While using magnets to make objects levitate isn't anything new, scientists have gained enough control over magnetic forces to where they can now make single living cells levitate.

Previously, scientists were able to levitate things like frogs and mice, however, they lacked the control needed to levitate smaller objects.

"Everything has its own magnetic blueprint," said a member of the team at Stanford University, Utkan Demirci, in an interview with New Scientist. "We started thinking about scaling it all the way down to a single cell."

The report showed that cells are first soaked in a magnetic solution before they are placed between two magnets. The cells then levitate higher than the lower magnet, with height being determined by density — the more mass that they have, the lower they sit. The density of the cell is an important factor in determining what kind of cell it is. With six types of cancer cells in the mix, different types separated into different layers. For example, there was a layer of lung cancer cells, a layer of breast cancer cells and so on due to the fact that the cells had different masses.

Not only that, but they also saw single cells die, with the density of the cells changing in the process. Breast cancer cells, for example, died when put in an acid bath, while yeast cells died with antifungals. Understanding how different cells react to different situations could be key in testing and implementing new drugs and diagnosing different diseases.

Of course, the technique, like any other, also comes with weaknesses. For example, the fact that magnets are used in the levitation process could possibly change properties of certain elements in the cell. Not only that, but the team is still testing to ensure that the magnetic fluid itself does not change the density of cells. Despite this, the fact that the new technique can process a number of cells at the same time is helpful, and it will make the technique useful for picking out rare cells needed in the diagnosis of a disease.

"The nice thing about mag lev is it's pretty simple to do," said George Whitesides from Harvard University, also in an interview with New Scientist. Whitesides was behind a lot of the magnetic levitation technology being used. "Now what has to be done is the hard work that comes with any new analytical method."

The fact that the team is able to sort cells by mass certainly shows that mass is a useful thing to look at when diagnosing different diseases.