The Internet of Things is nothing without batteries and plugs. But it's possible to build a sensor network that uses harvested energy that comes from changes in temperature, vibrations, wind and light, as Texas Instruments (TI) will demonstrate at the Consumer Electronics Show in January.
The idea of harvesting power has a long history and there are many applications of it today. However, big solar panels or large sensors that can capture energy from vibrations, heat and light are impractical in many Internet of Things sensor applications, which are tiny in size.
TI said it has developed electronics capable of taking small amounts of power generated by harvested sources and turning them into a useful power source. This means that the sensors used to collect the energy can be small as well.
All these ambient energy sources, such as the difference in temperature in a pipe carrying hot water and the outside air, can generate 300 to 400 millivolts, which isn't enough to power anything. TI has built an "ultra-low powered" DC-to-DC switching converter that can boost this power to 3 to 5 volts, which is sufficient to charge a battery, according to Niranjan Pathare, senior marketing development manager at TI.
To power wearables, the company has demonstrated drawing energy from the human body by using harvesters the size of wristwatch straps, Pathare said. It has worked with vibration collectors, for instance, about the same size as a key.
It's possible that a smartwatch could use two harvested power sources, light and heat, from the body. These sources may not gather enough power to keep a smartwatch continuously operating without action by the user to charge it, but it may give the user's device a lot more battery life.
"Obviously, the longer you can make that [battery] last the happier the consumer is going to be with its performance," said William Cooper, a TI product marketing engineer.
The technology has many applications in industrial and home environments. If a device or sensor isn't connected to a power network, it will need a battery. Vendors will say that these batteries have the potential of lasting for years since they are only transmitting small amounts of data. But, still, who wants to worry about a battery?
Of the work done by Texas Instruments, Steve Ohr, an analyst at Gartner, said, "they have the parts that will take this micro-power input and actually make some useful voltage and current that could power something."
Ohr said there's a lot of work that needs to be done before this technology finds its way to the market in uses such as powering a smartwatch, specifically in improving the sensors that collect energy.
"You really need a big surface area to generate a very small amount of electricity," Ohr said, and it will take more work on the materials used to make the sensors before they are ready for the wearable market, in particular.