Even if you don’t wear a Fitbit yourself, you probably know someone who does. Most wearable health monitors of that ilk are designed to be worn as a patch, wristband, or headband. But some health indicators could benefit from being measured in other ways. Take, for example, body temperature. Measurements of body temperature through the skin can be skewed by environmental conditions. Other, more accurate measurement methods are invasive and not suitable for wearable devices. A team led by Ali Javey of the University of California, Berkeley, has now designed a device that can be worn over the ear like a headphone and uses an infrared sensor that fits in the ear to monitor core body temperature from the eardrum in real time (ACS Sens. 2017, DOI: 10.1021/acssensors.7b00247). The researchers used the device to monitor changes in core body temperature of a person riding an exercise bike. The device also has an integrated microphone and actuator, so it can function as a bone conduction hearing aid. Other sensors for real-time monitoring of heart rate, blood oxygenation, or brain electrical activity should be able to be incorporated in the same device, Javey and coworkers say.