Researchers from three universities have successfully managed to use sound waves to manipulate cells in three dimensions with “acoustic tweezers” opening a door to the potential for 3-D printing of cell structures that could be used for tissue engineering among other uses.

"Acoustic Tweezers" Could Provide Breakthrough In Tissue Engineering

What are these “acoustic tweezers?”

Researchers and engineers have struggled to design tissue implants that allow cells to remain viable and functional, but this might have changed according to paper published in this week’s Proceedings of the National Academy of Sciences.

Engineers at the Massachusetts Institute of Technology (MIT), Penn State University, and Carnegie Mellon University will be applying for a patent for a technique they developed that allows them to precisely move cells where they want them in three dimensions through the use of sound waves or “acoustic tweezers.”

“The results presented in this paper provide a unique pathway to manipulate biological cells accurately and in three dimensions, without the need for any invasive contact, tagging, or biochemical labeling,” says Subra Suresh, president of Carnegie Mellon and former dean of engineering at MIT. “This approach could lead to new possibilities for research and applications in such areas as regenerative medicine, neuroscience, tissue engineering, biomanufacturing, and cancer metastasis.”

Suresh (Carnegie Mellon) , Ming Dao, a principal research scientist in MIT’s Department of Materials Science and Engineering, and Tony Jun Huang, a professor of engineering science and mechanics at Penn State, are the senior authors of the paper published this week. The lead author is a graduate student at Penn State University, Feng Guo. The team also included eight additional researchers from Penn State.

Acoustic Tweezers in 3-D

The researchers prior to this breakthrough in three dimensions had designed a microfluidic device that allowed them to manipulate cells in two dimensions. The first device sent to acoustic standing waves of a constant height toward a group of cells. When the two waves meet, the combine to form a “pressure node” that can then hunt for and trap a single cell within the node. Once trapped, the researchers alter the wavelength of the phase allowing them to move the node and, more importantly, move the cell trapped inside.

However, according to this paper, the researchers added a third dimension of cell manipulation by altering the waves’ power, or the rate at which the sound energy is transmitted from its source. By raising the rate the researchers could then lift the cells from the surface in a type of “acoustic levitation” and put them wherever they wished according to Dao.

“We now have a good idea of what to expect and how to control the 3-D positioning of the acoustic waves and the pressure nodes, enabling validation of the method as well as system optimization,” Dao says.

The newly developed technique could be a tremendous interest from biologists to bioengineers. This innovative approach to using acoustic energy to manipulate particles and single cells in 3-D in fluids protects the cells and is wholly noninvasive while maintaining the cells viability.

“The results presented in this paper provide a unique pathway to manipulate biological cells, accurately and in three dimensions, without the need for any invasive contact, tagging, or biochemical labeling,” said Subra Suresh. “This approach could lead to new possibilities for research and applications in such areas as regenerative medicine, neuroscience, tissue engineering, biomanufacturing, and cancer metastasis.”