Spherical Magnetoelastic Generator for Multidirectional Vibration Energy Harvesting

Abstract

Vibration is a common, usually wasted energy, and an attractive target for sustainable electricity generation. In this work, we introduce a new working mechanism to the vibration energy harvesting community by contributing a spherical magnetoelastic generator (S-MEG), which permits multidirectional vibration and is highly adaptable to many natural oscillation frequencies, exhibiting a resonant frequency of 24 Hz and a relatively wide working bandwidth of 15 Hz in the low-frequency range. It also features a low internal impedance of 70 Ω, which can respectively deliver a maximum short-circuit current density of 7.962 A·m–2 and a power density of 15.1 mW·m–2. To demonstrate the capability of S-MEG for ambient vibration energy harvesting, a 220 μF commercial capacitor was successfully charged to 2 V within 25 s, sustainably driving wearable bioelectronics for multiple physiological information monitoring. It could also harvest multidirectional vibration energy from both hand-shaking and bicycle-riding, generating approximately 2.5 mA and 6 mA alternating current from the motions, respectively, even with heavy perspiration or on a rainy day without the need for encapsulation. In summary, this work brings forth an appealing platform technology to the community of vibration energy harvesting, holding a collection of compelling features, including high current density, low inner impedance, intrinsic waterproofness, and scalability for large-scale vibration energy harvesting.

Advances in Smart Photovoltaic Textiles

“…More importantly, the soft MEGs are intrinsically waterproof since the magnetic fields can penetrate water with negligible intensity loss. Thus, they demonstrate stable performance as wearable and implantable power sources without the need of an encapsulation layer. − This could be essentially compelling since the working environment of a bioelectronic device holds high humidity, no matter if they are skin-interfaced devices or in an implanted format.…”

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“…Examples include epidermal, − wearable, − and implantable bioelectronics. − These devices enable continuous, noninvasive monitoring of vital physiological signals in real time, comfortably providing clinically relevant information for disease diagnosis, preventive healthcare, and rehabilitation. − These devices are particularly promising for managing chronic diseases like cardiovascular issues, metabolic disorders, and diabetes, which are of significant in an aging population. − During health crises like the COVID-19 pandemic, they can reduce the need for hospital visits and readmissions . Beyond bioelectronics, the versatility of flexible electronics extends to wearable energy harvesters, − robotic skins for haptic interfaces, − and smart skins for aircraft to measure aerodynamic parameters in situ . − The trend towards flexible electronics is also evident in fields like photonics, acoustics, , metamaterials, and etc. These devices are ultrathin, low-modulus, and lightweight, making them “mechanically invisible” when applied to objects with arbitrary surfaces. − …”

Stretchable Thermoelectric Fibers with Three-Dimensional Interconnected Porous Network for Low-Grade Body Heat Energy Harvesting

“…Wearable bioelectronics enable the change of the current reactive and disease-centric healthcare system to a personalized model with a focus on disease prevention and health promotion. − Sustainably driving them still remains highly desired and a great challenge. − Energy harvesting from the human body and its surrounding offers a promising solution to power wearable bioelectronics without the need for traditional batteries. − The human body can generate a continuous heat output of 40 mW cm –2 to maintain a stable body temperature, resulting in a temperature difference in a range of 5 to 40 K with the surrounding environment. − Thermoelectric materials and generators are widely adopted for body heat energy harvesting, which represents a compelling approach to provide a sustainable source for wearable bioelectronic devices. − …”