Smart Clothes: Textiles That Track Your Health

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Smart Clothes: Textiles That Track Your Health

http://www.sciencedaily.com/releases/2008/03/080329121141.htm

Garments that can measure a wearer's body temperature or trace their

heart activity are just entering the market, but the European project

BIOTEX weaves new functions into smart textiles. Miniaturised

biosensors in a textile patch can now analyse body fluids, even a

tiny drop of sweat, and provide a much better assessment of someone's

health.

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See also:

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Fitness

Today's Healthcare

Matter & Energy

Detectors

Nature of Water

Materials Science

Reference

Biosensor

Sweating

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Hyperthermia

It is 7 o'clock in the morning. You check yourself in the mirror,

adjust your collar, and consider the hectic day ahead. But at least

you know that the stress won't damage your health, for this is no

ordinary set of clothes you are wearing. Embedded within the fabric

are numerous sensors, constantly monitoring your vital signs. If

danger signs are detected, the garment is programmed to contact your

doctor – and send a text message telling you to take it easy.

A cluster of EU research projects (SFIT Group) is supporting this

burgeoning field of smart fabrics, interactive textiles and flexible

wearable systems. Luprano, a researcher at the Swiss Centre for

Electronics and Microtechnology (CSEM), coordinates the BIOTEX

project.

" One of the most obvious applications for smart fabrics is in the

medical field, " he says. " There has been a good deal of progress with

physiological measurements, body temperature or electro-cardiograms.

But no-one has yet developed biochemical sensing techniques that can

take measurements from fluids like sweat and blood. We are developing

a suite of sensors that can be integrated into a textile patch. The

patch is a sensing and processing unit, adaptable to target different

body fluids and biochemical species. At the very least, some basic

biochemical analyses could complement the physiological measurements

that can already be monitored. In some circumstances, fluidic

analysis may be the only way to get information on a patient's health

status. "

Sensing success

But there is a simple reason why researchers have shied away from

developing smart textiles for fluid monitoring: it is extremely

tricky. How do you collect a fluid and transport it to a biosensing

unit? Can you perform non-invasive blood tests? Can measurements be

reliable and accurate with tiny volumes of liquid?

The BIOTEX partners – universities and small enterprises from Italy,

France and Ireland – have collaborated with CSEM to overcome some of

the technical barriers to biosensing textiles.

One of the main achievements of the project has been the development

of a suite of prototype ionic biosensors, capable of measuring

sodium, potassium and chloride in sweat samples. Another probe

measures the conductivity of sweat and a miniaturised pH sensor uses

colour changes to indicate the pH of sweat. An immunosensor, which

could be integrated into wound dressings or bandages, can detect the

presence of specific proteins in fluid samples.

These biosensors are not just scaled-down versions of existing

technology, Luprano is keen to point out. " Many of the chemical or

biochemical reactions used in sample assays are non-reversible and

some part of the biosensor has to be replaced. When you monitor

continuously you can't do that – you need a sensor that binds your

substrate reversibly. Also, the BIOTEX sensors work on tiny volumes

of liquid, so we had to come up with innovative designs and materials

that would make it possible to miniaturise the sensors and make them

compatible with fabrics. "

Several of the BIOTEX probes, including the pH sensor, use colour

changes or other optical measurements. For example, as sweat passes

through the pH sensor it causes an indicator to change colour which

is detected by a portable spectrometer device. The immunosensor

technology works in a similar fashion. Plastic optical fibres (POFs)

are woven into the fabric so that light can be supplied to the

optical sensors and the reflected light directed to the spectrometer.

Small and smart

The BIOTEX oxygen probe measures levels of oxygen saturation in the

blood around the thorax using a technique called reflective oximetry.

A cluster of POFs allows a large surface of the thorax to be

illuminated and improves the collection of the reflected red and

infrared light used for the oximeter sensor. Signal processing also

improves the sensitivity of this method.

Having an array of biosensors in a textile patch is one thing, but

how do you get fluids to them in the first place?

" The volume of fluid secreted from sweat glands is just a few

millilitres over a small surface, " says Luprano, " and the body's heat

means this is rapidly vaporised. We needed some kind of pump that

could collect sweat in one area and bring it to the sensor array,

where it could be channelled through each sensor. "

The solution uses a combination of hydrophilic (water-loving) and

hydrophobic (water-repellent) yarns. It is possible to weave these

two threads to direct the sweat through fabric channels to the sensor

array. It is a passive system using no power, thereby reducing the

power demands of the BIOTEX system (and the weight of a battery pack

that the wearer would have to carry).

In the first BIOTEX trials, the smart patches will be worn in clothes

by people with obesity and diabetes, as well as athletes. Once the

technology has been validated, the plan is to take on industrial

backers to commercialise it. Meanwhile, a large EU-funded project

within the same SFIT group, called PROETEX, is integrating the

technology with other micro- and nanosystems for specific

applications (fire fighting and rescue teams).

However, whilst BIOTEX has solved several of the technical aspects of

continuous biochemical monitoring, Luprano calls for more research

into the application of this technology.

" It's new and healthcare providers are not used to it. We are not

used to the information that continuous, remote monitoring can

provide – so different to the one-off laboratory tests that are

usually taken. BIOTEX makes this remote monitoring possible, but more

research into the links between these indicators and disease

conditions and states will make it realistic. Nevertheless, in the

long-term we expect continuous monitoring, made possible with smart

textiles, to make a major improvement to the way we approach the

treatment of metabolic disorders and leisure. "