November 26, 2025 by University of Osaka
Collected at: https://phys.org/news/2025-11-mini-fridges-nanoscale-cooling-technique.html
As more devices get piled onto computer chips to increase processing power capacity, heat generation becomes increasingly concentrated. This heat must be removed to keep chip performance high, but is currently achieved by circulating water through millimeter-scale channels to cool nanosized hotspots. This scale mismatch reduces the cooling efficiency by consuming more water than necessary, also raising environmental concerns.
New ion-based cooling strategy emerges
Now, researchers at The University of Osaka have developed a strategy to enhance cooling by driving the flow of ions through nanoscale channels. This ionothermoelectric strategy is analogous to the Peltier technique, in which passing an electric current through a material results in heating or cooling. This compelling invention is published in ACS Nano.
“We fabricated a nanosized pore in a semiconductor membrane and surrounded the nanopore with a ‘gate,’ in the form of a nanowire. Applying a voltage to the gate induced the flow of ions through the nanopore,” explains lead author, Makusu Tsutsui. “Varying the voltage modulated the surface charge of the nanopore.”
How voltage controls heating and cooling
A negative applied voltage resulted in a negatively charged nanopore that was only permeable to positively charged ions, or cations. Consequently, each ion drags a certain quantity of heat along with its charge. The team created a concentration gradient in saltwater around the nanopore to drive cation transport in one direction, effectively pumping heat out of the nanopore. Reversing the applied voltage made the nanopore surface positive and permeable only to negative ions, or anions, therefore switching the system from cooling to heating.
“We placed a nanoscale thermocouple next to the holes within the materials—or nanopores—to map temperature changes driven by the voltage-induced ion transport,” says senior author, Tomoji Kawai. “Switching from heating to cooling resulted in temperature drops of over 2 K. We found that the ionic heat transfer depended on the input power as well as the ion species used.”
Potential impact on chip technology
Solid-state nanopores are fully compatible with semiconductor fabrication technologies. Thus, implementing the ionic refrigeration strategy developed at The University of Osaka could increase the capability of next-generation semiconductor chips. Alongside improving capability potential, it is also hoped that these advances in thermal control may also be able to ease environmental concerns.
More information: Makusu Tsutsui et al, Gate-Tunable Ionothermoelectric Cooling in a Solid-State Nanopore, ACS Nano (2025). DOI: 10.1021/acsnano.5c13339
Journal information: ACS Nano
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