A Fast Cell Sorter Shrinks to Cell Phone Size

Commercial fluorescence activated cell sorters have been highly successful in the past 40 years at rapidly and accurately aiding medical diagnosis and biological studies, but they are bulky and too expensive ($200,000 -$1,000,000) for many labs or doctors’ offices. Most significantly, these types of cell sorters can present biohazard concerns for operators and may damage cells or alter their properties, making them unfit for further study. To address these issues, researchers at Penn State have developed a new lab-on-a-chip cell sorting device based on acoustic waves.

In the cover story in the current issue of the British journal Lab on a Chip, researchers in the Department of Engineering Science and Mechanics at Penn State, along with Ascent Bio-Nano Technologies and the National Heart, Lung, and Blood Institute, a part of the National Institutes of Health, describe an acoustic cell sorter capable of the kind of high sorting throughput necessary to compete with commercial fluorescence activated cell sorters.  
“The current benchtop cell sorters are too expensive, too un-safe, and too high-maintenance. More importantly, they have very low biocompatibility. The cell-sorting process can reduce cell viability and functions by 30−99 percent for many fragile or sensitive cells such as neurons, stem cells, liver cells and sperm cells,” said Tony Jun Huang, Penn State professor of engineering science and mechanics and the paper’s corresponding author. “We are developing an acoustic cell sorter that has the potential to address all these problems.”  

The Penn State system can sort about 3,000 cells per second, with the potential to sort more than 13,000 cells per second. The speed is generated by using focused interdigital transducers to create standing surface acoustic waves (SSAWs). When the waves are not focused, the acoustic field spreads out, slowing the sorting process. The narrow field allows the sorting to take place at high speed while gently manipulating individual cells.
Because the device is built on a lab-on-a chip system, it is both compact and inexpensive – about the size and cost of a cell phone in its current configuration. With the addition of optics, the device would still be only as large as a book. The acoustic cell sorter was fabricated in Penn State’s Nanofabrication Laboratory using standard lithography techniques.

“To the best of our knowledge, our device demonstrates the fastest operation time among all existing acoustic cell sorters,” said Liqiang Ren, a graduate student in Huang’s group and the paper’s lead author. 
In future work, the researchers plan to integrate their acoustic cell-sorting unit with an optical cell-detecting unit with the goal of increasing throughput to 10,000 events per second.

Additional authors on the paper titled “A high-throughput acoustic cell sorter” are Yuchao Chen, Peng Li, Zhangming Mao, Po-Hsun Huang, Joseph Rufo and Feng Guo, all of Penn State, Lin Wang of Ascent Bio-Nano Technologies and Philip McCoy and Stewart J. Levine, National Heart, Lung, and Blood Institute. Funding was provided by the National Institutes of Health, the National Science Foundation, and the Penn State Center for Nanoscale Science. Portions of the work were performed at the Penn State Nanofabrication Laboratory, a node of the NSF-funded National Nanotechnology Infrastructure Network.