Contactless diamagnetic trapping of living cells onto a micromagnet array.

This paper focuses on the application of magnetophoresis to a new cell patterning method. The principle was demonstrated by using a CoPt micromagnet array, producing regularly spaced magnetic traps where cells were confined without any contact under the effect of negative magnetophoresis. To obtain this effect, yeast cells (Saccharomyces cerevisiae), which are diamagnetic, were placed in an aqueous solution enriched in paramagnetic ions. Unlabeled (non-magnetic) cell manipulation by magnetophoresis requires the production of high magnetic field gradients, ensuring significant forces. Therefore, micromagnets are particularly interesting for our application, since the field gradient increases as magnet dimensions are reduced.