Increasing demand for self-powered wearable sensors has spurred an urgent need to develop energy harvesting systems that can reliably and sufficiently power these devices. Within the last decade, reverse electrowetting-on-dielectric (REWOD)-based mechanical motion energy harvesting has been developed, where an electrolyte is modulated (repeatedly squeezed) between two dissimilar electrodes under an externally applied mechanical force to generate an AC current. In this work, we explored various combinations of electrolyte concentrations, dielectrics, and dielectric thicknesses to generate maximum output power employing REWOD energy harvester. With the objective of implementing a fully self-powered wearable sensor, a “zero applied-bias-voltage” approach was adopted. Three different concentrations of sodium chloride aqueous solutions (NaCl-0.1 M, NaCl-0.5 M, and NaCl-1.0 M) were used as electrolytes. Likewise, electrodes were fabricated with three different dielectric thicknesses (100 nm, 150 nm, and 200 nm) of Al2O3and SiO2with an additional layer of CYTOP for surface hydrophobicity. The REWOD energy harvester and its electrode–electrolyte layers were modeled using lumped components that include a resistor, a capacitor, and a current source representing the harvester. Without using any external bias voltage, AC current generation with a power density of 53.3 nW/cm2was demonstrated at an external excitation frequency of 3 Hz with an optimal external load. The experimental results were analytically verified using the derived theoretical model. Superior performance of the harvester in terms of the figure-of-merit comparing previously reported works is demonstrated. The novelty of this work lies in the combination of an analytical modeling method and experimental validation that together can be used to increase the REWOD harvested power extensively without requiring any external bias voltage.
This content will become publicly available on March 19, 2025
A dual energy harvester based upon the magnetoelectric mechanism is reported. The harvester can generate ∼52.1 mW under simultaneously applied magnetic field and ultrasound in porcine tissue operating under safety limits.
more » « less- Award ID(s):
- 1916707
- NSF-PAR ID:
- 10499929
- Publisher / Repository:
- Royal society of chemistry
- Date Published:
- Journal Name:
- Energy & Environmental Science
- Volume:
- 17
- Issue:
- 6
- ISSN:
- 1754-5692
- Page Range / eLocation ID:
- 2129 to 2144
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract Energy harvesting from extremely low frequency magnetic fields using magneto‐mechano‐electric (MME) harvesters enables wireless power transfer for operating Internet of Things (IoT) devices. The MME harvesters are designed to resonate at a fixed frequency by absorbing AC magnetic fields through a composite cantilever comprising of piezoelectric and magnetostrictive materials, and a permanent magnetic tip mass. However, this harvester architecture limits power generation because volume of the magnetic end mass is closely coupled with the resonance frequency of the device structure. Here, a method is demonstrated for maintaining the resonance frequency of the MME harvesters under all operating conditions (e.g., 60 Hz, standard frequency of electricity in many countries) while simultaneously enhancing the output power generation. By distributing the magnetic mass over the beam, the output power of the harvester is significantly enhanced at a constant resonance frequency. The MME harvester with distributed forcing shows 280% improvement in the power generation compared with a traditional architecture. The generated power is shown to be sufficient to power eight different onboard sensors with wireless data transmission integrated on a drone. These results demonstrate the promise of MME energy harvesters for powering wireless communication and IoT sensors.
-
more » « less
Abstract Self‐sustainable energy generation represents a new frontier to significantly extend the lifetime and effectiveness of implantable biomedical devices. In this work, a piezoelectric energy harvester design is employed to utilize the bending of the lead of a cardiac pacemaker or defibrillator for generating electrical energy with minimal risk of interfering with cardiovascular functions. The proposed energy harvester combines flexible porous polyvinylidene fluoride–trifluoroethylene thin film with a buckled beam array design for potentially harvesting energy from cardiac motion. Systematic in vitro experimental evaluations are performed by considering complex parameters in practical implementations. Under various mechanical inputs and boundary conditions, the maximum electrical output of this energy harvester yields an open circuit voltage (peak to peak) of 4.5 V and a short circuit current (peak to peak) of 200 nA, and that energy is sufficient to self‐power a typical pacemaker for 1 d. A peak power output of 49 nW is delivered at an optimal resistor load of 50 MΩ. The scalability of the design is also discussed, and the reported results demonstrate the energy harvester's capability of providing significant electrical energy directly from the motions of pacemaker leads, suggesting a paradigm for biomedical energy harvesting in vivo.
-
more » « less
Abstract The technological promise of soft devices—wearable electronics, implantables, soft robotics, sensors—has accelerated the demand for deformable energy sources. Devices that can convert mechanical energy to electrical energy can enable self‐powered, tetherless, and sustainable devices. This work presents a completely soft and stretchable (>400% strain) energy harvester based on variable‐area electrical‐double‐layer (EDL) capacitors (≈40 µF cm−2). Mechanically varying the EDL area, and thus the capacitance, disrupts equilibrium and generates a driving force for charge movement through an external circuit. Prior EDL capacitors varied the contact area by depressing water droplets between rigid electrodes. In contrast, here, the harvester consists of liquid‐metal electrodes encased in a hydrogel. Deforming the device by ≈25% strain generates a power density ≈0.5 mW m−2. This unconventional approach is attractive because: (1) it does not need an external voltage supply to provide charge; (2) the electrodes themselves deform; and (3) it can work under various modes of deformation such as pressing, stretching, bending, and twisting. The unique ability of the harvester to operate underwater shows promising applications in wearables that contact sweat, underwater sensing, and blue energy harvesting.
-
more » « less
Abstract We present a phylogeographic study of at least six reproductively isolated lineages of new world harvester ants within the
Pogonomyrmex barbatus andP. rugosus species group. The genetic and geographic relationships within this clade are complex: Four of the identified lineages show genetic caste determination (GCD ) and are divided into two pairs. Each pair has evolved under a mutualistic system that necessitates sympatry. These paired lineages are dependent upon one another because theirGCD requires interlineage matings for the production of F1 hybrid workers, and intralineage matings are required to produce queens. ThisGCD system maintains genetic isolation among these interdependent lineages, while simultaneously requiring co‐expansion and emigration as their distributions have changed over time. It has also been demonstrated that three of these fourGCD lineages have undergone historical hybridization, but the narrower sampling range of previous studies has left questions on the hybrid parentage, breadth, and age of these groups. Thus, reconstructing the phylogenetic and geographic history of this group allows us to evaluate past insights and hypotheses and to plan future inquiries in a more complete historical biogeographic context. Using mitochondrialDNA sequences sampled across most of the morphospecies’ ranges in the U.S.A. and Mexico, we conducted a detailed phylogeographic study. Remarkably, our results indicate that one of theGCD lineage pairs has experienced a dramatic range expansion, despite the genetic load and fitness costs of theGCD system. Our analyses also reveal a complex pattern of vicariance and dispersal inPogonomyrmex harvester ants that is largely concordant with models of late Miocene, Pliocene, and Pleistocene range shifts among various arid‐adapted taxa in North America.
