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 flexible electrohydrodynamic (EHD) pumps, based on EHD conduction pumping technology in macro- and mesoscales. Unlike mechanical pumps, EHD conduction pumps have no moving parts, can be easily adjusted to the microscale, 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 in various configurations. In this 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. The selection of working fluid for EHD conduction pumping is also a topic of discussion. Novec Engineered Fluids have been a popular choice for EHD pumping; however, long-term testing has shown that some Novec fluids degrade over time.

A Review on Electrohydrodynamic (EHD) Pump

“…EHD cooling devices are designed in various shapes. O’Connor et al used a comb and circular-shaped electrodes ( Figure 8 a), allowing the pump to produce significant flow rates with and without bending [ 151 ]. Zeng et al used EHD gas pumps with needle electrode strips ( Figure 8 b) to investigate the effects of the needle-electrode arrangement, the structure of the mesh electrodes, the gap between the needle tip and the mesh, and the distance on the output speed and power consumption of the ion air pump [ 152 ].…”

“…For example, Blanc et al [ 156 ] experimented with functional fluidic EHD pumps for heat pipe solutions for the thermal management of embedded missiles. O’Connor et al focused on electrical equipment cooling and proposed the possibility of being incorporated into flexible electronics [ 151 ]. Moreover, Nishikawara and Yagoobi presented the pumping performance of a micropump with three pairs of perforated electrodes designed to be fabricated and integrated into a high-heat flux evaporator embedded in an electronics cooling system [ 157 ].…”

A Review on Electrohydrodynamic (EHD) Pump

“…EHD cooling devices are designed in various shapes. O'Connor et al have used a comb and circular-shaped electrodes (Figure 8 (a)) and made the pump produce significant flow rates with and without bending [145]. Zeng et al used EHD gas pumps with needle electrode strips (Figure 8 (b)) to investigate the effects of the arrangement of the needle electrodes, the structure of the mesh electrodes, the gap between the needle tip and the mesh, and the distance on the output speed and power consumption of the ion air pump [146].…”

“…For example, Blanc et al [156] experimented with functional fluidic EHD pumps for heat pipe solutions for the thermal management of embedded missiles. O'Connor et al focused on electrical equipment cooling and proposed the possibility of being incorporated into flexible electronics [145]. Moreover, Nishikawara and Yagoobi provided the pumping performance of a micropump with three pairs of perforated electrodes designed to be fabricated and integrated into a high heat flux evaporator embedded in an electronics cooling system [157].…”

Numerical analysis of electro-convection in dielectric liquids with residual conductivity

“…Meanwhile, both analytical and numerical solutions are performed to discuss the effect of the electric field strength, system geometry, and alternating current (AC) frequency on the velocity and pattern of the aforementioned EHD flow. Furthermore, the electrohydrodynamic flow based on the conduction model attracts the attention of researchers for the application of conduction pumping 3,[27][28][29] . This specific application is expected to be used in many engineering fields, including space thermal control and flexible microscale pumping, due to its advantages of having no mechanical components, no noise, easy miniaturization 30 .…”