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Photograph by Dan Depew for Bloomberg Businessweek Photograph by Dan Depew for Bloomberg Businessweek

George Yu can take your temperature from two feet away, scan your house for leaky insulation, and determine the dampness of your basement with a gadget he invented called the Node, which works with an iPhone. The three-inch tube, which he describes as “a little Swiss Army knife of sensors,” records the world around it and beams the data to the phone via Bluetooth. The Node has so far caught the attention of hobbyists, who’ve bought 450 of them. Now, Yu is marketing the device to industries ranging from home improvement to health care through his Chattanooga-based startup, Variable Technologies.

The Node’s body consists of a tiny circuit board with three attached motion sensors inside a thumb-size plastic cylinder. Users can screw on other sensors that measure moisture, temperature, light, and color to either end. Yu’s innovation is combining the sensors in one flexible system and developing a compatible smartphone app that displays the environmental data the sensors pick up.

The 30-year-old engineer, whose family emigrated from China to Houston when he was 11, says he “took apart every toy my parents ever bought me.” Yu got his Ph.D. in electrical engineering from Georgia Tech in 2008. The next year he went to work on a Department of Homeland Security project at NASA’s Ames Research Center in Silicon Valley, designing an iPhone plug-in attachment to detect toxic gases. Though NASA killed that project, he thought phone-linked sensors could have broad applications.

In February, Yu built a prototype of Node and put the project on crowdfunding website Kickstarter, raising $76,000 in about a month. He raised an additional $300,000 from angel investors and started shipping Nodes in September. The basic motion-sensing device costs $150, with the screw-on sensors ranging from $25 to $75. One customer who raises parrots uses Node to measure temperature and humidity in his incubator. Marcus Ekeroos, who flies hot air balloons in Gothenburg, Sweden, measures his altitude and velocity with the device. He says he wants to use the Node’s readings to create “an advanced flight computer for [the] iPad made for hot air balloon pilots.”

Finding a mass market for the Node will be a challenge, says Jonathan Collins, a home automation analyst with tech industry researcher ABI Research. “When you’re looking at business and corporations and critical infrastructure, it’s not always their key focus to have something available for a cell phone,” he says.

Yu plans to build more sensor attachments (a gas sensor is in the works) and thinks Node’s flexibility will appeal to businesses. Behr, a paint company, is evaluating Node’s color sensor for a paint-matching app, and Yu says the thermal sensor can help building contractors find heat and moisture leaks. He has also made tools that allow developers to plug Node into their own apps. “We know we cannot build all the software,” he says. “There’s a lot of brilliant minds out there who have their own ideas.”