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Sensors quest continues

A project log for Portable environmental monitor

A handheld, battery powered, sensor array unit for environmental monitoring focused mostly on air quality using a global infrastructure.

Radu MotisanRadu Motisan 05/08/2015 at 19:203 Comments

I was hoping to have better luck by now with the sensors. I have sorted out the radiation sensors and I'm happy with the alpha and beta radiation solutions, but I am still trying to find a reasonable way for detecting various gases. Dust sensors are also quite big for the enclosure I am planning for these devices:

For gases, I have two options: affordable, low size semiconductor sensors or costly NDIR sensors. The semiconductor sensors use a lot of power on the filament and have a long pre-heating time. Considering this is a battery powered application, and that we might need to be able to turn some of the sensors on and off depending on the measurements we are interested in, using semiconductor sensors might be challenging.

The NDIR sensors are costly, in the range of hundreds of euros / dollars for a single sensor, and would usually target a single gas only. Their size is not small either. Due to these serious limitations, I won't be able to use NDIR sensors.

Still looking for alternatives.

Discussions

Radu Motisan wrote 10/30/2015 at 08:37 point

Dear Joakim,

Some time has passed, but amazingly, the BME680 finally got incorporated into this design. Thank you for the hint, it had a huge impact: http://www.uradmonitor.com/bosch-bme680/

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Radu Motisan wrote 05/12/2015 at 11:00 point

Thanks Joakim, for the valuable input! 

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Joakim wrote 05/11/2015 at 16:52 point

Have you looked at Bosch BME680? It features temperature, humidity, pressure _and_ gas (VOC) in a 3x3 mm tiny package (https://www.bosch-sensortec.com/en/homepage/products_3/environmental_sensors_1/bme680/bme680_2). I'm curious how the gas sensor performs, being such a tiny package. It's not out yet, but should be available soon.

Bosch already sells BME680's little brother BME280, which is the same except without the gas sensor (https://www.bosch-sensortec.com/en/homepage/products_3/environmental_sensors_1/bme280/bme280_1). It costs about $5-6, which isn't too bad for 3 sensors in one.

I bought Embedded Adventures' breakout board (http://www.embeddedadventures.com/bme280_weather_multi_sensor_mod-1022.html), and from my early testing the humidity and pressure sensors seem pretty accurate and response time is quick. The temperature sensor is optimised for low noise and high resolution, primarily providing temperature compensation for the other sensors. I haven't tested its accuracy, but at least its readings seems very stable.

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