There is an abundance of low-frequency and irregular human motion energy that can be harvested. In this work, a non-resonant rotational electromagnetic energy harvester (REH) for scavenging low-frequency (<10 Hz) and irregular human motion is presented. The energy harvester simply introduces a cylindrical stator and a disk-shaped rotor forming a movement of a higher pair. Without any complicated transmission mechanism, the rotor can easily rotate around the stator by magnetic attractive force. Driven by a broadband frequency vibration, the magnetic rotor is coupled with surrounding wound coils to operate electromagnetic energy harvesting. Theoretical and experimental investigations of the REH are studied, and numerical simulations show good agreement with the experimental results. The treadmill tests at various motion speeds are performed to demonstrate the advantage of the REH in harvesting energy from irregular human motion. At a driving frequency of 8 Hz, the electromagnetic coils can provide the maximum power of 10.4 mW at a load resistance of 100 Ω. The REH exhibits outstanding output performance and has potential applications for powering intelligent wearable or portable electronic devices.
Summary This article proposed a high-performance triboelectric-electromagnetic hybrid wind energy harvester (WEH). By adopting the revolution and rotation movements of tapered rollers, which serve as both the rotor of the electromagnetic generator (EMG) part and freestanding layers of the triboelectric nanogenerator (TENG) part, the WEH can work as a sustainable power source and a self-powered wind speed sensor. When the wind speed is 12 m/s, super-high open-circuit voltage peaks of 47.4 and 683 V can be achieved by the EMG and TENG, respectively, corresponding to the high-power outputs of 62 and 1.8 mW. It was demonstrated that the WEH can easily light up over 600 red light-emitting diodes and even a 5-W globe light. A self-powered wireless temperature and humidity sensing network was also systematically demonstrated. In summary, the proposed WEH exhibits bright future toward IoT applications, such as in border detection, smart buildings, and so on.
This paper proposes an impact-based micro piezoelectric energy harvesting system (PEHS) working with the frequency up-conversion mechanism. The PEHS consists of a high-frequency straight piezoelectric cantilever (SPC), a low-frequency S-shaped stainless-steel cantilever (SSC), and supporting frames. During the vibration, the frequency up-conversion behavior is realized through the impact between the bottom low-frequency cantilever and the top high-frequency cantilever. The SPC used in the system is fabricated using a new micro electromechanical system (MEMS) fabrication process for a piezoelectric thick film on silicon substrate. The output performances of the single SPC and the PEHS under different excitation accelerations are tested. In the experiment, the normalized power density of the PEHS is 0.216 μW·g−1·Hz−1·cm−3 at 0.3 g acceleration, which is 34 times higher than that of the SPC at the same acceleration level of 0.3 g. The PEHS can improve the output power under the low frequency and low acceleration scenario.
in diverse application fields, for example, entertainment, robotics, [3] virtual reality/ augmented reality (VR/AR), [4] smart factory, and so on. [5-7] Beyond that, HMI can even be extended to medical rehabilitation, [8] extreme environmental operation, [9] remote education, telemedicine, and other fields. [10,11] With the aid of technology advance, the effectiveness and intuitiveness of interaction are more demanding. The solutions of HMI are switching from the conventional control terminals, such as keyboard, touchpad, and joystick, toward more diversified and creative alternatives. As a result, many new interaction mechanisms have been developed to satisfy the need for efficient and intuitive interaction. [12] For instance, vision recognition can identify facial features and realize human motion capture to complete motion mapping. [13,14] Evolving together with the fast-growth of wearable electronics and IoT, modern HMI are developing toward self-powered capability [15-17] and flexible wearable compatibility. [12] Self-powered electronics are of increasing importance due to their environmentally friendly and self-sustainability, providing an possible solution in alleviating the global energy crisis and environmental pollution. [18-22] Many self-powered electronics have been developed by integrating different energy harvesting technologies, such as electromagnetic, [18-20] piezoelectric, [21,22] and triboelectric. [17,18,23-26]. Based on the coupling of triboelectrification and electrostatic induction, triboelectric nanogenerators (TENGs) have been demonstrated as promising candidates [27-33] for various selfpowered sensing or self-driven controlling [16,17,25] applications. For example, Luo reported a flexible and durable wood-based TENG for self-powered sensing in athletic big data analytics. [34] It can be used to smart sport monitoring and assisting. It also can be used to promote the development of big data analytics in intelligent sports industry. TENG-based self-powered technology provides a creative way to realize HMI [35,36] because of its superior advantages such as self-generated signals, high output sensitivity, simple but diverse configurations, low cost, various material applicability, and flexibility. [34,37,38] In the past few years, there have been many HMI prototypes reported by using triboelectric mechanisms. [16,25,31,35,39-41] In recent years, human-machine interface technology has entered a period of rapid development in the global scope. It has gradually expanded from the initial field of medical rehabilitation to engineering bionics, virtual reality, space technology, deep-sea assignments, atomic energy technology, remote education, and other areas. Herein, an innovative, self-powered delta-parallel human-machine interface (DT-HMI) for 3D sensing and control is proposed. By using three pairs of triboelectric nanogenerator (TENG) sensing gears based on both contact-separation and sliding modes of triboelectric effect, the positive and negative rotation of the gears and rotation angles ca...
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