No one really knows why, but for an open wound, simply applying suction dramatically speeds healing times. (The theory is that the negative pressure draws bacteria out, and encourages circulation.) But for almost everyone, that treatment is out of reach–simply because the systems are expensive–rentals cost at least $100 a day and need to be recharged every six hours. No more. Danielle Zurovcik, a doctoral student at MIT, has created a hand-powered suction-healing system that costs about $3.