A Center for Sustainable Cloud Computing

While scientists have successfully reduced the size and costs of electronic components, a major challenge faced by such tiny devices is the absence of an optimum thermal and energy management technology. To bridge that gap, Elison Matioli and his colleagues at EPFL’s Power and Wide-band-gap Electronics Research Laboratory (POWERlab) have developed a novel microchannel network that not only cools electronic components but also makes them energy efficient.

Since electronic components are averse to high temperatures, they are usually cooled down by means of conventional fan-cooled heat exchangers or more complex fluid-carrying microchannels running through them. The microchannels need to be extremely narrow and small to have the required impact, but that necessitates a higher amount of pressure for proper flow of the fluid. That translates into higher energy consumption. To address that energy challenge, Matioli and others have integrated microfluidics and electronics within the same semiconductor substrate. This embedded approach is unlike state-of-the-art technology, where electronics and cooling are treated separately.

The EPFL researchers used a chip containing a thin layer of a semiconductor called gallium nitride (GaN) on top of a thicker silicon substrate. In a departure from existing techniques, they carved the microchannels within the substrate and aligned them with the parts of the chip that tend to heat up the most, thus helping the system cool down efficiently. For reducing the energy needed to pump the fluid through the microchannels, the researchers drew inspiration from the human circulatory system, which comprises larger blood vessels that become thinner and transform into capillaries in certain areas of the body. They designed the microchannel network with wider channels that taper in the exact location where the heat builds up more. This radically reduced the total amount of energy needed to push the fluid. Experiment results showed an unprecedented coefficient of performance (exceeding 10,000) for single-phase water-cooling of heat fluxes exceeding 1 kilowatt per square centimetre, corresponding to a 50-fold increase compared to straight microchannels.

The research paper “Co-designing electronics with microfluidics for more sustainable cooling” is published in the latest issue of Nature.

van Erp, R., Soleimanzadeh, R., Nela, L. et al. Co-designing electronics with microfluidics for more sustainable cooling. Nature 585, 211–216 (2020). https://doi.org/10.1038/s41586-020-2666-1