Brassieres have a lot of surface area compared to, say, a wristwatch, and since they're worn under clothing, they provide a great potential place to stash wearable health technology.
That's why a company called Cyrcadia Health has created the iTBra, which gives wearers a digital breast self-exam. While a woman wears the iTBra during one day a month, it looks for subtle temperature changes that may indicate tumors, and then transmits the information to her smartphone. Not only is the digital self-exam more convenient than a mammogram, it's also more comfortable, since the iTBra's technology means "no pressing, squishing, squashing or radiation," according to the company website [source: Cyrcadia].
Meanwhile, Microsoft researchers have developed another type of smart bra for weight control. It includes an electrocardiogram sensor to measure heart rate, and an electrodermal activity sensor to track perspiration. The Microsoft undergarment uses that data to gauge a woman's emotional state at any given moment, in an effort to detect shifts that might result in overeating. When the sensor activity get too high, a warning signal is sent to her smartphone so she can move away from the kitchen. Women, of course, aren't the only ones who sometimes struggle with their weight, so we might someday see a weight-control smart undershirt for men. But as of 2015, Microsoft had no plans to commercially produce this bra [source: Griggs].