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Philip Low almost didn’t meet Stephen Hawking.

Running his own start-up, NeuroVigil, was exhausting for Low and after his speech at the World Science Festival in New York, the last thing he wanted to do was socialize at an event at the Metropolitan Museum of Art — even if Hawking was supposed to be in attendance. As he was packing for his flight home to San Diego in his hotel room, Low suddenly had a change of heart.

“I thought to myself, ‘When I was 12 years old, I used to read Hawking’s books. I have a chance to spend some time with him now. Am I really too busy to spend time with Stephen Hawking?'” says Low.

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Later that day, Low and Hawking got to know each other while moving through a Monet exhibit, interrupted occasionally by kids asking to take a picture with the famous scientist. The next year, Low met Hawking in Arizona, where they had dinner at a Greek restaurant and caught a 3D showing of Warner Herzog’s Cave of Forgotten Dreams.

Then last June, in Hawking’s kitchen, Low pulled out a device and began recording signals from Hawking’s brain — the same brain responsible for discovering Hawking radiation and writing A Brief History of Time.

Hawking suffers from amyotrophic lateral sclerosis, or ALS, which doctors said would kill him a few years after he was diagnosed with the disease at the age of 21. This year he celebrated his 70th birthday.

The fear is that ALS will eventually stop him from being able to move his cheek muscle, which he uses to trigger an infrared sensor that selects words on a screen attached to his wheelchair. That would leave him trapped inside his own body, unable to communicate at all with the outside world.

That is why Hawking was so interested in Low’s invention, dubbed, perhaps a bit unimaginatively, the iBrain.

The fact that it measures the brain’s electrical activity is nothing new; researchers have been doing the same thing with electrodes for a long time now. The iBrain, however, is a lot more convenient.

It can be worn like a helmet, doesn’t require connecting cold electrodes to your scalp, and, as Low likes to say, “it weighs about the same as a pack of cigarettes, but is a lot better for you.” Not only is it more portable than the electrodes used by hospitals, but, according to Low, it also records at five times the frequency with far less noise. When paired with NeuroVigil’s algorithms, Low says that it’s been able to identify biological markers that had never been seen before.

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The idea with Hawking is to bypass his body and tap directly into his brain, letting him choose words on his screen at the same rate he did before (about one word per minute) without having to move a muscle. If they can differentiate between signals — say, the difference between thinking about moving your left foot versus your right hand — Hawking could gain even greater degrees of freedom and communicate more efficiently. After initial tests, Low says he’s been able to identify a signal that is “indicative of conscious intent.”

As miraculous as that sounds, the iBrain’s main function isn’t to help people with ALS connect with the outside world. It’s to detect diseases and monitor the effects of drugs on the brain. That makes it popular with the pharmaceutical companies, who can get input on new drugs during clinical trials.

It has also attracted the attention of the U.S. Military. Several months ago, the Navy sent Low and his team a soldier’s iBrain file without telling them if the subject was healthy or not.

“We said, ‘I certainly hope you don’t think this person is healthy, because through this one analysis we see patterns that are consistent with traumatic brain injury and post-traumatic stress disorder,'” says Low.

They also saw signs of an anti-depressant, which seemed strange because none of the markers for depression or schizophrenia were there. Turns out NeuroVigil was right about everything: the patient suffered from traumatic brain injury and PTSD and was taking antidepressants for anxiety.

“We felt pretty good about that test,” says Low. Carefully monitoring thousands of soldiers for signs of PTSD is both expensive and not always effective, which is a problem when you consider that 15% to 20% of deployed troops are estimated to be suffering from the disorder. A quick, easy test based on hard data could be invaluable.

Low says that NeuroVigil is currently 35% of the way done with the iBrain 2, which would also monitor a person’s heart rate. Even earlier in the planning stages is the iBrain 3, which Low envisions as the company’s first truly commercial device, a quarter-sized sensor that would link up with your iPhone or Android phone for around $100.

Low hopes to make checking your brain activity as easy as checking your blood pressure. Information would be sent to NeuroVigil, which would compile it into a database and notify people if they were showing signs of a neurological disorder or adverse reactions to a drug.

In 2009, when the company was just getting on its feet, Low says that venture capitalists tried to convince him to focus on a single disorder— apnea — which would make NeuroVigil an attractive target for potential buyers. Low refused and racked up debt on his credit card instead.

This Saturday, Low will appear at the University of Cambridge, where Hawking held the position of Lucasian Professor of Mathematics until 2009 — a chair once held by Sir Isaac Newton. The two will present the study’s latest results to the public, something that wouldn’t have been possible if Low had focused solely on apnea and sold the company. It’s a decision he doesn’t seem to regret.

“If you have a new kind of telescope, why would you want to point it at only one planet?” asks Low.

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