Not everyone's blood clots at the same rate. While that might seem like simply an interesting bit of trivia, it's anything but trivial to doctors performing operations or emergency procedures, who need to know what might be required in the way of transfusions or anticoagulant drugs. Now, an optical device can provide them with that information within minutes.

Currently, in order to measure its clotting properties, patients' blood must be subjected to a series of lab tests that can take hours to perform, that require relatively large amounts of blood, or that involve large, expensive machines. The new device, developed by a team at Massachusetts General Hospital, gets much quicker, less costly results, it's about the size of a Kleenex box, and it only requires a few drops.

It utilizes a process known as laser speckle rheology, in which a laser is shined into the liquid, and the patterns of the reflected light are analyzed. In the case of unclotted blood, the freely-moving cells and platelets cause the pattern to fluctuate rapidly. As the cells and platelets start to join and the blood starts to coagulate, however, there's less movement and thus less fluctuations.

Using a miniature high-speed camera, it's possible to monitor the change in the amount of fluctuations over a period of several minutes. That information can be used to deduce both the overall clotting time, and the concentration of fibrinogen (a protein involved in the clotting process) in the blood.

The current prototype must be hooked up to a computer, although the scientists hope to have a self-contained mobile phone-sized device ready for clinical trials within a year.

The research was led by assistant professor Seemantini Nadkarni, and a paper on it was recently published in the journal Biomedical Optics Express.