Now a professor at Linkoping University in Sweden running a department dedicated to bioelectronics, Turner says a study he led at Cranfield University in Britain found the devices now generate annual sales of $13 billion and spawned 6,000 research papers last year.

Biosensors use biological material combined with an often portable detector to diagnose disease or pick up pollutants in the environment.

Companies have been quick to exploit the potential of a technology that can detect and track diseases from diabetes to cancer, but demographic changes and economics suggest this market could balloon in years to come.

As governments around the world struggle with healthcare costs and ageing populations, the benefits of technology that can keep patients out of expensive hospital beds and off costly drugs are a big attraction.

Healthcare agencies are increasingly decentralizing complex diagnosis and treatment, to local doctors' offices and even into the home, which helps contain the institutional costs of big centers like hospitals.

And capitalism's tendency to push towards the consumer is encouraging more people to buy health monitoring equipment directly. Only a decade ago, the average consumer would not have had such easy access to a cheap home blood pressure monitor or an electronic in-ear thermometer, for instance.

As medicine becomes personalized, tailored much more to an individual's lifestyle, genetics and responsiveness to treatment, improved monitoring and detection will be key.

"So far we have had a 'one-size-fits-all' approach to medicine," Turner told Reuters. "We have treated rather than kept well."

He is working on sensors that could improve care for the elderly by being woven into clothes or implanted in the body, able to beam data to a remote recorder to pick up any biological changes that need medical attention.

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About 85 percent of the biosensor market is dominated by monitors for diabetics to self-check their blood-sugar levels - a lucrative market as diabetes is the fastest growing chronic disease in the world. But scientists are expanding their use into other illnesses, as well as general health and environmental monitoring.

The potential has fuelled an intensified research effort and the commercial interest was given a populist kick earlier this year by a new $10 million prize from the U.S.-based X Prize Foundation for whoever can create a Star Trek-style medical 'Tricorder'.

On the television show, that device allowed the fictional USS Enterprise medical officer Dr McCoy to diagnose illness simply by scanning the patient.

Biosensors rely on the ability of biological molecules to recognize disease targets, either by binding to them and giving the detector something it can see, or by provoking a chemical reaction that gives off a by-product that can be detected.

The X Prize points to one of the biggest hurdles - a sensor that does not need a blood or tissue sample to work.

"The challenge is definitely to work on non-invasive technologies," said Maximilian Fleischer, head of chemical and biosensors at Siemens Corporate Technology.

"We are anticipating that the application of biosensors in point-of-care diagnosis will be a large upcoming market."

Fleischer says current work on human breath to find 'marker gases' for a range of diseases could have huge potential for a non-invasive, user-friendly detection system based on nothing more than a quick breath test.

He cites the work of Israeli chemical engineer Hossam Haick, who has developed an artificial 'nose' that detects a range of cancers by picking up disease markers that move from the bloodstream into the lungs and get exhaled.

More recently, a team at Imperial College London and the University of Vigo in Spain unveiled a super-sensitive test that can pick up these markers in the extremely low concentrations associated with the very early stages of an illness.

The sensor can find the biomarker linked with prostate cancer, known as the Prostate Specific Antigen, using tiny gold stars laden with antibodies that latch onto the marker when they find it in a sample. The reaction produces a silver coating on the gold stars that can be detected with microscopes.

Molly Stevens at Imperial, who led the research, believes the test could be applied to other conditions, including HIV.

Early detection and speedy diagnosis could be crucial in the developing world, particularly in African countries where healthcare networks and population records are less robust.

"A woman could have walked for a day and a half (to a mobile clinic) but then leave before finding out if her baby has HIV. Then you've lost them."

The new field of synthetic biology - the creation of biological 'parts' that don't exist naturally - is also providing spin-offs in disease detection.

Paul Freemont, also at Imperial, is being funded by the Bill and Melinda Gates Foundation to develop a cheap detector that can quickly check water samples for the parasite that causes sleeping sickness.

Tim Dafforn at Britain's Birmingham University is using synthetic biology techniques to develop a gadget the size of a pocket calculator that can detect E.coli in minutes, rather than the hours it takes using samples in a petri dish.

In Dafforn's system, the synthetic construct used in the device looks like a thin strand of pasta. It hunts down the E.coli bacteria and binds to it, like a meatball in a bowl of spaghetti, making it visible using a spectroscope.

(Editing by Ben Hirschler and Robin Pomeroy)

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