Researchers in Australia say they've successfully engineered the first dipstick-like blood-type test. By placing a drop of blood on a thin piece of paper that has been specially printed with antibodies, the blood's type is revealed based on which parts of the paper it seeps into.
The team, led by chemical engineering professor Gil Garnier at Monash University in Victoria, estimates the cost of the test at 10 cents. (By comparison, simple blood-type tests typically cost at least $15.)
The main grouping of blood types is ABO, and results in type A, type B, type AB, or type O (O indicating zero or absence of antigens). A separate grouping system, Rh, essentially qualifies blood types as positive or negative. The vast majority of people, then, have a blood type that can be characterized as A positive or A negative, B positive or B negative, AB positive or AB negative, and O positive or O negative.
Knowing one's blood type is crucial in the event that a blood transfusion is necessary, as complications such as shock and renal failure can occur between certain incompatible blood types. Someone whose blood type is O negative is considered a universal donor, while someone who is AB positive is a universal recipient.
The engineers and material scientists had actually been experimenting with different substances when they noticed something strange. "When you put a drop of blood on a Kleenex, it goes everywhere," Garnier told MIT's Technology Review. "But if it agglutinates [thickens], it stays in one place."
So they built a piece of paper with three arms, each printed (using enzymes or antibodies instead of ink in a modified ink-jet printer) with a different antibody to match the antigens on red blood cells--one for A, one for B, one for Rh.
The drop of blood placed in the center of the arms moves along each arm and stops if it hit a matching antibody. If the blood stops on the A arm but nowhere else, for instance, its type is A negative. If it stops on A and Rh, it is A positive.
The blood type that stops on all three arms, then, is AB positive, indicating a universal recipient, while the blood that doesn't stop at all is O negative and belongs to a universal donor.
The team's work, detailed in the journal Analytical Chemistry, isn't done yet. First, the very thin paper must be strong enough to withstand exposure to high temperatures so that these tests can be used in the earth's hottest climates.
Second, identifying one's basic blood type cannot in and of itself prepare someone for a successful blood transfusion, as many other sub-types can still interact. It's "only part of the process," says Robert Richard, associate professor of medicine at the University of Washington's Hemology Division. "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."
But at the very least, identifying at just 10 cents a test which people in a rural and/or poor community are universal donors and which are universal recipients could help save lives.