Sometimes a story comes along that is a combination of ridiculousness and brilliance. In medical scenarios centrifuges are commonly used for the separation of blood samples. These aren’t the titanic machines used for uranium purifying but they are still quite expensive to purchase. This is why this invention is astonishing me so much. By copying the design of an ancient spinning toy that children were playing with 4000 years ago a centrifuge has been created that only costs 20 cents (about 12 pence), weighs 2 grams and can perform 125,000 revolution per minute with centrifugal force approaching 30000 times gravity. The most incredible thing is that the centrifuge is made of paper.
The way it works is by attaching the capillary tube containing whatever liquid is due to be spun in-between two paper disks. These disks have two holes near their centre through which two wound strings are threaded. By pulling these strings taught the disks are allowed to spin and then pass the neutral point a twist themselves up the other way only to become wound once again. It personally reminds me of playground swings when they became spun. This centrifuge, called the paperfuge, was shown to be able to separate plasma from blood in less than 90 seconds and could isolate any micro-organisms causing malaria in about 15 minutes. It is predicted that when perfected the paperfuge could spin at a million times a minute and be used to separate almost anything a normal medical centrifuge could do. The main problems are that the mechanism can only take small samples and the process of winding the string can be very time consuming. This is possibility the purest form of discovery, taking a toy constructed ,many millennia ago and successfully converting it into a practical application. The fact that the disks could be constructed from anything from polymers to metals means that this device can certainly be improved and with development will no doubt revolutionise global medical science.
Paper links: Hand-powered ultralow-cost paper centrifuge