I am hoping to build several small wireless sensors which measure
- relative humidity
- air CO2 concentration
- air alcohol concentration
and which connect to a cloud service for data visualization and logging.
I have been able to find projects which are close to what I need (linked below), but I am hoping to fill the following criteria:
a) miniaturization (eventually I'd like to get it the size of a lighter or something thereabouts).
b) low power (I'm hoping it will run for months on a small battery). It will be measuring data in a very small enclosure (less than a liter of air) and so it shouldn't affect the temperature too much in there.
c) low cost (ideally it would eventually be around 15USD or so, but initially I don't mind having something more expensive.
I thought I should ask here in case people have an idea what the best current tech would be to use.
Q0) I imagine someone already did this exact project already, if so let me know.
Q1) Should I use bluetooth for this, or are the wifi modules low energy enough to be used long term like this?
Q2) Should I use sensor packs like the TI Sensortag?
Q3) Should I miniaturize by using ATtiny?
Q4) What cloud data service would be best if there were say 10 of these sensors?