May 25, 2019 | Updated: 10:06 PM EDT

Light-activated micro pump can move fluids in any direction

Mar 16, 2019 02:04 PM EDT

(Photo : pixabay)

The work is described in the Proceedings of the National Academy of Sciences.

In this work using a plasmonic quartz plate added with gold atoms, the researchers showed the ability to move liquids by using a laser to produce an ultrasonic wave.

"We can use the laser to make liquids move in any direction," said Jiming Bao, associate professor of electrical and computer engineering at the University of Houston and lead author on the paper.

The work is based on a optofluidics principle that was discovered by Bao's lab and was reported back in 2017. That work explained how a laser could be used to activate a stream of liquid, coupling photoacoustics with acoustic streaming.

The latest work involved fabricating a quartz substrate placed with ten thousand trillion atoms,or 1016 gold atoms, per square centimeter and testing whether a laser pulse could create an ultrasonic wave that is capable of creating a liquid stream. The quartz plate is about the size of a fingernail, and it was added with gold nanoparticles; when a pulsed laser hits the plate, the gold nanoparticles produce an ultrasonic wave, which then drives the fluid through acoustic streaming.

"This new micropump is based on a newly discovered principle of photoacoustic laser streaming and is simply made of an Au [gold] implanted plasmonic quartz plate," the researchers wrote. "Under a pulsed laser excitation, any point on the plate can generate a directional long-lasting ultrasound wave which drives the fluid via acoustic streaming."

The work could have some implications, from drug delivery and biomedical devices to optofluidic and microfluidic research. Wei-Kan Chu, a physicist and project leader at the Texas Center for Superconductivity at UH, said the true value isn't yet known. "We would like to better understand the mechanisms of this, and that could open up something beyond our imagination."

The device was developed in Chu's lab; he is a co-author, along with Njumbe Epie, Xiaonan Shan and Dong Liu, all of UH; Shuai Yue, Feng Lin and Zhiming Wang of the University of Electronic Science and Technology of China; Qiuhui Zhang of Henan University of Engineering; and Suchuan Dong of Purdue University.

The nanoparticles offer a number of targets for the laser that is almost limitless, which can be aimed far better than a mechanical micropump, Bao said.

"The mechanisms of how and why this works are not yet very clear," Chu said. "We need to understand the science better in order to develop the potential of its unforeseeable applications."

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