In public Behar speaks softly, and his sentences bear the occasional hesitation of someone for whom English is a second language. (His first is French, and he is also fluent in Italian and German.) In English, Behar will sometimes cut off a sentence halfway through and begin again, or give up after conveying the general idea. Onstage and in interviews, Behar's attitude is one of polite forbearance — the child made to sit still for a portrait. When he listens, he sometimes removes his Up band and turns it over in his hands. If a question particularly interests him, he grows more animated, illustrating his thoughts with gestures. His hands roll forward like waves, one thought proceeding neatly to the next, a tide of answers coming in to shore.

He grows most animated when discussing the Up, which was among the first fitness trackers of its kind. Most products created by designers are used relatively infrequently by their owners — the lemon zester you buy and then pull out twice a year. But devices tied to smartphones are different. People who wear the Up open its companion app an average of 20 times a week. "Frequency of use is off the charts," Behar says. "It becomes an incredible way for us designers to connect." The technology still feels primitive — the Up tallies things like steps taken or hours slept, and then shows them on a screen. But its wavelike texture and bold colors convey motion in a way that turns the device into a statement. It says: I take care of myself.

Behar believes the future belongs to objects like Up, which give people more control over their lives through sophisticated but subtle applications of technology. He's broadly interested in "moving design closer to the body," through objects that adapt to you over time. "Our principal role as designers is to accelerate new ideas, and the adoption of new ideas," he says to the audience at Basel. "This is a way to do that."

Behar's trip to Switzerland is a homecoming; he grew up 120 miles away in Lausanne. Among the attendees of his panel are his parents, Henry and Christine, and an aunt who is visiting from Turkey. Behar's aesthetic mission has extended even to his parents' home in Lausanne, where he disliked the chairs so much that he recently told his mother to get rid of them on the promise he would replace them. She complied with this request, but he has yet to replace any of the chairs months later, and if you find yourself introduced to Christine Behar she may relay this information to you within the first few minutes of your conversation. (He has since designed some chairs for her.)

"I never felt truly at home in Switzerland."

Behar's longtime girlfriend, art advisor Sabrina Buell, is here in Switzerland as well. She's traveled to Europe with Behar and their daughters, three-year-old Sylver and six-week-old Soleyl. Behar also has a seven-year-old son, Sky, from a previous relationship. (His parents chose a "Y" name for Yves in honor of Henry, and he has continued the tradition with his own children.) Though Behar retains his Swiss citizenship, in most ways he is a fully assimilated Californian: the surfing, the yoga, the utopian embrace of technology. Even his own countrymen can seem wary of him — when Behar checks into his hotel room, which Buell has reserved under her name, the front desk refuses him, thinking him a potential imposter. "The Swiss," Behar says, "can be very difficult."

After the panel, Behar shakes hands with design students from the audience, takes their business cards and autographs a festival program. I had traveled to Europe to see Behar at work, and when he spots me after his talk, he invites me to join as he and his family browse the art collection across Art Basel's courtyard.

Inside the gallery, a wire sculpture catches Behar's eye. The untitled work, by the artist Fred Sandback, consists of a piece of elastic cord and steel snaking out of a wall to form a three-dimensional rectangle, 102 inches long, hovering in space. The sculpture, which Sandback completed in 1968, represents the kind of minimalism that is easily dismissed. You could have made that, Behar's mother says to his father in French. But to Behar, the wire resonates because of its radical simplicity. It is, he says, something to aspire to. "It's about creating a maximum effect with the lowest means," he says. The work reminds him of his earliest days as a designer, when he couldn't always afford the materials he wanted, forcing him to improvise.

The wire sculpture's price tag is $450,000. Behar's father, who is 75, makes a face and sighs. "I must be getting very old," he says.

Henry Behar comes from a family of Sephardic Jews who were forced out of the Jewish ghetto in Vienna in the 1800s and settled in Turkey. Christine Behar grew up in East Germany, and at the age of 17 escaped into West Berlin via an underground tunnel. They met at a nightclub in London, and married in 1966. Yves was born a year later. As a child, he often played with a hand-me-down Lego set given to him by a cousin. He built houses from the plastic bricks, growing frustrated whenever his creations failed to achieve a perfect symmetry. Behar says he wanted them to look "resolved." That play evolved into frequent teenage tinkering in his parents' garage, and at 16 he decided to pursue design. Three years later he enrolled at the Swiss branch of the Art Center College of Design. By then, he was chafing against his Swiss surroundings: the country seemed increasingly small and closed-minded to him. "I never felt truly at home in Switzerland," he says. He transferred to the main branch of the Art Center in Pasadena, California in 1990.

At the time, Behar saw California as little more than a way of escaping Switzerland. But his timing was impeccable. He arrived just as desktop computers were coming to the fore, and Silicon Valley manufacturers were looking to industrial designers to differentiate their anonymous beige PC towers. Upon graduation, Behar moved to San Francisco, where he worked as a junior designer at big firms Lunar Design and Frog. (Among other desktop designs, he worked on the award-winning Pavilion from Hewlett-Packard.) Along the way, Behar absorbed Silicon Valley's genetic optimism about the social impact of technology. It has since become a hallmark of his work. "Hollywood tends to have a dystopian view of technology — I think it sells more movies," Behar says. "But I can't escape the environment I'm in, which is San Francisco, which tends to think in a utopian way about technology. It certainly makes mistakes, but I tend to have a positive view of it."

Behar founded Fuseproject in 1999, with the aim of serving clients who understand what good industrial design can do. The firm's early work included a perfume bottle, a shampoo bottle that he designed for his hairstylist, and a recycleable shoe with an intuitive microchip designed for an exhibition at the San Francisco Museum of Modern Art. The shampoo bottle won a design award, and the shoe brought Behar wide attention. His roster of clients multiplied, and in 2004, just five years after starting his own firm, he had solo shows at SF MOMA and in Lausanne.

As the demand for Behar has grown, Fuseproject has swelled to more than 70 employees. If you value thoughtfully designed tools and have some disposable income, there's a decent chance that something from Yves Behar's imagination is in your house, in your office, or on your wrist. Along the way Behar has become a wealthy man, although it's hard to say exactly how wealthy: the startups he has worked with most closely have yet to go public. He stands to make millions from the partial sale of Fuseproject, and will remain CEO, promising that very little will change in the day-to-day running of the company. "Overall," he says, "it's an ambition to make design central to more businesses. And it's a recognition that there's much more work to do in that sense, internationally."