Microchip Technology has launched a toolkit that lets customers build sensor networks that use the human body instead of wires to communicate.
Launched at Embedded World, Nuremberg, this week, the BodyCom network uses capacitive coupling to let wearable sensors pass data to other systems as soon as the person touches a place on the receiver.
We wanted to make it really low cost, using the lowest-cost 8-bit microcontrollers that we have,” says Microchip Technology business development manager Lucio Di Jasio. “Door entry was the first implementation. A user carrying a BodyCon keyfob can unlock a door simply by touching a receiver mounted on it. If you visit our Milan office you have to use one of these.”
But customers have already begun to develop less-obvious applications, Di Jasio explains: “One customer has a bike helmet – the bike won’t start if you’re not wearing the helmet".
One advantage of using capacitive coupling through the body, Di Jasio claimed, is that it does not need the approvals of competing wireless technologies that use the RF (radio frequency) spectrum: “The amount of radiated energy is below the minimum set by the Federal Communications Commission,” he says.
The technology was derived by one of Microchip Technology’s customers. The chipmaker has taken it further, and patented the implementation. “We are not going to ask for royalties,” Di Jasio says. “We give away the source code. There is just a click-through licence on the website: we just ask that you use a PIC [peripheral interface controller] microcontroller to implement it.”
To minimise the cost of implementation in the wearable nodes, most of the processing is performed in the fixed unit or ‘basestation’. “The system is asymmetric,” says Di Jasio, adding that along with a microcontroller only one other analogue front-end component, originally developed by the company for the remote keyless entry systems used in cars, is needed in the wearable tag or fob.