THE spectacular precision of a newly designed body temperature sensor has shown the way to many applications in the medical field - especially in developing a device to help women to get pregnant.

The wireless sensor - from UK company Cambridge Temperature Concepts (CTC) - can measure body heat to within a thousandth of a degree; up to now, solutions have precision of a tenth of a degree, typically.

"The various technologies that we have used to create our sensor did not exist 5-10 years ago," said Dr Shamus Husheer, CTC's chief executive officer. "Companies had basically given up trying to create sensors with a high precision for consumer use. Fortunately, as a bunch of recent graduates, we didn't know it couldn't be done. Also, being a start-up [company] meant we had to use ingenuity to solve problems."

The small sensor's high degree of accuracy and long life are key to the company's first commercial product, DuoFertility, that is designed to inform couples of the optimal time to try to conceive a baby.

When an egg is released, the woman's body temperature increases by about half a degree but this is easy masked by variations that naturally occur by walking, sitting up, and so on. Therefore, the recommended method is to use a thermometer to take a reading early in the morning just after waking and before getting up.

A spokesperson said: "This is inconvenient and has to be manually recorded, charted and then interpreted to try and determine exactly when the temperature change has occurred. Often, it is not clear for a day or so, by which time the best time for conception has passed.

"By contrast, the sensor's temperature readings taken every few seconds are statistically processed alongside additional physiological parameters, and compared with previous readings from other women who have similar patterns to predict the optimal time for conception a few days ahead so that couples can plan for a romantic evening."

The incredibly precise temperature measurements allow calculation of skin surface heat flow and which in turn allow calculation of core body temperature.

This, combined with a movement sensor, can indicate when the user is in deep sleep and when unconscious movement occurs, causing more blood to circulate and disturbing the body's thermal equilibrium. The result is data giving a dramatically improved measurement of body temperature during deep sleep and which is precisely what is required for the accurate detection of ovulation.

"We are currently in the middle of a user trial," added Dr Husheer, "and we are getting tremendous feedback from users. They really love the prediction element, for it enables them to plan ahead and relax rather than stress and worry about whether they have got the timing right from their reading of the points on a graph.

"It is also tremendously rewarding as the trial is with couples who have problems with having babies and are contemplating or have undergone expensive IVF treatment. We have already had couples on the trial becoming pregnant. Basically, we are enabling them to have the best possible shot at getting pregnant the way nature intended," he added.

The coin-sized unit also uses innovative power-saving techniques to extend the battery life to in excess of six months rather than the usual life of a few days.

The sensor can process and compress the temperature readings that are taken every few seconds. As much as a month of data can be stored on the on-board 2Mbyte memory that is downloaded via RF by a reader when required.

The Cambridge Temperature Concepts company is based in the Cambridge Science Park, southern England. It was founded in 2007 and its first commercial product, DuoFertility, took only 18 months from seed funding to product on the market.

The company is investigating other medical uses for its sensors, such as infection response monitoring in which the ultra-sensitive temperature readings can open new treatment regimes.