The new technique should make it much easier for scientists to study what happens when two cells are combined, the study published in the journal Nature Methods suggests.

For example, fusing an adult cell and an embryonic stem cell allows researchers to study the genetic reprogramming that occurs in such hybrids, the study says.

Previously, if scientists wanted to combine two cell types -- for example A and B -- they would end up with many AA and BB pairings, as well as the desired AB match.

They typically trapped cells in tiny cups as they flowed across a chip. Each cup could hold only two cells, but there was no way of controlling whether the cups captured an A and a B, two As or two Bs.

By contrast, the cell-trapping cups developed by the MIT team, headed by electrical engineering and computer science Associate Professor Joel Voldman and biology Professor Rudolf Jaenisch, are arranged strategically to capture and pair up cells of different types, the study says.

The new sorting method increases the rate of successful cell fusion from around 10 percent to about 50 percent and allows for thousands of cell pairings at once.

In addition to helping study stem cell reprogramming, the technique could be used to study interactions between any types of cells.

"It's a very general type of device," Voldman said.