Tag Archives: Tony Jun Huang

Controlling the tiniest particles with sound-induced electrical fields

I find the use of sound as a research tool in this June 23, 2021 news item on ScienceDaily to be fascinating,

Engineers at Duke University [North Carolina, USL] have devised a system for manipulating particles approaching the miniscule 2.5 nanometer diameter of DNA using sound-induced electric fields. Dubbed “acoustoelectronic nanotweezers,” the approach provides a label-free, dynamically controllable method of moving and trapping nanoparticles over a large area. The technology holds promise for applications in the fields ranging from condensed matter physics to biomedicine.

A June 22, 2021 Duke University news release (also on EurekAlert) by Ben Kingery, which originated the news item, explains the interest in precise control and the use of sound in more detail,

Precisely controlling nanoparticles is a crucial ability for many emerging technologies. For example, separating exosomes and other tiny biological molecules from blood could lead to new types of diagnostic tests for the early detection of tumors and neurodegenerative diseases. Placing engineered nanoparticles in a specific pattern before fixing them in place can help create new types of materials with highly tunable properties.

For more than a decade, Tony Jun Huang, the William Bevan Distinguished Professor of Mechanical Engineering and Materials Science at Duke, has pursued acoustic tweezer systems that use sound waves to manipulate particles. However, it becomes difficult to push things around with sound when their profile drops below that of some of the smallest viruses.

“Although we’re still fundamentally using sound, our acoustoelectronic nanotweezers use a very different mechanism than these previous technologies,” said Joseph Rufo, a graduate student working in Huang’s laboratory. “Now we’re not only exploiting acoustic waves, but electric fields with the properties of acoustic waves.”

Instead of using sound waves to directly move the nanoparticles, Huang, Rufo and Peiran Zhang, a postdoc in Huang’s laboratory, use sound waves to create electric fields that provide the push. The new acoustoelectronic tweezer approach works by placing a piezoelectric substrate–a thin material that creates electricity in response to mechanical stress–beneath a small chamber filled with liquid. Four transducers are aligned on the chamber’s sides, which send sound waves into the piezoelectric substrate.

These sound waves bounce around and interact with one another to create a stable pattern. And because the sound waves are creating stresses within the piezoelectric substrate, they also create electrical fields. These couple with the acoustic waves in a way that creates electric field patterns within the chamber above.

“The vibrations of the sound waves also make the electric field dynamically alternate between positive and negative charges,” said Zhang. “This alternating electric field polarizes the nanoparticles in liquid, which serves as a handle to manipulate them.”

The result is a mechanism that mixes some of the strengths of other nanoparticle manipulators. Because the acoustoelectronic nanotweezers induce an electromagnetic response in the nanomaterials, the nanoparticles do not need to be conductive on their own or tagged with any sort of modifier. And because the patterns are created with sound waves, their positions and properties can be quickly and easily modified to create a variety of options.

In the prototype, the researchers show nanoparticles placed into striped and checkerboard patterns. They even push individual particles around in an arbitrary manner dynamically, spelling out letters such as D, U, K and E [emphasis mine]. The researchers then demonstrate that these aligned nano-patterns can be transferred onto dry films using delicate nanoparticles such as carbon nanotubes, 3.5-nanometer proteins and 1.4-nanometer dextran often used in biomedical research. And they show that all of this can be accomplished on a working area that is tens to hundreds of times larger than current state-of-the-art nanotweezing technologies [emphasis mine].

Nanotweezing technologies? This concept is new to me.How will I work it into my next conversation?

As for spelling out D, U, K, and E, that brings to mind Don Eigler (from his Wikipedia entry),

In 1989, Eigler was the first to use a scanning tunneling microscope tip to arrange individual atoms on a surface, famously spelling out the letters “IBM” with 35 xenon atoms.

Perhaps the Duke University researchers intended an ‘hommage’? or ‘tip of the hat’?

Here’s a link to and a citation for the paper,

Acoustoelectronic nanotweezers enable dynamic and large-scale control of nanomaterials by Peiran Zhang, Joseph Rufo, Chuyi Chen, Jianping Xia, Zhenhua Tian, Liying Zhang, Nanjing Hao, Zhanwei Zhong, Yuyang Gu, Krishnendu Chakrabarty & Tony Jun Huang. Nature Communications volume 12, Article number: 3844 (2021) DOI: https://doi.org/10.1038/s41467-021-24101-z Published 22 June 2021

This paper is open access.

Acoustofluidics and lab-on-a-chip for asthma and tuberculosis diagnostics

This is my first exposure to acoustofluidics (although it’s been around for a few years) and it concerns lab-on-a-chip diagnostics for asthma and tuberculosis. From an Aug. 3, 2015 news item on Azonano,

A device to mix liquids utilizing ultrasonics is the first and most difficult component in a miniaturized system for low-cost analysis of sputum from patients with pulmonary diseases such as tuberculosis and asthma.

The device, developed by engineers at Penn State in collaboration with researchers at the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health, and the Washington University School of Medicine, will benefit patients in the U.S., where 12 percent of the population, or around 19 million people, have asthma, and in undeveloped regions where TB is still a widespread and often deadly contagion.

“To develop more accurate diagnosis and treatment approaches for patients with pulmonary diseases, we have to analyze sample cells directly from the lungs rather than by drawing blood,” said Tony Jun Huang, professor of engineering science and mechanics at Penn State and the inventor, with his group, of this and other acoustofluidic devices based on ultrasonic waves. “For instance, different drugs are used to treat different types of asthma patients. If you know what a person’s immunophenotype is, you can provide personalized medicine for their particular disease.

A July 29, 2015 Pennsylvania State University news release, which originated the news item, describes the disadvantages of the current sputum analyses techniques and explains how this new technique in an improvement,

There are several issues with the current standard method for sputum analysis. The first is that human specimens can be contagious, and sputum analysis requires handling of specimens in several discrete machines. With a lab on a chip device, all biospecimens are safely contained in a single disposable component.

Another issue is the sample size required for analysis in the current system, which is often larger than a person can easily produce. The acoustofluidic sputum liquefier created by Huang’s group requires 100 times less sample while still providing accuracy equivalent to the standard system.

A further issue is that current systems are difficult to use and require trained operators. With the lab on a chip system, a nurse can operate the device with a touch of a few buttons and get a read out, or the patient could even operate the device at home. In addition, the disposable portion of the device should cost less than a dollar to manufacture.

Po-Hsun Huang, a graduate student in the Huang group and the first author on the recent paper describing the device in the Royal Society of Chemistry journal Lab on a Chip, said “This will offer quick analysis of samples without having to send them out to a centralized lab. While I have been working on the liquefaction component of the device, my lab mates are working on the flow cytometry analysis component, which should be ready soon. This is the first on-chip sputum liquefier anyone has developed.”

Stewart J. Levine, a Senior Investigator and Chief of the Laboratory of Asthma and Lung Inflammation in the Division of Intramural Research at NHLBI, said “This on-chip sputum liquefier is a significant advance regarding our goal of developing a point-of-care diagnostic device that will determine the type of inflammation present in the lungs of asthmatics. This will allow health care providers to individualize asthma treatments for each patient and advance the goal of bringing precision medicine into clinical practice.”

Here’s a link to and a citation for the paper,

An acoustofluidic sputum liquefier by Po-Hsun Huang, Liqiang Ren, Nitesh Nama, Sixing Li, Peng Li, Xianglan Yao, Rosemarie A. Cuento, Cheng-Hsin Wei, Yuchao Chen, Yuliang Xie, Ahmad Ahsan Nawaz, Yael G. Alevy, Michael J. Holtzman, J. Philip McCoy, Stewart J. Levine, and  Tony Jun Huang. Lab Chip, 2015,15, 3125-3131 DOI: 10.1039/C5LC00539F

First published online 17 Jun 2015

This is an open access paper but you do need to register for a free (British) Royal Society of Chemistry publishing personal account.