There are thousands of iPhone accessories, but a Minnesota company has invented one so different that experts say it could change the way smartphones are used.

At the annual Consumer Electronics Show in Las Vegas this week, Canopy Co. of Minneapolis will introduce its Sensus touch-sensitive iPhone case. The case, which contains its own touch sensors on the back and one side, plugs into the electrical connector on the bottom of the iPhone and becomes an extension of the phone's touch-sensitive screen. As a result, what was a smartphone with one touch-sensitive surface becomes a gadget with three touch-sensitive surfaces -- something new under the sun.

Canopy officials and iPhone experts said that an iPhone with three separate touch-sensitive surfaces opens up new possibilities for games and other software that are designed specifically for the Sensus.

"Having a case that is a touch screen is definitely new," said Michael Morgan, an analyst for mobile devices at ABI Research in New York.

Gene Munster, a Piper Jaffray analyst who is widely quoted on Apple's products and strategies, agrees.

"I've not seen anything like Sensus, and I'm surprised to see it here in Minneapolis," which is not known as a hotbed of smartphone industry development, he said. "What Canopy is doing fundamentally changes the iPhone into a much more comprehensive gaming device, and that's logically the first market they'll go after."

Canopy CEO Andrew Kamin-Lyndgaard, a self-described obsessive idea guy whose background is in advertising, agrees that games are his biggest potential market. "We're following the money," he said. "And the gaming market for iPhones is where 80 percent of the money on apps is made."

But non-gaming apps also could be big. "The killer part of this product is accessibility," said Matt Pacyga, Canopy's chief strategy officer. "We're opening up smartphones to the blind."

Canopy plans this year to offer software that will make sensors on the back of the case correspond to the Braille symbols used by the seeing-impaired. That would allow seeing-impaired iPhone users to type text messages on the back of the case, which has raised plastic surfaces that enable someone to touch the correct area, he said.

The iPhone would automatically convert the Braille symbols into the conventional alphabet, and read each letter aloud so the user could correct any typing errors. Such an arrangement could be more effective than the voice-recognition software seeing-impaired users must rely on today.

"Voice recognition software for smartphones is not very accurate, and it has limited functionality," said ABI's Morgan.

Other potential uses of the Sensus case are related to its ability to be activated by the apps that use it. When those apps aren't in use, or when a phone call is being made, the case's electrical properties are turned off, Kamin-Lyndgaard said.

"For instance, I could set the phone so that browsing a website such as the Star Tribune's would activate just the sensors on the side of the case, so that I could use my thumb to scroll through an article," Kamin-Lyndgaard said.

The Sensus case draws its power from the iPhone, but it uses less of the phone's battery power than the phone's Bluetooth wireless connection to a phone earpiece, Pacyga said.

In any case, Canopy will be competing in a huge worldwide market for smartphone cases that totaled $6.7 billion in 2012 and is projected to be $8.2 billion this year, ABI's Morgan said. About 75 percent of iPhone users buy a protective case, he said.

When available at midyear, Sensus cases for the iPhone 4, 4S and 5 are expected to sell through retail stores for $59 to $99, Kamin-Lyndgaard said. He also hopes to make other touch-sensitive cases for either the iPad Mini or the iPod Touch.

Sensus is the brainchild of Kamin-Lyndgaard, who designed it nearly a year and a half ago, then had it built to his specifications by mostly Twin Cities software firms and a third-party manufacturer in China. His game plan is to internally develop some apps for a Sensus-equipped iPhone, while encouraging other firms with well-known iPhone game titles to develop special versions for the Sensus.

Since starting in early 2010, Canopy has grown to 10 people and has raised about $3.8 million from Twin Cities angel investors, Kamin-Lyndgaard said. A patent application for the Sensus case is pending; Canopy's patent attorney, Steven Lundberg, declined to be quoted for this article.

"All indicators are that we have a commanding lead in this market," Kamin-Lyndgaard said. "That's based on our conversations with independent software developers, a patent search and what we've heard from technology companies."

Steve Alexander • 612-673-4553