The movement of fluids through small capillaries and channels is crucial for processes ranging from blood flow through the brain to power generation and electronic cooling systems, but that movement often stops when the channel is smaller than 10 nanometers.
engineer have reported a new understanding of the process and why some fluids stagnate in these tiny channels, as well as a new way to stimulate the fluid flow by using a small increase in temperature or voltage to promote mass and ion transport.
the movement of fluids with lower surface tension, which allows the bonds between molecules to break apart when forced into narrow channels, stopping the process of fluid transport, known as capillary wicking.
But differences in the surface tension of some fluids causes the wicking process—and therefore, the movement of the fluid—to stop when those channels are smaller than 10 nanometers, he said. The researchers reported that it is possible to prompt continued flow by manipulating the surface tension through small stimuli, such as raising the temperature or using a small amount of voltage.
"The surface tension can be changed through different variables," he said. "The simplest one is temperature. If you change temperature of the fluid, you can activate this fluid flow again." The process can be fine-tuned to move the fluid, or just specific ions within it, offering promise for more sophisticated work at nanoscale.
10nm 미만의 channel에서 low surface tension을 가진 liquid는 stagnation되는 경우가 있다고 한다.
temperature나 voltage를 가해서 surface tenstion을 바꿔 흐르게 했다고 한다. control을 잘하면 certain ion만 통과할 수 있다는데 잘은 모르겠다
reference
Masoumeh Nazari et al. Surface Tension Nanogates for Controlled Ion Transport, ACS Applied Nano Materials (2020). DOI: 10.1021/acsanm.0c01304