This 13-year-old came up with a brilliant way to stop people from driving drunk or high

Drunk Driver Caught After Trying to Drive on the Pavement
Drunk Driver Caught After Trying to Drive on the Pavement

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 in 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.

Here's a creepy gif of the pupillary reflex in action:


Krishna Reddy

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

It works like this: The flashlight is held up to the eye, and the toilet roll directs the light onto the pupil. Then, the digital camera takes video of the pupil as it contracts. Using a software program Reddy wrote, the device (and a computer) measures the constriction of the pupil when the light is shone on it.

So far, it can be used to tell if someone has been drinking, smoking marijuana, or if they've used certain painkillers, sleep aids, or amphetamines. Because the pupillary reflex happens on the scale of millimeters and milliseconds, the device is far better than the naked eye at detecting a drunk or impaired driver, Reddy explains in a short video about the project.

The hope is that this device could detect when a driver's reflexes are impaired, and ultimately cut down on lethal traffic crashes. At least, until we all have driverless cars, that is.

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Originally published