Given that one only needs to recirculate 5-7% of the blood and expose it to UV C, could we not shrink this age-old device into something portable? I don't know

Given that one only needs to recirculate 5-7% of the blood and expose it to UV C, could we not shrink this age-old device into something portable? I don't know anything about phlebotomy or the implications of liquid pressure in the body, but it seems like if you can administer a syringe you can draw blood, UV it, and put it back in as well.