Look Ma, No Batteries

A UVA professor and his team of students are powering the Internet of Things

By Robert Viccellio

Left to Right: Ben Calhoun, PsiKick cofounder and CEO Brendan Richardson, and senior design engineer Yousef Shakhsheer with their ultra-low-power wireless, batteryless computer chip. Dan Addison

The Internet of Things is regarded by many as the next big technological revolution. How big? According to Cisco Systems, the number of things connected to the Internet exceeded the number of people in the world back in 2008.

But the Internet of Things is only just getting started. By bringing together the capabilities of the Internet, an expanding wireless network and ever-shrinking electronic devices, the Internet of Things, or IoT, is connecting devices and people in ways that have the potential to change how people will go about many of life’s basic functions, from monitoring our health with wearable sensors to smart cities that constantly respond to data transmitted from things like traffic lights, parking meters and subway trains.

This graphic—created by Libelium, a company that builds open source sensor platforms for the Internet of Things—shows an example of what a “smart city" might look like.

*Click to enlarge »*

The IoT already includes functions as simple as connecting appliances to smart phones (one example at UVA—washers and dryers in dorms are texting students when their clothes are ready) and as complex as collecting global climate data with billions of sensors placed around the world.

The latest Internet protocol system, IPv6, expands the number of possible IP addresses that locate and identify computers or entities on networks to a number so large that every atom on the face of the earth could have 100 million IP addresses. Clearly, assigning unique addresses to things on a connected network is not an issue. However, there are barriers to a useful and beneficial IoT, including thorny questions related to privacy and security that are ongoing topics of debate.

Everything You Ever Wanted to Know About Computer Chips, But Were Afraid to Ask

Almost everyone has heard of computer chips, but not nearly as many can explain what they actually do. Professor Calhoun explains:

A computer chip is another name for an integrated circuit—basically a whole bunch of transistors and resistors and other electrical components integrated onto one piece of silicon that can be really tiny. The processor in your laptop is an integrated circuit. The radio in your cell phone is on a chip and is also an integrated circuit. Conventionally, people think of computer chips as processors, but an integrated circuit is much more than just a processor. Modern cars have 40 or 50 integrated circuits. Some of them are little computers than control the car’s anti-skid function and others are integrated circuits on the stem of every tire that monitor tire pressure.

What we’re building is a fairly complicated chip that has a complete wireless sensor system on it. It can sense information through various kinds of sensors. It can do computation to extract information from the raw data and it has integrated radios that allow it to communicate. Think of it as a very simple smart phone, all on one computer chip. It’s very simple—it doesn’t have a touchscreen or microphones—but it does a lot of the same things. It can take data in from sensors, it can process that data and wirelessly communicate that data.

Another obstacle is powering this massive network of interconnected sensors and devices. “It’s going to happen in some form or another and one of the big technical challenges for the Internet of Things is power consumption,” says UVA engineering professor Benton Calhoun (Engr ’00). “If you want to have sensors embedded in tables and walls and coffee cups and parking spaces, you can’t go around changing the batteries. People are predicting a one-trillion-node Internet of Things. Even if every single battery lasted 10 years, for a trillion sensors you’d still have to change 275 million batteries a day.”

That’s a problem that Calhoun and his team of about 15 Ph.D. students and half a dozen undergraduates are solving. In his research lab in Rice Hall, they are creating computer chips that have the potential to become a foundational platform for the Internet of Things.

“The main difference in our technology relative to others peoples’ technology is that we can provide all those necessary functions—sensing, computation and communication—at much lower power levels than other people have been able to do. Like 100 times lower. Or 1,000 times lower,” Calhoun says. “That allows us to contemplate running those functions in a system that doesn’t need a battery, that harvests its energy from its own environment.”

Calhoun, who earned his Ph.D. at MIT and is one of the world’s leading experts in ultra-low-power circuit design, has built a prototype of a wearable chip that harvests energy created by body heat to monitor and transmit data about heartbeart, brainwaves and major muscle activity—all without ever needing a battery.

A prototype of a wearable health monitor developed by Calhoun and his team. Dan Addison

These ultra-low power, batteryless chips are the product of a collaborative effort between UVA, the University of Michigan and the University of Washington, and are being developed for broad application and mass production by a Charlottesville-based spinoff company called PsiKick. The universities hold the patents on the technology and license the inventions to the company.

“UVA has enabled all this to happen,” says Calhoun. “I have amazing students and there’s no way we could have done this without the students. They are the underlying engine that makes all of this possible. And UVA builds in the capability for professors like me to continue to run my research group and develop new technology, but also have the ability to get a company going.”