Inventor Dean Kamen holds more than 440 patents, many for medical devices that have improved the lives of thousands, including his wearable insulin pump, iBot wheelchair and portable dialysis machine. His Segway Human Transporter, while ultimately more of a curiosity than a financial success, did make him famous. But the invention with potentially the greatest impact is the SlingShot, a vapor compression distiller that can make even the most polluted water potable. Considering that 50 percent of all disease is caused by water-borne pathogens, the plug-in device, which is compact and needs no filters, charcoal or more energy than a hair dryer to operate, may be Kamen's most significant invention yet.

Director/producer Paul Lazarus believes it is. Lazarus previously collaborated with Kamen on films about the Segway and his FIRST robotics competition for young science students, and made the SlingShot the focal point of his new, very personal documentary about Kamen. Aptly titled "SlingShot," it chronicles the 15 years Kamen has devoted to developing the device, and reflects both the David vs. Goliath aspect of tackling a huge problem like the water crisis and an incident from Kamen's youth. Pushed off his bicycle by a neighborhood bully, Kamen stood up to his tormentor and was never bothered again.

Interviews with Kamen and his parents provide more telling details. The undersized, dyslexic boy who questioned everything and was obsessed with machines grew up to own a mansion with secret passageways and a helicopter in his garage, but remains unmarried and childless in order to focus on his work. Since the death of his brother Bart from cancer in 2012, he's more aware than ever of life's ticking clock. "I want to work on really big problems and solve them — or at least try," he tells the camera.

While Kamen is shy and reluctant to discuss his personal life, believing that his work is far more important, Kamen gave Lazarus no preconditions; only inventions that were in early stages were kept off-camera. "The fact that we had worked together on numerous projects before the movie created a trust between us and an openness," the director says, although "getting time with this very busy man was always a challenge."

Lazarus wanted to convey the many facets of this modern genius, including "his indefatigability — he never stops trying to fix things about the world — particularly with regards to health — his humor and wit, the fact that he retains his childlike wonder about the world, and his uncanny ability to look at a problem and see it differently than everyone else."

When Kamen told him about the SlingShot, "I had an instinct that this was going to be his most important innovation ever," Lazarus says. "I wanted to see if I could capture an idea in Dean Kamen's head being turned into a reality."

Dean Kamen on a SegwayInventor Dean Kamen, inventor of the Segway, has worked on a low-cost, low-energy water filter for a number of years. (Photo: SlingShot Movie)

His goals approaching the film were threefold: "help spread the use of this life-saving technology, inspire everyone — particularly young people — to pursue careers in science and technology and help alter attitudes about water in general." As Kamen points out in "SlingShot," the Western world doesn't recognize the urgency of the global water problem, or the fact that drugs and hormones are contaminating the U.S. water supply.

The film follows the SlingShot's development through various testing and real world trials, from its first trial in Honduras in 2006 to Ghana in 2011, but it is still being modified and improved. Kamen and his team at DEKA "are hard at work on getting the cost curve significantly down. The price is a moving target as the cost is very much affected by how many are being made," Lazarus says. "Models in Honduras and Ghana were prototypes and for testing purposes only. It will take tens of thousands to have major impact on the world."

That obstacle doesn't deter Kamen, who announces, "I want to get clean water to everyone on the planet." Lazarus believes the SlingShot "might turn out to be his most impactful invention," but thinks Kamen would reserve that distinction. "He would say, 'It hasn’t happened yet.'"

Lazarus, who is now working on a feature documentary about the arts in America called "Think Big," is gratified that Kamen has seen various versions of "SlingShot" and "liked it very much." He hopes audiences will feel the same when the film opens in New York on July 10, Los Angeles on July 17, July 26 in Philadelphia, and other cities to follow. In addition to "more knowledge about the world’s water challenges," Lazarus hopes viewers will come away with "hope, inspiration, the desire to help make change."

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