Self-charging smartwatches and health trackers could be a step closer after British engineers develop tiny mechanical devices powered by MOVEMENT
- Biggest drawback of smartwatches is the requirement to charge them nightly
- University of Edinburgh engineers have developed tiny motion-powered devices
- These are twice as powerful as similar existing devices, researchers claim
- They could offer an energy-efficient and sustainable alternative to batteries
Self-winding watches that are powered by the motion of the wearer have been around since the late 18th Century but, until now, no one has managed to create a similar technology for power-hungry smartwatches and health trackers.
Now engineers from the University of Edinburgh have developed tiny mechanical devices powered by movement, which they claim could offer an energy-efficient and sustainable alternative to batteries used in wearable technologies.
Smartwatches are one of the most popular wearable devices globally, and are expected to reach shipments of more than a quarter of a billion units by 2025.
But one of their biggest drawbacks is the requirement to charge them up nightly, making it difficult for wearers to take advantage of features such as sleep tracking.
The new method – devised by a team of three PhD students – creates so-called ‘piezoelectric’ materials more quickly and efficiently than previous techniques.
The researchers claim the new mechanisms are twice as powerful as similar existing devices, bringing self-charging smartwatches and health trackers a step closer.
Smartwatches are one of the most popular wearable devices globally, and are expected to reach shipments of more than a quarter of a billion units by 2025
Using a high-voltage power supply, the researchers were able to make 3D sponge-like materials from the fibres, which were then cut into 1cm-squared pieces, fitted with electrodes and wires, and encased in silicon.
HOW DO FITNESS TRACKERS WORK?
Fitness trackers such as Fitbits or smart watches monitor heart rate using a technique called photoplethysmography.
The tracker sends green light through the skin which is partially absorbed by arteries.
As you exercise, these arteries expand as blood flow increases – meaning more green light is absorbed rather than reflected back to the tracker.
The tracker estimates your heart rate by seeing how much light is reflected back.
The amount of light that passes back through the skin to the tracker can be affected by the amount of melanin in the skin, and any tattoos.
‘With ever-growing interest in the development of electronic wearable devices and implants, the generation of electronic waste and the limitations associated with battery capacity remain some of the key challenges to overcome,’ said PhD student Francisco Diaz Sanchez, of the University of Edinburgh’s School of Engineering, who led the research.
‘The materials we have developed bring us one step closer to the sustainable development of wearable electronics.’
The team devised the new approach by tweaking the chemistry used in the production of ultrafine fibres of a material called PVDF – a versatile substance that generates electricity when pressure is applied to it.
Using a high-voltage power supply, the researchers were able to make 3D sponge-like materials from the fibres, which were then cut into square centimetre pieces, fitted with electrodes and wires, and encased in silicon.
Tests of the devices’ power output show they can produce 40 microwatts of electricity per square centimetre – twice as much as the most powerful type of existing piezoelectric generator.
Further development of the structures could extend the life of – or even replace – conventional batteries in wearable technologies, helping to reduce electronic waste and energy consumption, researchers say.
The devices could be woven into products such as motion-sensing clothes and t-shirts that monitor breathing and heart rate. Pictured: multiple devices connected to form a more complex and powerful generator
The motion devices could offer an energy-efficient and sustainable alternative to batteries used in wearable technologies
The materials could also have applications in the next generation of smart textiles and be woven into products such as motion-sensing clothes and t-shirts that monitor breathing and heart rate.
The new study, published in the journal Nano Energy, was supported by Mexico’s National Council of Science and Technology.
Earlier this year, engineers at MIT and the Rhode Island School of Design unveiled a t-shirt that can ‘hear’ your heartbeat and monitor your cardiac rhythm in real time.
It was created using an ‘acoustic fabric’ that works like a microphone, first converting sound into mechanical vibrations and then into electrical signals, in a way that is similar to how our ears hear.
When woven into a shirt’s lining, the fabric can detect a wearer’s subtle heartbeat features.
Smartwatches are less effective at tracking the health of people with dark skin, study finds
Joggers and other fitness fans are increasingly turning to smartwatches to measure their heart rate during exercise and for overall health monitoring.
But a new study by the University of Alberta in Canada has found that the trendy gadgets are less effective at tracking the health of people with darker skin tones.
The study suggests this may be because the signalling process, which uses beams of light to detect heart rate and rhythm, might not work as well on darker skin that contains more melanin, as it absorbs more light.
However, the algorithms that power these devices are often developed by and tested on homogeneous white populations, which may mean the problems are not being identified prior to launch.