[skwb]

The problem is that physiologically the blood you get for chem-10 (stuff like Sodium/Potassium) are completely invalid using finger prick (you rupture too many cells and they leak out their intracellular fluids, messing with your results). This is basic pathology 101 and completely negates any way to work around this fundamental problem. It goes back to the example they give at the beginning where she had the idea of an antibiotic patch, but you need IV antibiotics for delivery.