Vibration energy harvesting is a promising solution for powering battery-free IoT systems; however, the instability of ambient vibrations presents significant challenges, such as limited harvested energy, intermittent power supply, and poor adaptability to various applications. To address these challenges, this paper proposes ViPSN2.0, a modular and reconfigurable IoT platform that supports multiple vibration energy harvesters (piezoelectric, electromagnetic, and triboelectric) and accommodates sensing tasks with varying application requirements through standardized hot-swappable interfaces. ViPSN 2.0 incorporates an energyindication power management framework tailored to various application demands, including light-duty discrete sampling, heavyduty high-power sensing, and complex-duty streaming tasks, thereby effectively managing fluctuating energy availability. The platform’s versatility and robustness are validated through three representative applications: ViPSN-Beacon, using an ultra-lowcost structural PZT (ϕ35 mm, <0.002 $) to enable a BLE advertisement from a single transient fingertip press with 100 m line of sight; ViPSN-LoRa, supporting wireless communication powered by wave vibrations in actual marine environments (Bohai Bay) with per-uplink task energy compatible with kilometer-scale field links; and ViPSN-Cam, enabling intermittent image capture and wireless transfer, delivering one frame approximately every 15 s under typical conditions. Experimental results demonstrate that ViPSN 2.0 can reliably meet a wide range of requirements in practical battery-free IoT deployments under energy-constrained conditions.

Human-motion energy harvesting is emerging as a promising solution for wearable electronics and devices, offering a sustainable power source that extends operational longevity and enhances durability. However, current techniques and prototypes have yet to achieve fully interactive, battery-free functionality. This paper presents a battery-free interactive gaming system powered by energy harvested from transient fingertip motion. To ensure the reactivity, interactivity, and stability of the fingertip motion harvester (FMH), we employ a multistable structure. The FMH unit provides a reliable energy solution by utilizing precharged potential energy within dynamically varying potential wells. Additionally, the integration of a bistable screen design facilitates seamless gaming experiences, decouples game logic from user interface mechanics, and ensures rapid system recovery after power interruptions. Beyond advancing fundamental research, this work pioneers a practical battery-free interaction paradigm based on fingertip motion, with potential for broader battery-free user interfaces and low-power interactive systems.

Vibration energy harvesters have been widely investigated to supply sustainable power for devices in the Internet of Things (IoT). Despite the advances in vibration energy harvesters, there still remain challenges in the design and optimization of energy harvesters to meet the increasing power demand of long-range IoT applications. In this article, an auxetic piezoelectric energy harvester with tapered thickness (TAEH) is proposed to improve the efficiency of energy harvesting by achieving the uniform stress and high average stress. Compared with traditional auxetic piezoelectric energy harvester with uniform thickness (UAEH), the stress distribution with tapered thickness is more uniform, which can contribute to a higher power output with lower maximum stress. Furthermore, the multiobjective optimization is used to further improve the average stress values without increasing the maximum stress, thus increasing the energy output. Finite element analysis is performed to validate the performance of the energy harvesters. In the experimental validation, it is found that with the tapered thickness introduced to the auxetic energy harvester, the maximum power output and power density of TAEH can be increased by 212.84% and 279.08%, respectively, compared with UAEH. After the optimization, these two indices of the optimized TAEH (OTAEH) are further increased by 24.32% and 27.59%, respectively. Specifically, a high power density of 0.148 mW/g is achieved in the OTAEH, indicating its high vibration energy harvesting performance with lightweight. Finally, it is demonstrated that the OTAEH can generate more than 40.94 mJ within 27.6 s to successfully power an IoT device for temperature sensing and long-range data transmission.

For boosting output power, frequency-up methods like gear train and plucking are introduced into pendulum-based electromagnetic energy harvesters (EEHs). Still, the gear train and plucking methods have the problems of high manufacturing costs and high energy loss, respectively. To address the above issues, inspired by biological grooming behavior, we present a low-cost, high-efficiency EEH utilizing 3D printing. This device is excited by an asymmetric stiffness pendulum, induced by an oblique cantilever beam, converting the ultra-low frequency of human motion into high-speed, unidirectional rotation of the rotor. The energy density comparison between the sandwich and back iron structure of the EEH is made by the simulation, and then parameters are selected. The bench-top swing experiment system is established to test the performance of the EEH, and the established equivalent electromagnetic model discusses the load resistance result. The feasibility of human walking for powering the Internet of Things (IoT) device is explored when wearing the EEH. The bench-top test result shows that the EEH can reach the normalized power of 1.07 · 10-4 W/(Hz ·°) and normalized power density of 6.6 W/(m3·°). Through human testing at a walking of 1 km/h, the IoT device can run normally, showing great potential for achieving self-power and cost-effective IoT devices.

The increasing number of distributed Internet of Things (IoT) devices makes the power supply a prominent issue, which limits the extent and lifetime of ubiquitous IoT networks. Mechanical energy harvesting (MEH) technology transforms the local mechanical energy into useful electricity. It provides a solution for the realization of self-sustainable motion-powered IoT applications. Given the volatile feature of most ambient vibrations, energy management methods are necessary for matching the unstable energy supply from the MEH sources and the energy demand of timely IoT tasks. This paper summarizes and analyzes two energy buffer-release mechanisms (EBRM) from mechanical and electrical aspects, respectively, for ensuring the robust operation of motion-powered IoT systems. Rather than emphasizing harvesting more energy from vibrations, as most of the previous studies did, we focus on energy neutrality among the mechanical, electrical, and cyber ingredients. A preset energy release threshold realized in either a mechanical or electrical way ensures the completion of every fundamental atomic task. The necessity of EBRM is demonstrated in three controlled experiments. Only those systems with a mechanical or electrical buffer-release mechanism can operate correctly.

Energy harvesting technology enables the battery-free realization of some sensing, computing, and connectivity functions. However, its promotion in battery-free human-computer interaction is relatively slow in comparison. There is a critical energy gap around interactive devices which are screen-focused and usually power-hungry. This energy gap can be narrowed down and filled up by selecting a proper display and taking a sophisticated hardware and software co-design. Motion-powered gameboy, the first robust personal mobile gaming device, is manufactured by combining the features of a bistable E-ink display and a quasi-static toggling motion energy harvester. With the hardware-software co-design, the amount of energy generated by the player's pinch action can adequately guarantee successful user interaction and preferable user experience. The design methodology of the motion-powered game-boy provides a valuable example for the development of motion-powered human-computer interactive devices.

The emerging energy harvesting technology facilitates the development of ubiquitous and everlasting battery-free motion detectors. This article introduces a robust design of the transient-motion-powered motion detector, which is called ViPSN-pluck. “ViPSN” is the acronym for the vibration-powered sensing node while “pluck” stands for the plucking-motion energy harvester. By using a piezo-magneto-elastic structure, ViPSN-pluck can efficiently harvest energy from a transient motion. By properly making good use of this tiny harvested energy, ViPSN-pluck can effectively carry out motion detection and Bluetooth low-energy (BLE) wireless communication. Given the concurrency of mechanical potential energy precharging and motion detection, the transient-motion plucking energy harvester used in ViPSN-pluck has the merit of high energy reliability. This unique feature is unprecedented in the solar and radio-frequency (RF) energy harvesting cases, which might suffer from energy outages under fluctuating irradiance or RF signal strength, respectively. The working principle of ViPSN-pluck, in particular, the dynamic characteristics of the plucking energy harvester and the energy matching between generation and utilization, are discussed in detail to demonstrate the robustness in operation. The cyber-electromechanical synergy among the mechanical dynamics, power conditioning circuit, and low-power embedded system is highlighted. The design methodology of ViPSN-pluck provides a valuable reference for the developments of future motion-powered Internet of Things devices.

The development of Internet of Things (IoT) has placed a strong demand on human motion detection technologies. Motion detectors acts an essential role in many civil applications, such as home security, occupancy and activity monitoring, retail analysis, etc. Emerging energy harvesting technologies provide promising solutions towards the ubiquitous and everlasting deployments of motion detectors. However, most existing battery-free solutions require special environmental conditions and suffer from frequent energy outages. Therefore, their applications are still very limited. This live demonstration exhibits a transient-motion-powered motion detector, named ViPSN-E, where "ViPSN" stands for vibration-powered sensor node [1]; "E" stands for an energy-mode device. ViPSN-E can carry out maintenance-free motion detection and wireless communication by making good use of the energy harvested from an instantaneous motion. The prototype of ViPSN-E is shown in Fig. 1. The system is developed based on ViPSN [1], an open-source development platform specified for vibration- powered IoT devices. ViPSN-E is composed of four parts: a piezo-magneto-elastic structure as energy harvester, a self- powered synchronized switch harvesting on inductor (SP- SSHI) interface circuit [2], an enhanced energy management unit, and a Bluetooth low energy (BLE) unit. The piezo- magneto-elastic harvester is composed of a low-cost piezoelectric cantilever and a pair of magnets, which are used to induce a plucking excitation in a transient and one-way movement.

In this article, we introduce a vibration-powered sensing node (ViPSN), a programmable Internet-of-Things (IoT) platform for the development of vibration-powered or motion-powered sensing and transmitting systems. It leverages the exploitation and utilization of ambient vibration energy by using a piezoelectric transducer. The roles and relations of six necessary modules, including energy generation unit (EGU), energy transduction unit (ETU), energy enhancement unit (EEU), energy management unit (EMU), energy user unit (EUU), and edge demonstration unit (EDU) are discussed in detail. In particular, an enhanced EMU is proposed by making necessary complements to an extensively used off-the-shelf integrated circuit (IC) solution for piezoelectric transducers. It provides more comprehensive energy storage indicating signals, such that the sensing, computing, and transmitting tasks can be carried out more robustly by keeping a good awareness of the remaining energy. Owing to the enhanced EMU design, vibration energy in various forms, such as intermittent and transient ones, can be more effectively harvested and utilized. The performance of ViPSN is evaluated, in terms of its lifetime and Quality of Service (QoS), under different vibration scenarios. The inclusive design and affiliated opensource project of ViPSN help build a new ecosystem for the research and development of vibration- or motion-powered IoT systems.