A marriage of electronics and textiles has led to a new system to monitor an athlete’s vital signs. Jon Excell reports

When he crossed the finishing line at last week’s New York Marathon Tim Borland could have been forgiven a slight feeling of superiority over his exhausted co-competitors. Because in a feat of physical endurance that would make the most dedicated joggers quake at the knees, the US athlete had just completed his 63rd marathon in as many days.

Borland’s almost superhuman feat — an awareness-raising initiative for research into rare childhood neurological disorder Ataxia-Telangiectasia (AT) — is testament to one person’s determination and the levels of fitness to which the human body can aspire.

But throughout his ordeal he was also helped by a clever piece of wearable technology that conveyed to his ever-present coach vital information relating to his ECG, heart rate, respiratory rate, skin temperature and movement.

By wirelessly transmitting feedback on his pace, food and fluids intake to his coach’s laptop, the system, known as the Bioharness, helped ensure that Borland was in optimum condition to complete his mammoth run.

Developed by New Zealand firm Zephyr Technology and launched at Hanover’s Cebit fair earlier this year, the Bioharness is one of the latest products to emerge from the field of smart textiles — where the marriage of fabric and electronics is paving the way for a range of smart wearable devices.

Chris Hardaker, product manager at Zephyr, told The Engineer that as well as measuring heart rate and rhythm, the system can also monitor the expansion and contraction of the chest. ‘From that, we can derive a breathing rate and data on chest cavity expansion,’ he said.

The system also contains a series of solid state sensors that can monitor posture, three accelerometers that measure acceleration in three dimensions, as well as a thermometer for measuring body temperature.

Hardaker claimed the system, which is made from a comfortable and flexible smart material, has distinct advantages over competing technologies which tend to use a hard plastic strap that is worn around the user’s chest. ‘We actually use a fabric, we use dry sensors so that there’s no skin irritation,’ said Hardaker.

As for the copious amounts of sweat produced by the average athlete, Hardaker said perspiration helps to boost and tidy the signal. The system is claimed to be so effective when wet that the company is testing it with a Canadian water skier and has begun to develop a version for swimmers.

Depending on the application, the data gathered by the Bioharness can either be logged on the device for later analysis or transmitted wirelessly to a laptop.

The current system transmits wireless data via an ISM link (industrial, scientific, and medical radio-frequency band). This, said Hardaker, has a range of about 100m that is ideal for gym and laboratory work and also has some trackside capability.

However, he revealed that later this month the company will launch a Bluetooth-enabled version of the system that can be used over GPRS networks and will have a far greater range.

The Bioharness costs just over £1,000. For this you get the strap, the software, and all the associated electronics. As it is possible to run several people against the same iteration of software, users can also buy additional straps for about £70.

Hardaker stressed that the device is a tool for specialists: ‘the level of knowledge of the human anatomy and physiology required to use it means that at this present time we are going for the elite sport and academics research market.’

However, Zephyr is keen to exploit the system’s undoubted potential in a consumer market, and Hardaker said that the firm is working on the processing system to turn the data into information that is far easier to interpret. ‘For the average Joe running down the street we need to say “you need to slow down” without giving him all this information,’ said Hardaker.

Customers include NASA (which is using the system to study sleep deprivation in preparation for future manned space missions), California’s Stanford University and Cranfield University in the UK. Zephyr is also working with a number of hospitals on using the device as an alternative to bedside monitoring units.

But the Bioharness is not its only product. The company recently launched a smart-fabric insole known as the shoepod.

Again aimed at athletes, this clever device measures the pressure applied to different parts of the foot in minute detail. ‘We do a statistical sample of the pressures of the foot over about eight locations on each foot and we do that very rapidly,’ said Hardaker.

Though the material is different to that used in the Bioharness, Zephyr’s skill in analysing physical data is again at the heart of the product.

‘The insole consists of small pressure sensors made from smart fabrics embedded in a specialised foam rubber with a well- known and understood compression rate,’ he said. ‘We’re measuring the compression of the foam and using an algorithm to analyse the forces applied. We’re doing it 800 times per second and we’re getting about 125 measurements across the average footfall.’

He added that the system was recently used on a marathon runner to analyse the impact of his fatigue levels on the mechanics of his feet and the way in which he was running.

‘You can see in the system points where the way he uses his feet changes enough that the efficiency starts to get degraded.’

He added that one New Zealand-based coach has been using the system to determine exercise regimes for athletes wishing to build up specific muscle sets. The company is also developing a special shoepod for diabetics.

For Hardaker, these products are just the beginning. He predicted that while most existing wearable monitoring systems have been designed to measure users’ heart rates, future systems will take into account an expanding range of physical factors. In the quest to build up an ever more accurate picture of what’s going in the human body, such systems could, he said, even take account of whether a user is tired or has a hangover.

Meanwhile, as he recovers from his epic run around the US, Tim Borland is modest about his achievement, pointing on his blog to a 20-year-old Canadian cancer sufferer with a prosthetic leg who, back in 1980, ran a marathon a day for 146 days.