Remote‐Controlled Droplet Chains‐Based Electricity Generators

Abstract

Harnessing ambient renewable mechanical energies for achieving carbon‐neutrality demands the rational design of materials and architectures which are favorable for both energy collection and conversion simultaneously. However, the direct coupling of energy collection and conversion modules leads to many unwanted problems such as material wearing, the spatial constraint for large‐scale integration, and low energy conversion efficiency. Herein, a remote‐controlled energy harvesting strategy that cleverly harnesses the unique advantage of diffusive, long‐range airflow within a confined capillary channel is developed. The reported device separates the energy collection unit, made of an elastic cavity that directly transforms external mechanical motion to pneumatic motion, from the conversion units, made of encapsulated droplet chains that serve to translate their recurring motion within the capillary channel into electrical output. In contrast to single‐drain electrode design for electricity generation from fresh droplets in open spaces, two drain electrodes are designed to collect and release electrostatically induced charges from recurring droplets in the confined channel, respectively, thereby eliminating unwanted charge accumulation on recurring droplets and leading to efficient output performance. The integration of multiple electricity generation units with such a two‐drain electrode architecture with a single energy collector improves the design resilience and relaxes the spatial limitation.

Water droplet energy harvesting

“…As a kind of high-entropy energy, significant progress has been made in harvesting droplet energy based on various mechanisms and showing decent perspectives of powering the worldwide-distributed electronics and sensing nodes, as shown in Figure 1. 19,29,[49][50][51][52][53][54][55][56][57] In 1867, a British scientist, Lord Kelvin invented the Kelvin water dropper based on electrostatic induction, regarded as an earlier classic droplet energy harvesting technology. 41,58,59 Then, the theories and models of raindrop energy harvesting relaying on the piezoelectric, 35,60 reverse electrowetting, 42,[61][62][63] and hydrovoltaic technology [64][65][66] are sequentially proposed, intending to practical applications in diverse selfpowered sensing systems.…”

A droplet‐based electricity generator incorporating Kelvin water dropper with ultrahigh instantaneous power density

“…[23][24][25][26][27][28][29][30] Showing a great leap in power density and efficiency by several orders of magnitude, a recently reported droplet-based electricity generator with transistor-inspired architecture overcomes the limitation of interfacial effect in conventional design, providing a new route to efficiently harvest water energy. 31 Triggered by this finding, a wave of progress has been accomplished to generate electricity at various interfaces such as liquid-liquid, 32,33 liquid-solid, [34][35][36] and liquid-gas interface, 37 from single droplet to droplet arrays, 38 from bubbles to water waves, 39 with a continuous leap in peak power density from 50 to 10 3 W/m 2 . 40 Despite the significant progress, the output performance of droplet-based electricity generator (DEG) is still constrained by the long precharging time and low surface charge density.…”

A constant-current generator via water droplets driving Schottky diodes without a rectifying circuit

“…2,3 Electricity generators made of common polymer materials only output alternative and pulsed current and require complex management circuit processing before usage. [4][5][6][7][8] If the generator itself has a rectification character, which can avoid energy loss caused by the rectification process, it further simplifies the management circuit and improves the energy conversion efficiency. 9,10 Among numerous material systems, semiconductors has shown broad application prospects in the fields of energy harvesting, integrated circuits, sensing systems, etc.…”