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An Environmental Sensor

The sensor market is highly fragmented. Many sensor companies are good at one or a few sensors based on super-secret ways they have of building them. When combining with other sensors for things like IMUs, they may actually bring in partners for sensors they don’t make themselves, and they may use sensor fusion software from yet another company.

Bosch Sensortec has been taking a different tack, however. As one of the two really big sensor guys, it’s taking the “you don’t need anyone else” approach, doing a wide variety of its own sensors and writing its own fusion code. And, for those that don’t want to customize and optimize the code, they then combine them into complete units that abstract the lower-level stuff away. They refer to these as application-specific sensor nodes (ASSNs).

The first of these was their orientation sensor. And they’ve now announced another one: an environmental sensor, the BME280. It combines pressure, humidity, and temperature sensors. Yes, it pretty much looks like a weather station in 2.5×2.5 mm2 package. Although they say that it has application for fitness as well. And, in fact, they’re touting the pressure sensor as providing an altitude response for indoor navigation (even thought that would seem to be a better fit for the orientation sensor). Its accuracy for that is ±1 m, enough to discriminate floors in a building.

One thing they’re particularly proud of is the humidity sensor. While typical versions take 5-10 seconds to register a value, they can tap the humidity in less than 1 second. They do this using a polymer that absorbs water; when it does, it changes its dielectric constant. Apparently the variables in this physical structure – the choice of polymer, mode of access, layer stack, and thickness – all affect the diffusion time both in and out. (Yeah, after you’re done measuring the humidity right now, you need that water to leave if the outside humidity drops.)

Because it’s in a ported package (the outside air has to get inside to be sampled), they also see this as lending itself well to future gas sensors. So there may be more to come here.

You can read more about the BME280 in their announcement.

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