Washington: An Indian-origin scientist has developed a tiny chemistry set which only costs USD 5 and can be used to test water quality and provide affordable medical diagnostic tests in the developing world. Manu Prakash, an assistant professor of bioengineering at Stanford, has won USD 50,000 to further develop his prototype into a low-cost product, which he thinks can have widespread use both in the developing world and as a creative toy for kids. The idea for the device came to Prakash from a toy music box. The box used a tiny hand crank to pull a paper ribbon through a set of pins on concentric disks. When one of the pins hit a hole in the paper, the disk and pin rotated, causing another pin to pluck a metal strip to make a sound.

Prakash got the idea that the rotating pins could also be used to pump fluids through tiny channels or to control valves and droplet generators in a programmable fashion. After talking to George Korir, student, Prakash started working with him on a way of pairing the hand-cranked toy with a small silicon chip containing tiny channels for manipulating fluids. Like the music box, the prototype chemistry set includes a hand-cranked wheel and paper tape with periodic holes punched by the user. When a pin encounters a hole in the tape it flips and activates a pump that releases a single drop from a channel.

In the simplest design, 15 independent pumps, valves and droplet generators can all be controlled simultaneously. The portable, programmable chemistry kit could be used around the world to test water quality, provide affordable medical diagnostic tests, assess soil chemistry for agriculture or serve as a snake bite venom test kit. It could even be used in modern labs to carry out experiments on a very small scale. Prakash has also developed a low-cost microscope called Foldscope that can be folded like origami out of paper.