Discovery will allow more sophisticated work at nanoscale

July 28, 2020

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.

Researchers led by a University of Houston 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 work, published in ACS Applied Nano Materials, explores 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. The research was also featured on the journal's cover.

Hadi Ghasemi, Cullen Associate Professor of Mechanical Engineering at UH and corresponding author for the paper, said this capillary force drives liquid flow in small channels and is the critical mechanism for mass transport in nature and technology - that is, in situations ranging from blood flow in the human brain to the movement of water and nutrients from soil to plant roots and leaves, as well as in industrial processes.

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.

Ghasemi said raising the temperature even slightly can activate movement by changing surface tension, which they dubbed "nanogates." Depending on the liquid, raising the temperature between 2 degrees Centigrade and 3 degrees C is enough to mobilize the fluid.

"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.

"The surface tension nanogates promise platforms to govern nanoscale functionality of a wide spectrum of systems, and applications can be foreseen in drug delivery, energy conversion, power generation, seawater desalination, and ionic separation," the researchers wrote.
In addition to Ghasemi and first author Masoumeh Nazari, researchers involved with the project include Sina Nazifi, Zixu Huang, Tian Tong and Jiming Bao, all with the University of Houston, and Kausik Das and Habilou Ouro-Koura, both with the University of Maryland Eastern Shore.

Funding for the project came from the Air Force Office of Scientific Research, the National Science Foundation and the U.S. Department of Education.

University of Houston

Related Blood Flow Articles from Brightsurf:

Brain regions with impaired blood flow have higher tau levels
In Alzheimer's disease, impaired blood flow to brain regions coincides with tau protein buildup.

3D ultrasound enables accurate, noninvasive measurements of blood flow
A 3D ultrasound system provides an effective, noninvasive way to estimate blood flow that retains its accuracy across different equipment, operators and facilities, according to a new study.

Blood flow recovers faster than brain in micro strokes
Work by a Rice neurobiologist shows that increased blood flow to the brain is not an accurate indicator of neuronal recovery after a microscopic stroke.

Exercise improves memory, boosts blood flow to brain
Scientists have collected plenty of evidence linking exercise to brain health, with some research suggesting fitness may even improve memory.

3D VR blood flow to improve cardiovascular care
Biomedical engineers are developing a massive fluid dynamics simulator that can model blood flow through the full human arterial system at subcellular resolution.

MRI shows blood flow differs in men and women
Healthy men and women have different blood flow characteristics in their hearts, according to a new study.

Brain blood flow sensor discovery could aid treatments for high blood pressure & dementia
A study led by researchers at UCL has discovered the mechanism that allows the brain to monitor its own blood supply, a finding in rats which may help to find new treatments for human conditions including hypertension (high blood pressure) and dementia.

Blood flow monitor could save lives
A tiny fibre-optic sensor has the potential to save lives in open heart surgery, and even during surgery on pre-term babies.

Changes in blood flow tell heart cells to regenerate
Altered blood flow resulting from heart injury switches on a communication cascade that reprograms heart cells and leads to heart regeneration in zebrafish.

Blood flow command center discovered in the brain
An international team of researchers has discovered a group of cells in the brain that may function as a 'master-controller' for the cardiovascular system, orchestrating the control of blood flow to different parts of the body.

Read More: Blood Flow News and Blood Flow Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to