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The demand for economical and efficient data processing has led to a surge of interest in neuromorphic computing based on emerging two-dimensional (2D) materials in recent years. As a rising van der Waals (vdW) p-type Weyl semiconductor with many intriguing properties, tellurium (Te) has been widely used in advanced electronics/optoelectronics. However, its application in floating gate (FG) memory devices for information processing has never been explored. Herein, an electronic/optoelectronic FG memory device enabled by Te-based 2D vdW heterostructure for multimodal reservoir computing (RC) is reported. When subjected to intense electrical/optical stimuli, the device exhibits impressive nonvolatile electronic memory behaviors including approximate to 10(8) extinction ratio, approximate to 100 ns switching speed, >4000 cycles, >4000-s retention stability, and nonvolatile multibit optoelectronic programmable characteristics. When the input stimuli weaken, the nonvolatile memory degrades into volatile memory. Leveraging these rich nonlinear dynamics, a multimodal RC system with high recognition accuracy of 90.77% for event-type multimodal handwritten digit-recognition is demonstrated.

The biosafety and sustainability of inorganic perovskites or organic piezopolymers is a major concern in the field of wearable piezoelectric sensors. Naturally occurring, silk fibroin (SF), is a promising alternative for the realization of organic piezoelectric devices due to its excellent biocompatibility and tunable material properties. Nevertheless, its scope for practical sensing applications is limited by the weak innate piezoelectricity of 1 pC N−1. This research aims to improve the piezoelectricity of pristine SF by intrinsically growing non-toxic metal-free perovskite (MFP) to achieve organic and bendable silk fibroin-metal free perovskite (SF-MFP) composite films. The increase in MFP loading has an influence on the resulting morphology and crystallinity of SF-MFP films. In comparison to pristine SF, the films with the highest perovskite loading exhibit an enhanced normal piezoelectric response of 4.6 pm V−1. The poled SF-MFP sensors display an appreciable sensitivity of 0.61 ± 0.05 V N−1 with a fast response time and outstanding stability arising from a synergistic combination of mechanically robust SF and piezoelectric MFP. Furthermore, these sensors can detect various joint bending and muscle movements in human subjects, proving their suitability for wearable bioelectronics. This research demonstrates the potential of biomaterials and organic perovskites for the development of biocompatible and sustainable wearable piezoelectric solutions. © 2023 Wiley-VCH GmbH.

Harvesting energy from flow using vortex-induced vibration (VIV) piezoelectric transducers has gained significant attention in recent decades due to their advantages, such as simple structure, blade-less layout, and low maintenance costs. However, most existing studies have focused on designing and analyzing a single piezoelectric energy harvester (PEH), without investigating the fluid-structure interaction and coupling of multiple PEH arrays. Here, we conducted an experimental study using a 2 x 2 PEH array to investigate its dynamic response under different wind speeds and spacings. Results show that the output voltage of the PEH array increases as the vertical spacing decreases, and the maximum average output voltage of 20.6 V per PEH is obtained when the minimum vertical spacing, maximum horizontal spacing, and resonance wind speed conditions are met. Compared to a single PEH, the 2 x 2 array arrangement increases the average output voltage by up to 168%. Additionally, the average output power under the resistance of 1 M omega increases by 629% to 4.3x10-4 W per PEH, and the maximum output power increases by 792% to 5.3x10-4. Experiments indicate that the vortex shedding coupling can induce higher vibration in a well-defined array, which paves a new way for developing bladeless wind farms.

Piezoceramics with global porosity and local compaction are highly desired to exploit the combination of mechanical and electrical properties. However, achieving such a functional combination is challenging because of the lack of techniques for applying uniform pressure inside porous ceramic green parts. Nature provides many examples of generating strong forces inside the macro and micro channels via the state transformation of water. Inspired by these phenomena, we present a technique of "ice and fire{''

Insufficient power output and poor wearability present significant challenges to the real-world implementation of existing footwear energy harvesters. Herein, we propose a leaf-spring-based motion converter that converts the low-frequency linear motion from footstep activity into the high-speed rotation of the electromagnetic generator and achieves high-performance power output and wearability. The motion converter employs a moderate stiffness leaf spring coupled with bearings to transfer vertical displacement of the heel into horizontal deformation and absorb shock at the footstep touchdown moment. A ratchet clutch is utilized to switch the working modes of the generator between the stance and swing phases. We characterized the dynamic response of the motion converter and developed an analytical model to predict the power output of the system. Furthermore, we fabricated a lightweight and compact prototype and tested it under pseudo and natural walking conditions. The prototype achieves a displacement amplification ratio of up to 2.2 and reduces acceleration amplitude at touchdown by 10.7% compared with walking without the device. At a stride frequency of 1 Hz, our prototype shows an open-circuit voltage of 20 V, short-circuit current of 0.4 A, a peak power of 1.88 W, and a power density of 15.2 mW/cm3, higher than the previously reported footwear energy harvester.

Harnessing abundant kinetic water energy in diverse forms of river flows, ocean waves, tidal currents, raindrops, and others, is highly attractive to ease the energy crisis and satisfy the demands of scattered sensor network nodes in the Internet of things. Among them, raindrops, widely and ubiquitously distributed in nature and ambient living life, have been extensively explored and regarded as significant renewable energy carriers. Extensive efforts have been made to investigate droplet-based electricity nanogenerators in fundamental mechanism, performance, and applications for achieving sustainable energy demands of the rapidly developing society over the past decade. In this review, we introduce the remarkable progress in this field and discuss the fundamental mechanisms of droplet energy harvesting technology for achieving high-power generation. More significantly, a systematic review of droplet energy harvesting in different two-phase interfaces, including liquid–solid, liquid–liquid, and liquid–gas interfaces, is provided. Finally, this survey reveals that droplet-based electricity generators present vast potential in the power supply. At the same time, several development challenges and prospective solutions are discussed to spur future technological advancements. © 2024 The Authors. Droplet published by Jilin University and John Wiley & Sons Australia, Ltd.