The students, Chin Jung Cheng, Charlie Matlack, Penny Huang, and Jacqueline Linnes, took on a challenge put forth by the Bolivia-based nonprofit group, to develop a method of providing clean drinking water to those who currently lack it.

The contest was promoted by , and sponsored by the nonprofit . The challenge in question involves a process known as SODIS (Solar Disinfection of water in plastic bottles), a process that removes 99.9 percent of bacteria and viruses.

For SODIS, all you have to do is fill a clear plastic bottle with water and leave it in the sun for a period time; the sun's heat and ultraviolet rays will kill anything inside. Unfortunately, until now, there was no simple way of knowing when the water was purified. The SODIS device is very simple, and uses parts from a keychain that blinks when exposed to light. The device is attached to a water bottle, and it monitors the clarity inside the bottle, blinking when the light is obstructed by particles. When there are no longer particles floating around, the light stops blinking and you have 99.9 percent clean drinking water.

The simple device costs only $3.40, and with mass production and bulk purchases the price should drop even further. The provided the students with a $40,000 prize. Let's hope the students use it to continue their goodwill.

[Via / Photo: on Flickr; used under .