sound waves to classify cells
For research or medical diagnostics, it is often necessary to sort the cells of a fluid in accordance with different parameters. Currently, existing techniques require labeling the cells with chemicals or exposed to mechanical forces that can damage them.
That's why researchers are trying to develop milder methods that best preserve the cells. Using sound waves is an interesting alternative, as Dao Ming, a researcher in the department of materials science and engineering at MIT explains, "the sound pressure is very light and very inferior in terms of resistance and the cell disruption. is a smoother way to remove cells and artificial no need to dial ".
To sort the cells using acoustic waves, scientists first build devices that were issued in two waves on each side of a microchannel. For assembly, the two are combined to form an acoustic standing wave parallel to the direction of the fluid cell surface. Like any standing wave has pressure nodes. When cells are one of them, that are thrust toward the side of the channel. The distance of movement of the cell depends on the cell size and other properties such as compressibility. But this method was ineffective, hence the need for improvements.
Improved efficiency through the inclination of the waves
In an article published in PNAS, the researchers explain that the disadvantage of the method used above was that the cells were not pushed aside in short distances. The new tool developed overcomes this obstacle by the inclination of the acoustic waves with respect to the direction of flow: for example, a cell may find several nodes pressure passes through the channel. Each time, the more pressure guides, from the center, which facilitates the capture of cells of different sizes.
This device significantly enhances the efficiency and sensitivity of acoustic separation techniques: the researchers were able to separate polystyrene beads from 2 to 10 microns with an efficiency of 99%, and the grains of 7.3 and 9.9 microns with a 97% efficiency. They also conducted a computer simulation to predict the trajectory of the cells in the channel based on their characteristics and the angle of the acoustic waves: this allowed them to develop a device capable of separating different types of cells.
Many applications can be envisaged, particularly in the field of diagnosis. Therefore, such a device could detect rare circulating in the blood, which indicate whether a primary cancer generates m. Another possible application: separation of blood cells (red cells, white cells, platelets).
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