Sensor accurately measures body temperature

The coin-sized unit also uses 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's precision and long life open up many applications in the medical field.

It uses a microchip PIC 8-bit microprocessor to process and compress the temperature readings, which are taken every few seconds.

Up to a month of data can be stored on the on-board 2Mbyte memory, which is downloaded via RF by a reader when required.

Average sensor power consumption is less than 1uA, providing for months of continuous use from a tiny battery.

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

When an egg is released, a woman's body temperature increases by around half a degree, but this is easy masked by variations that naturally occur by walking, sitting up and so on.

The recommended method is to use a thermometer to take a reading early in the morning just after waking and before getting up.

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.

The precise temperature measurements allow calculation of skin surface heat flow, 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 greatly improved measurement of body temperature during deep sleep, which is precisely what is required for the accurate detection of ovulation.