A newly-published patent application describes a method for Apple Watch sweat measurement, which could provide useful data to athletes, as well as guiding fluid intake after exercise.
The patent describes how perspiration measurement could be automatically triggered when motion sensors suggest the wearer is exercising …
Why measure perspiration?
Perspiration measurements can be used in a wide variety of ways. For example, breathalyser machines used to conduct roadside sobriety tests measure the amount of alcohol present in water vapor, which is a good proxy for blood alcohol levels.
There are also medical tests which measure the concentrations of other substances in the body via sweat. For example, measuring sweat chloride levels is considered the gold test for cystic fibrosis.
But on a more everyday level, simple sweat volumes can provide data on physical fitness. While some mistakenly think sweating is a sign of poor fitness, studies show that as you build physical endurance, you sweat sooner and more heavily than average because you have a higher maximum oxygen uptake, and your body is working harder. Sweat glands also get trained by fitness regimes, and become more efficient over time, allowing you to sweat more and thus remain cooler when working hard.
(Overweight people sweat more for any given exercise level, but that’s because their body is doing more work in moving a greater mass: That’s a function of weight, not fitness.)
It’s also useful to measure fluid loss via sweat, so that you can hydrate appropriately both during and after exercise.
Apple Watch sweat measurement
Apple’s patent application (spotted by Patently Apple) describes how sweat measurement could be added to a “wearable device” whose illustrations clearly indicate an Apple Watch.
Embodiments are directed to devices, systems and methods for determining a perspiration metric of a user. In some embodiments, a device may include a perspiration sensor having first and second electrodes positioned on a skinfacing exterior surface of the device. Capacitance circuitry may measure a capacitance between the electrodes, which may be used to calculate the perspiration metric. In some embodiments, the device defines a cavity such that one or both of the electrodes extend at least partially into the cavity. Other embodiments include a second perspiration sensor, and measurements from the second perspiration sensor may be used in calculating the perspiration metric.
We naturally add our standard disclaimer here: Apple patents a great many things, and only a small percentage of them make it into products. Right now, the company is having enough trouble trying to hang on to existing Apple Watch sensor capabilities …
Photo by Chander R on Unsplash
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