Add footwear to smartphones, smartglasses and smartwatches.

We've got smartphones, smartglasses and smartwatches - but how about smart slippers?

Such is the intriguing potential of Kiwi-designed technology that opens the door to a new generation of "wear-and-forget" clothing which gleans electricity from energy created by our own bodies.

The scientist behind the newly unveiled technology, Dr Ben O'Brien, said that while smart slippers were a quirky idea he was just toying with at this stage, it was possible to create footwear for elderly patients monitored by carers or medical staff.

As they walked, the slippers could generate enough energy to power a sensor potentially sending movement or location data.


"They might be letting doctors or nurses know if there's anything wrong - but as far as the wearer has to know, it's just a pair of slippers."

Dr O'Brien and his colleagues secretly developed the so-called "energy scavenging" system at Auckland University, where he is an honorary academic. His spin-out company, StretchSense, has now signed a licence deal with the university's commercial arm to eventually market the product, expected to be within two years.

So how exactly does it work?

It builds on a StretchSense-developed sensor for the sports and fitness market, which comprises a low-energy Bluetooth circuit made of fabric so it can easily be sewn into sports garments.

As an athlete moves, the sensor stretches, providing real-time accurate information about his or her movements. "But it turns out you can do another thing with this technology," Dr O'Brien said.

"When it is stretched and deformed, you can actually harvest that mechanical energy and convert it into electrical energy.

"From a technological point of view, this has been possible for maybe two decades now - but what has really changed is that it's matured and got to the point where we can start to make products with it."

Completely oblivious to the wearer, the technology could be permanently integrated into clothing, shoes or sports equipment. "Maybe it's a breathing strap and when you go for a run, it automatically comes alive and your shirt starts telemonitoring your heart or breathing rate, or potentially location information."

His team were starting with wireless sensors, considered an ideal application because they required little power. "The sensors that we sell presently only require 50 microjoules, which is a very, very small amount of energy to send data back."

Charging your smartphone while on the move, however, was probably a step too far. "You would need to capture a thousand times as much energy - and the problem isn't so much the generation, but how much energy you can take from a person before you start annoying them."

He expected the first products using the technology to hit the market within two years.

How StretchSense's new energy-harvesting tech works:

• When we move our bodies, we create what's called mechanical energy, which is the sum of potential and kinetic energy.

• When StretchSense's technology, consisting of a low-energy Bluetooth circuit made of fabric, is built into clothing which stretches along with the body, it can "scavenge" this energy and convert it into a small amount of electricity.
• That electricity can then be used to power a small sensor which could relay information about the wearer's heart or breathing rate, or location, creating self-powering, or what's called "wear-and-forget" wearable technology.

• This could be in the form of anything from a skin-tight training shirt to "smart slippers".