Adhikari Pashupati R, Tasneem Nishat T, Reid Russell C, Mahbub Ifana
Department of Mechanical and Energy Engineering, University of North Texas, 3940 N Elm St, Suite F101, Denton, TX, 76207, USA.
Department of Electrical Engineering, University of North Texas, Denton, TX, 76207, USA.
Sci Rep. 2021 Mar 3;11(1):5030. doi: 10.1038/s41598-021-84414-3.
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 AlO and SiO with 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/cm was 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.
对自供电可穿戴传感器需求的不断增加，促使人们迫切需要开发能够可靠且充分地为这些设备供电的能量收集系统。在过去十年中，基于反向介电电润湿（REWOD）的机械运动能量收集技术得到了发展，即在外部施加的机械力作用下，电解质在两个不同电极之间被调制（反复挤压）以产生交流电流。在这项工作中，我们探索了电解质浓度、电介质和电介质厚度的各种组合，以利用REWOD能量收集器产生最大输出功率。为了实现完全自供电的可穿戴传感器，采用了“零外加偏置电压”方法。使用三种不同浓度的氯化钠水溶液（NaCl - 0.1 M、NaCl - 0.5 M和NaCl - 1.0 M）作为电解质。同样，电极采用三种不同电介质厚度（100 nm、150 nm和200 nm）的AlO和SiO制成，并额外添加一层CYTOP以实现表面疏水性。使用包括电阻器、电容器和代表收集器的电流源的集总元件对REWOD能量收集器及其电极 - 电解质层进行建模。在不使用任何外部偏置电压的情况下，在3 Hz的外部激励频率和最佳外部负载下，展示了功率密度为53.3 nW/cm的交流电流产生。使用推导的理论模型对实验结果进行了分析验证。与先前报道的工作相比，该收集器在品质因数方面表现出卓越的性能。这项工作的新颖之处在于将分析建模方法与实验验证相结合，二者共同作用可在无需任何外部偏置电压的情况下大幅提高REWOD收集的功率。
