Indian-origin teen's device can curb drunk driving

Drunk-driving crashes killed more than 10,000 people in the US in 2013 -- about 30 people every day. Krishna Reddy wants to change that.

The 13-year-old from Wichita Falls, Texas, invented a device that can tell when a driver has consumed alcohol or used other drugs based on how dilated his or her pupils are.

Reddy is one of 10 finalists of the Discovery Education 3M Young Scientist Challenge, an annual competition for the title of America's Top Young Scientist and a $25,000 prize. The finals will take place on October 12 and 13.

Reinventing the breathalyzer

Breathalyzers, which measure the alcohol content in a breath sample, can detect when someone has had a drink, but not if they've had other drugs. And they require the driver's consent to work (as opposed to being automatic).

Reddy wanted to create something better.

Our pupils constrict to filter the amount of light that gets into our eyes. When we look into a bright light, our pupils get smaller; when it becomes dark, our pupils dilate, or get bigger. This is known as the pupillary reflex. While certain drugs, like alcohol and opioids, can cause our pupils to constrict, others, like LSD, magic mushrooms, and cocaine, can cause them to dilate.

Taking advantage of this effect, Reddy built a device made of three things: A digital camera, a snakehead flashlight, and a toilet paper roll.