About the size of a business card, the device uses technology that the team initially developed to monitor T cell counts in HIV patients. An organic polymer sandwiched between two glass slides is carved with 16 channels, which are coated with an antibody that binds specifically to neutrophils. The antibodies selectively capture the cells as blood flows through the device. The capture process takes only about five minutes, and is simple enough to be done by a nurse or doctor at the patient's bedside. "We engineered it to be as simple as possible," says Kotz. Scientists then add different chemicals to the chip to isolate DNA, proteins, or other molecules from the cells. These molecules are then sent for further analysis.

A quick capture procedure is especially important for neutrophils. Researchers want to study the genes and proteins that become active in the cells after injury, and a lengthy or arduous isolation process can artificially activate some molecules, or kill the cells altogether. Kotz says that the new technology was much more effective than traditional methods at generating adequate amounts of RNA for later analysis.

Kotz and his team are developing similar chips to capture other types of immune cells. They have already isolated and analyzed lymphocytes, which include the immune cells that make antibodies against bacteria, and are now working on monocytes, another type of immune cell. The ability to separate and study the different immune cells individually will give researchers a better idea of the role each cell plays in the immune response, and how different cells might be targeted if something goes wrong.