For those who need to learn a person’s blood type quickly, there’s a new device that will literally spell it out for them on paper.
The blood types are common knowledge: A+, AB-, O+, etc. As Bethany Halford writes in Chemical & Engineering News, Australian researchers have invented a method that makes these letters and symbols appear on paper — depending on what the specific type is — within a minute. She explains:
The presence or absence of certain antigens on red blood cells determines a person’s blood type. Specific antibodies will react with these antigens and make the red blood cells clump. Researchers led by Wei Shen, of Australia’s Monash University, use an ink-jet printer to apply these antibodies in the shapes of letters A, B, and X as well as a vertical line onto postage-stamp-sized pieces of paper towel. O and rhesus-negative blood types don’t have antigens that react with these antibodies, so the researchers preprint an O in the same spot as the X and a horizontal line intersecting the vertical line on the paper in red waterproof ink.
Someone needing to know a person’s blood type puts a few drops of the person’s blood on the paper and washes it with saline. In about a minute, the letters of the blood type appear. If the blood is type A-positive, antigens will react with antibodies on the A printed on the paper to produce a clump of red blood cells in that letter’s shape and with antibodies in a vertical line to complete a “+” sign.
Antigens also will react with antibodies to form a red X over the preprinted O, to indicate that the blood type is not O. For O-negative blood, antibodies would not react with antigens, leaving the preprinted paper to read “O” above a “-” sign.
Shen got the idea after seeing the film adaptation of J. K. Rowling’s book, Harry Potter and the Chamber of Secrets, in which questions written into a magical diary are answered by the diary in writing. Shen wondered whether technology could be developed if someone wrote on paper, “What’s my blood type?”
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.