Some questions about the straws:
1. How do you make sure the Health Monitor has enough straws? It means you need staff to check and refill the straws every few days if the straws are stored within the machine. Multiple times a day if they are in a dispenser, because kids will take them all. Have you taken into account the costs of refilling straws?
2. If you store the straws inside the Health Monitor, you need to design and construct a dispenser mechanism. Have you take into account those costs?
3. Is it possible for the straws to release particles that influence the measurements?
Well, the check could be made electonical if the straws are kept inside of an dispenser mechanism. Some system which checks how many straws are left and send an signal if there are not many left.