Researchers at an Australian university have developed the first dipstick-type test to determine blood type. The test involves putting a drop of blood onto a thin piece of paper that has been specially printed with antibodies; as the blood seeps into different parts of the paper, the blood type is revealed. The researchers say the test, which costs pennies, could improve medical treatments in the developing world.

Blood typing is one of the most basic medical tests, but it currently requires delicate analysis with microfluidic or optical devices and costs hundreds of dollars per test. People have one of four main blood types, based on antigens on the red blood cells: A, B, AB, and O. Knowledge of blood type is critical to successful blood transfusions, which save millions of lives each year worldwide, and using the wrong type of blood can trigger a fatal reaction.

The Australian research team is comprised of engineers and materials scientists who work on printing different biological substances to create bioactive paper. This involves a modified ink-jet printer, in which the ink is replaced by enzymes or antibodies. They were experimenting with different substances when they noticed something happening to the paper after printing with blood antibodies. "When you put a drop of blood on a Kleenex, it goes everywhere," says Gil Garnier , a professor of chemical engineering at Monash University, who led the work. "But if it agglutinates, it stays in one place." Agglutination, or thickening, happens when a specific blood type meets a specific antibody.

With this knowledge in hand, the team developed a piece of paper with three arms--each printed with a different antibody that matches the antigens on red blood cells. A drop of blood placed in the center of the paper moves along each arm, but it will be stopped if it meets a matching antibody, revealing the blood type. The test has demonstrated the same accuracy as current lab-based blood typing, according to Garnier. In addition, the whole process costs less than 10 U.S. cents per test and requires only a drop of blood. Garnier says that the bioactive paper could be a useful platform for other types of blood tests, including those for tuberculosis, anemia, and diabetes. The research was published in the journal Analytical Chemistry.

The team recognizes some difficulties of putting their test into action, however. Many places that need such cheap testing are in very hot climates, so the paper needs to be robust enough to be exposed to high temperatures--and that still needs some work, according to Garnier.

In addition, the paper cannot test for everything. "[This test] is only part of the process in preparing to transfuse someone," says Robert Richard, associate professor of medicine in the Hemology Division at the University of Washington. "It doesn't address the need to cross-match the units to control against a hemolytic reaction from a non-ABO, non-Rh antigen incompatibility."

Nonetheless, Garnier says, a cheap, portable paper test could help deliver "low-cost and accessible information to empower people, especially in developing countries."