Through perspiration we are constantly losing water over the surface of our skin, which has an influence on the state of hydration on our body. The lost water needs to be replaced by drinking. Especially elderly people are prone to dehydration because the water content in the human body is decreased with increasing age. Based on research papers about hospitalizations due to dehydration, more than a half a million cases per year were registered. The potential savings if those hospitalizations and the associate costs could be avoided are more than a billion USD. One possible way to address this problem is to measure the perspiration rate.

This is where Sensirion’s humidity sensor SHTW2 comes in. With two SHTW2 sensors arranged in the right way, it is possible to measure the perspiration rate accurately. The constant transpiration, which is nothing else than evaporation of water through our skin creates a gradient of absolute humidity. This gradient is actually proportional to the perspiration rate. What we need to measure are two sensors which are placed in some kind of channel.

On Sensirion’s developer website we published tutorials, implementation instructions as well as sample code to calculate the rate of perspiration. Get inspired by visiting developer.sensirion.com/perspiration. To build your own smart watch, which can be equipped with Sensirion’s humidity and temperature sensors enabling perspiration measurement, please have a look at developer.sensirion.com/wdk-build-your-device.