An illustration of the surface acoustic wave generators, with the generated 3-D trapping nodes. The inset indicates a single particle within a 3-D trapping node, which can be manipulated independently along x, y, or z axes. (Image courtesy of MIT.)

A team of engineers at MIT, Penn State University and Carnegie Mellon University has developed a method for 3-D cell manipulation by coupling acoustics with micro-fluidics. According to the researchers, their “acoustic tweezers” could enable 3D printed cell structures for tissue engineering and other applications.

Using Acoustics for 3D Cell Manipulation

Building on micro-fluidic devices for 2-D cell manipulation, the new device adds third dimension control through acoustics.

Acoustic tweezers.

The researchers created “pressure nodes” by generating two acoustic standing waves. Cells are trapped within this node, which can be moved by changing wavelength and phase. Once the cells have trapped in the horizontal plane, the acoustic waves’ power can be used to create vertical movement.

The research team also developed equations which can accurately predict these changes for optimal cell manipulation control.

The researchers used polystyrene particles and mouse fibroblast cells to test the device. The cells were moved one at a time into specific positions on a surface, creating patterns and stacks. The research team also successfully separated cancer cells from healthy cells with this method.

“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,” said Ming Dao, a research scientist in MIT’s department of materials science and engineering.

Healthcare Implications of Acoustic Tweezers

Health care advancements often fuel these kinds of experiments and this new method could potentially lead to new techniques for tissue implants and new methods of treating disease.

The researchers are confident that this non-invasive approach can bring about benefits in the medical field.

“The results 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, 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 added.

For more information, see the paper describing the device published in the Proceedings of the National Academy of Sciences.