South Korean and American scientists have developed a low-cost biochip that can be used to identify a person's blood group by eye.

Tai Hun Kwon from the Pohang University of Science and Technology led a team of researchers to produce a prototype biochip that they used to determine the blood group of several blood samples. 

The blood group of a sample is found by checking which of several known blood cell and serum types the sample reacts with. Red blood cells can contain either or both A or B antigens, and blood will react with cells containing a different type of antigen. For example, type A blood will react to the B antigens in type B or AB cells, but it will not react with type A cells or type O cells (which contain neither of the antigens). The red blood cells in the sample respond by agglutinating, forming clumps that can be seen by the naked eye in Kwon's device.

At present there are several ways of checking blood groups, but they are all expensive or must be performed manually, said Kwon. The new device is made from injection moulded plastic, which the team hopes will make it suitable for mass production. It only takes three minutes to identify the blood group of a sample, and can work with as little as three microlitres of blood.

Quickly identifying blood groups is important in a wide variety of medical tests, including checking that a blood transfusion or organ donation will not cause a dangerous immune response in the patient.

Kwon says that the biochip could provide a platform for 'developing low-cost disposable plastic labs-on-chips ... for a wide variety of diagnostic examinations.'