U.K. Startup Sees Pregnant Opportunity

The user can also plug the handheld into her computer using a provided USB cable, then download the data onto DuoFertility software to produce charts detailing her ovulation markers and fertility levels over time. She can utilize this software to produce specific charts for a doctor or fertility counselor, as well. Connecting the reader to a computer also recharges its battery.

The systems uses a 125 kHz RFID tag and sensor, in conjunction with a handheld RFID interrogator.

"The key advance in our product was getting the power consumption of the sensor to below one microamp, on average," Husheer says, because this provides a long life for the sensor. The sensor can operate for several months on its lithium battery, which can not be replaced or recharged; it uses an 8-bit microprocessor to process and compress the temperature readings, which are taken every few seconds. Up to a month's worth of data can be stored in the module's 2 megabytes of memory. Because it relies on a passive RFID tag to transmit the information to the reader, the module's battery is not necessary for data transfer, and this helps extend its life.

Due to the application's large data transfer requirements—up to 2 megabytes of data being collected from the module—Husheer says CTC could not use any existing RFID air-interface protocol that tags and readers employ to communicate with each other. Instead, he notes, the firm designed an air-interface protocol specifically for the DuoFertility application.

In addition, the data transmitted between the tag and interrogator is encrypted. "A cryptographic key exchange is done between the tag and reader at the factory," Husheer states, "before the package is shipped." This ensures that only the module and reader that are shipped together can be utilized together, and prevents an unauthorized third party from using a different reader to collect data from the module, or to eavesdrop on the RF transmission. If the woman damages or loses the original module, she can order a new one and then, through DuoFertility software, create a new set of cryptography keys online that will pair the replacement module with the handheld reader.

The DuoFertility kit is sold online, for £495 ($807). CTC is now working on additional RFID-based temperature sensor systems for medical applications, Husheer says. These include a take-home system designed for detecting fevers that could signify an infection in patients who have undergone outpatient surgery.