BME 280

[aparab]

I'm a graduate student at UC Davis. My research team is working on building a wearable device that monitors human vital signs. We are strongly considering choosing the BME 280 sensor for this project to calculate Total Evaporative Water Loss and Skin Wetness factor, but we would like to understand more about this product. Can someone please help us with these questions:

1. What is the recommended point of contact for the most accurate sensor readings from human skin?

2. For the accuracy values in the datasheet, can you elaborate on how your team reached those values? (any testing or research)

3. Does the accuracy of the device change in the case of a buildup of sweat or any moisture?

Can you please clarify these points for us so we can get a better understanding of the sensor? We greatly appreciate your help and look forward to hearing from you!

Thanks!

[FAE_CA1]

Hi,

Thanks for your inquiry. Please see my comments to your questions below.

1. What is the recommended point of contact for the most accurate sensor readings from human skin?

>>> Unfortunately we did not do research on this topic. So we don't have recommendation on the point of contact for the most accurate sensor readings from human skin.

2. For the accuracy values in the datasheet, can you elaborate on how your team reached those values? (any testing or research)

>>> Each BME280 sensor is calibrated, trimmed and tested in the chamber in Bosch factory before shipping to the market. Each BME280 has its own calibration parameters stored in its NVM for future humidity calibrations from raw sensor readings. The accuracy values in the datasheet is from our characterization test results from multiple BME280 sensors.

3. Does the accuracy of the device change in the case of a buildup of sweat or any moisture?

>>> BME280 has a vent hole on the top of the sensor. If sweat or moisture gets into BME280 sensor, then the accuracy will be affected. You may consider to use a piece of Gore membrane for example GAW113 at
https://www.gore.com/sites/g/files/ypyipe116/files/2017-01/GORE_PEV_DataSheet_AcousticVents_Dust_Spl...

to cover the vent hole of BME280 or the hole of the enclosure of your product to prevent any liquid from getting into the sensor.

Thanks.