Startup Idea : Blood Discovery Apparatus ( B.O.A )

This is more of a hit, if the engineer fragment of the idea comes together. This is more of a product for a fast telling of someone's blood type. I know, there is already a way to find your blood type. But not in the way it is efficient and fast for Doctors and Nurses. When a patient comes in with, let's say, a gun shot wound; the first thing or one of the first things to do is stabilize and give a blood transfusion. Hopefully, haven't lost you yet. The nurse doesn't know the patient's blood type so the first thing they do is give 0 negative.. As blood type has to be compatible with each other. After the initial transfusion of O negative, then someone is sent to run tests to find blood type. There is a blood shortage. And the B.O.A would be an answer to a few issues. The B.O.A is a small handheld machinery, that i'd like to be as small as a common day cellphone. Where as a simple prick of a finger, or where ever will yield results where a nurse can get the patient's blood matched correctly and efficiently. Blood has different price points that hospitals much abide by. B.O.A is cost effective, as price point vary by type. And less work for the nurses to find the blood type.