There’s lots of data in your breath. And the Boston-area start-up Calibre Biometrics set out to harvest that information with a device that tracks respiratory and metabolic metrics in real-time. Together with the design firm Design 1st, they’ve created Calibre, a breath-powered fitness tracker made with athletes in mind that uses multiple gas sensors to measure the flow and composition of air that’s inhaled and exhaled. Through breath calorimetry, the device collects dozens of biometrics including oxygen intake, calorie burn rates, and the body’s nutrient usage. Also known as indirect calorimetry, breath calorimetry is used to measure the oxygen intake and carbon dioxide output that happens each time a person takes a breath.

How does Calibre work? While breath calorimetry has long been used in hospitals and elite sports labs, consumer applications that measure pulmonary gas exchanges have been few. The direct-to-consumer Calibre device measures the wearer’s oxygen in, carbon dioxide out, as well as respiratory flow and volume 50 times per second. These measurements are used to determine a variety of metrics, including the rate of calorie burning and the percentage of carbs burned versus the percentage of fat burned. Its makers say the device can even detect ketosis, which is when the body doesn’t have enough carbs to burn for energy.

The device connects to a companion app on the user’s smartphone, offering monitoring of daily activity and the effects they have on the body. The data that the app displays is considerable. With respiratory performance, this includes carbon dioxide production, breath count, volume and rate, as well as Vo2 max (the maximum amount of oxygen a body can use while exercising). For fuel and calorie tracking, the app shows an array of fat and carb-burning metrics. Plus metabolic tracking to offer insight into how daily habits and diet affect physical performance. And not just with recorded data; the app displays live feedback that the wearer can monitor while exercising, with a playback feature for later review.

As the Calibre device is worn over the mouth, wearability was a big issue with this wearable’s design. It had to be comfortable, durable, and aesthetically appealing enough for people to wear in public. Plus, it had to pack in a lot of tech; the device has a suite of pressure and gas sensors plus a clip-on wireless module. All with a consumer-friendly weight that a wearer can handle hanging on their face for extended periods; Calibre comes in at under 50 grams. Which is why Calibre Biometrics turned to Design 1st. Calibre CEO Udi Meirav says, “Design 1st is also a one-stop shop, including supply chain access. This latter part is fairly complex, but they’re well connected to a system of manufacturers for prototyping and mass production, and their ability to bring all of this to the table really helped deliver the product we envisioned to market.”

Like the first fitness bands, Calibre is aimed squarely at the low-hanging fruit of the exercise enthusiast market. However, the biometric measurements that it can produce will doubtless find applications in telehealth and remote patient monitoring in short order. We’ll be watching to see how this new device fares in the marketplace.