Experimental Study of Flexible Electrohydrodynamic Conduction Pumping for Electronics Cooling

Abstract

As modern day electronics develop, electronic devices become smaller, more powerful, and are expected to operate in more diverse configurations. However, the thermal control systems that help these devices maintain stable operation must advance as well to meet the demands. One such demand is the advent of flexible electronics for wearable technology, medical applications, and biology-inspired mechanisms. This paper presents the design and performance characteristics of a proof of concept for a flexible Electrohydrodynamic (EHD) pump, based on EHD conduction pumping technology in macro- and meso-scales. Unlike mechanical pumps, EHD conduction pumps have no moving parts, can be easily adjusted to the micro-scale, and have been shown to generate and control the flow of refrigerants for electronics cooling applications. However, these pumping devices have only been previously tested in rigid configurations unsuitable for use with flexible electronics. In this work, for the first time, the net flow generated by flexible EHD conduction pumps is measured on a flat-plane and in various bending configurations. In this behavioral characteristics study, the results show that the flexible EHD conduction pumps are capable of generating significant flow velocities in all size scales considered in this study, with and without bending. This study also proves the viability of screen printing as a manufacturing method for these pumps. EHD conduction pumping technology shows potential for use in a wide range of terrestrial and space applications, including thermal control of rigid as well as flexible electronics, flow generation and control in micro-scale heat exchangers and other thermal devices, as well as cooling of high power electrical systems, soft robotic actuators, and medical devices.

Overview of electrohydrodynamic conduction pumping

“…阳极周围电场强化作用尤为明显。Christophe 等 [67,68] 利用垫圈式对称电极获得了非零静压。 Seyed-Yagoobi 等 [69,70] EHD conduction pumping [70] 近年来，Seyed-Yagoobi 等 [71,72] 首次提出了柔性电 导泵的概念，采用丝网印刷技术，将银导电油墨沉 积于柔性聚酯基板之上，制作出不同规格的柔性电 导泵。他们的实验结果证明柔性泵无论是弯曲还是回 到原始状态，均不显著损失泵的性能。柔性电导泵与 传统刚性电导泵性能相似，产生速度在同一数量级。 Cacucciolo 等 [33] 采用成熟的弹性体加工技术，创新设 计了电极嵌入式可伸缩柔性泵。需要说明的是，文献 [33] 关注的是加工技术与电流体泵的结合，因此同时 设计了注入泵和传导泵。如图 9 所示，泵的主体材质 为聚二甲基硅氧烷(PDMS)，重量仅 1g，其尺寸 为 75mm×19 mm×1.3 mm，流体通道尺寸为 55 mm× [70] Tab.1 Dimensions of electrodes and electrode spacing [70] 名称 pump to a bending fluidic actuator [33] 图 11 单相流流动分布控制实验系统 [74] Fig 11 Experimental system of single-phase flow distribution control [74] 文献 [33] 还展示了可伸缩泵在可穿戴设备热控和 [74] (a)…”

A variable stiffness soft gripper with integrated ion-drag pump

“…The asymmetrically spaced electrodes ensure that there is a net flow of fluid along the pump. Typically EHD pumps generate tens of kPa of pressure and up to 10 ml/min of flowrate [30] [31], and find have found applications in cooling [32], [33] as well as actuation [30], [34], [35].…”