As discussed in a recent post, for the last few years power consumption has become one of the predominant issues in chip design, leading the industry down the path to multi-core processors and beyond. But clever architectural designs and sophisticated circuit techniques are only a few of a myriad of ways in dealing with the problem – how about improving the way chips are being cooled? This might seem at first like a band aid for power inefficient design, until the realization sets in that the industry is way past the point where a band aid might help and that already there are major problem with cooling chips; simply take a look at some of the monstrosities that can be found in desktop PCs and servers these days. Well, there might be some relief on the horizon, curtsey of Purdue University and their recent breakthrough in chip cooling. Using what the team refers to as ionic wind engines, the researchers were able to increase the heat-transfer coefficient by 250% percent when combined with a traditional fan.  A higher heat-transfer coefficient indicates a more efficient cooling process, thus leading to a possible decrease in heat-sink and fan sizes that might be required to cool a particular component, which in turn might enable thinner electronic devices.

The key idea that leads to the vastly improved heat-transfer coefficient lies in the research team’s ability to increase the airflow at the surface of the chip, which is where the ionic wind engines come into play. These engines are created through closely spaced electrodes near the chip surface. When voltage is applied, electrically charge atoms, or ions, travel between the negatively charged electrode and the positively charged electrode. However, on their journey they encounter positively charged air particles, and become positively charged atoms themselves. Instead of continuing their journey the positively charged atoms do a u-turn so to say and proceed back to the negative electrode, thus completing the ionic wind engine. The oppositely charged electrodes are not placed next to each other as one might initially assume, but rather are placed vertically on top of each other with a fixed spacing in-between. This minimizes the no-slip effect that is caused when air flows over an object, by ensuring that the molecules closest to the surface of the object don’t remain stationary.  In other words, the ionic wind engines ensure there is a good molecule circulation away from the chip surface, where it is needed most – which is not the case with traditional air-based cooling.

There is still plenty of work that needs to be done and commercial applications are not expected for at least another three years by which time the team hopes to have the technology working reliably at the micron scale. Nevertheless, some cooling relief seems to be on the horizon.