A Beijing-based medical device company called Raiing has been granted 510(k) FDA clearance for the Raiing Wireless Thermometer, a peel-and-stick contact thermometer sensor that continuously transmits body temperature readings to a companion iPhone app, which is already available in the iOS AppStore. The app is called Vitals Monitor and is currently available for a free download, but the device itself does not appear to be commercially available yet.

The device, which is worn under the armpit, uses Bluetooth to transmit data in real time to the iPhone, according to Raiing's website. The thermometer can also store up to 72 hours worth of readings According to the FDA filing, the device is battery-operated, reusable, and intended for use by ages 2 and up.

The 510(k) document doesn't give any specific indication of the use case the device is cleared for, except for the age restriction noted above. However, the app can alert users when the thermometer hits a preset temperature, which could be useful for parents monitoring sick children, the use case Raiing promotes on their website.

Of course, thermometer apps for non-medical use have been around for a while. For instance, the iGrill cooking thermometer was an early iPhone accessory, and more recently the iCelsius was released for detecting ambient temperature.

Lately, a couple of companies have been pursuing infrared body temperature thermometers, which detect the intensity of infrared light that naturally emits from objects. Medisana's Thermodock and CellScope both intend to leverage that technology, but neither has been cleared by the FDA. Just this week, Forbes reported on a patent filing for another infrared thermometer app, from the Fraden corporation.

Raiing's contact thermometer appears to be the first smartphone-enabled body temperature thermometer to secure FDA clearance.

As a wireless patch that monitors continuously, the device is more similar to Cambridge Temperature Concept's Duofertility device, than anything else on the market. Duofertility, which is 510(k) cleared for use as a conception aid, tracks women's ovulation cycles by constantly monitoring body temperature.

The thermometer will be Raiing's first product, but the app's description in the AppStore mentions "Raiing wireless health monitors," suggesting the company has other devices in the works.