Digital Microfluidic Device for Hotspot Cooling in ICS Using Electrowetting on Dielectric

Abstract

To meet the increasing demand of efficient cooling performance in small scale, this paper presents a digital microfluidics (DMF) microscale liquid cooling system which works on the principle of electrowetting on dielectric (EWOD). In EWOD DMF, fluids are handled drop-wise by external electric field. When the dispensed liquid droplet arrives at the hotspot by EWOD DMF operation, it picks up heat and removes heat when it leaves. This process can be repeated for a series of droplets by using a completely automated LabVIEW controlled system connected to the PCB package. With the help of indium tin oxide (ITO) thin film resistance temperature detectors (RTD) and pre-calibrated temperature coefficient of resistance (TCR) data, the temperatures of the hotspot before and after the residence of liquid droplet (i.e., cooling) can be recorded for different frequencies (dwelling time period of droplet on the hotspot) of the drop motion and varying heater power. Future work will involve RTD resistance data collection to plot the heat flux and the temperature difference (before and after cooling) for different frequencies of drop motion. Although the primary focus is to study single phase cooling, the DI water drop will experience considerable evaporation resulting in higher cooling performance. The single phase cooling studies will help in establishing a robust platform for future two-phase cooling analysis in which evaporation effects will be considered.

Single-Sided Digital Microfluidic (SDMF) Devices for Effective Coolant Delivery and Enhanced Two-Phase Cooling

“…This low-energy surface is also free from the hydrophobic polymer coating that behaves as an additional thermal barrier. However, DMF-based cooling studies [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ] previously reported critically require the hydrophobic polymer coating on top of the hot spot to facilitate droplet transportation. As indicated in Figure 1 , while a cooling droplet passes over the target hot spot, the heat is rejected based on sensible heat transfer, which limits the level of applicable heat flux.…”

“…In recent years, DMF has drawn attraction as a liquid-handling platform for effective cooling of target heating sources [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Unlike conventional cooling technologies such as heat pipes [ 29 , 30 ], heat spreaders [ 31 , 32 ], microchannel-guided liquid cooling [ 33 , 34 ], and jet impingement cooling [ 35 ], DMF does not require additional mechanical components such as pumps, valves, microchannels, and capillary wick structures for coolant delivery.…”

“…Despite numerous studies of DMF-based cooling previously reported [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ], such a single-phase heat transfer approach cannot be used for high-heat-flux (>100 W/cm 2 ) applications, for example, high power density semiconductors such as graphic processing units (GPUs), power amplifiers, and insulated gate bipolar transistors (IGBTs). In order to achieve high-heat-flux dissipation, the two-phase heat transfer mechanism needs to be integrated [ 29 , 30 , 34 ].…”

Development of a simple, portable, colorimetric arsenic sensor based on Molybdenum Blue Chemistry

“…In the past 25 years, there has been a surge of interest in the field as researchers miniaturize traditional macro-scale processes to micro-dimensions, and explore new aspects of science previously unseen from a macro-scale vantage point. This technology has been used by studies in a range of applications, from clinical medicine and microbiology, to electronics and the oil industry (Hettiarachchi et al 2007;Gómez-sjöberg et al 2005;Bindiganavale et al 2012;Fadaei et al 2011). In comparison to their macro-scale counterparts, microfluidic processes have the following advantages: faster reaction times and better process-control; reduced waste generation and reagent consumption; system compactness and parallelization; and reduced cost and disposability.…”

Development of a simple, portable, colorimetric arsenic sensor based on Molybdenum Blue Chemistry

“…In the past 25 years, there has been a surge of interest in the field as researchers miniaturize traditional macro-scale processes to micro-dimensions, and explore new aspects of science previously unseen from a macro-scale vantage point. This technology has been used by studies in a range of applications, from clinical medicine and microbiology, to electronics and the oil industry (Hettiarachchi et al 2007;Gómez-sjöberg et al 2005;Bindiganavale et al 2012;Fadaei et al 2011). In comparison to their macro-scale counterparts, microfluidic processes have the following advantages: faster reaction times and better process-control; reduced waste generation and reagent consumption; system compactness and parallelization; and reduced cost and disposability.…”