of triboelectricity in piezoelectric multilayers should be considered, and a highly effective hybrid nanogenerator needs to be designed by achieving the synergy of triboelectricity and piezoelectricity. Herein, a head-to-head parallel assembly was used in a PVDF multilayer generator to improve the electricity output, and the respective contributions and synergistic effect of triboelectricity and piezoelectricity in multilayer generators were studied. The maximum open-circuit voltage, short-circuit current, and charge values of the designed hybrid nanogenerator device were 150 V, 7 μA, and 100 nC, respectively. Then, the head-to-head parallel assembly method was used for electrospun poly(vinylidene fluoride-co-trifluoroethylene) fiber films, and the output performance was shown to be about 4 times that obtained by the normal series connection. This head-to-head parallel assembly can be used as a common harvesting method to collect piezoelectric and triboelectric energy effectively from piezoelectric multilayers.
This literature survey, conducted by the Digital Cellulose Center, details sensors and energy harvesting technologies capable of being integrated in, or on, cellulose-based materials such as paper or board. The goal of the survey is to identify how full sensor system integration can be performed on environmentally friendly substrates. Using cellulose and other bio-based materials from the forest is a promising way of making electronics greener. Also, such system integration can add new intelligence to existing cellulose products such as packages for food and logistics. The survey focuses on moisture sensors, temperature sensors, pressure and strain sensors, piezoelectric cellulose, patterning methods, and triboelectric nanogenerators, each one divided into separate chapters. The outcome of the survey is considered in the light of connected cellulose-based sensor applications, identifying the most pertinent scientific questions and remaining challenges. We particularly consider the results in light of sensors integrated into pressboard.
Abstract Low-cost, handily prepared, and efficient large-scale triboelectric nanogenerator (TENG) is considered as the new scheme for distributed mechanical conversion or renewable blue energy utilization. Semiconductors with high carrier mobility introduction potency overcome pure polymer restriction for uncompetitive short current density. An extremely popular all-inorganic lead-free double perovskite Cs 2 AgBiBr 6 (CABB) has emerged as extraordinary potential material in the substitution of semiconductor triboelectric material, which overcomes the limitations of high impedance associated with organic polymer insulator-based materials. In this current study, assembled by CABB which was certified as an available positive frictional material, TENG with a sandwiched structure of ITO/c-TiO 2 (compact TiO 2 )/m-TiO 2 (mesoporous TiO 2 )/CABB - the poly tetra fluoroethylene (PTFE)/Al exhibits appropriate performance on environmental stability and output capacity. A comparison of the fabrication process showed that spraying is an inexpensive method to prepare large-scale functional films of CABB TENG with brilliant relative dielectric constant and work function (W f ) difference that possess more distinguished output characteristics. This was confirmed by the appearance of higher open-circuit voltage of 105 V, larger short-current density of 2.45 mA/m 2 at 0.25 Hz motion parameter, and more abundant power density output of 0.76 W/m 2 under a higher frequency of 10 Hz. Further study clearly confirmed that both higher frequency and larger contact area are conducive to the total output power, while terminal charging speed is inversely or positively proportional with capacitance or mechanical frequency. The final physical display effect showed that spraying with CABB TENG could light up at least 53 commercial yellow LEDs, holding decent energy conversion ability. This confirms its efficiency, high throughput, and cost efficiency.
Abstract Electronic skins (E‐skins) are poised to revolutionize human interaction not only with one another but also with machines, electronics, and surrounding environment. However, the wearable E‐skin that simultaneously offers multiple sensing capabilities, high sensitivity, and broad sensing ranges remains a great challenge. Here, drawing inspiration from human haptic perception, a multimodal, ultrasensitive, and biomimetic E‐skin (MES) founded on micro‐frustum ionogel is developed based on iontronic capacitive and triboelectric effects for imaginary keyboard and multifunctional haptic cognition. Leveraging simultaneously the ionogel as capacitive layer and triboelectric layer, the MES enables human‐dermis perception performances of high sensitivity (357.56 kPa −1 ), low limit of detection (0.47 Pa), and broad linear detection range (0–500 kPa). Moreover, human finger joint movements can be precisely monitored by the attached MES and be transferred into accurate typed letter information on an imaginary keyboard. More importantly, by harnessing signal acquisition/processing circuits and machine learning, the real‐time haptic cognition of different materials, surface roughness, and contact pressure can be achieved by the MES, which endows the advancement of interaction between next‐generation intelligent robot and physical environment. Consequently, the proposed MES demonstrates impressive potentials in the fields of wearable electronics, human–machine interaction (HMI), and Artificial Intelligence (AI).
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