Hey interesting thread here.
Seems like a lot of people have some great ideas on this. My 2cents is its a really difficult area – specifically for what Rene has pointed out – the quiescent current.
Unfortunately Arduino does not cultivate a low power paradigm – Arduino core has said dealing with low power event based software is too difficult, but PRJC.com is a step beyond the core.
I’ve got a solution for stream monitoring that I’m working up –
http://www.meetup.com/Nerds-For-Nature/photos/26131259/#437612397 which I talked about at this years San Mateo Maker’s faire – see the poster to the left of guy/me – “Wireless Stream Sensor Road Map”
For anybody who is interested in a working on a Specific Conductance probe I created this as a starter.
The electrodes could be titanium – the challenge is how to plan to clean the electrodes of the ever prevalent slime build up.
Some instruments have a wiper, but I haven’t figure out how to easly do this.
Slime is often watershed dependent but a physical cleaning seems to be the most obvious solution.
I could produce some hardware using the Teensy-LC to aid in prototyping if anybody is interested.
What is taking most of my time right now is a low-cost water depth probe, with a place holder here
which can run by itself data collecting, or plug in to a low cost
Wireless Sensor Network
It uses a basic processor, Teensy-LC
low power MKL26Z with LiFePO4 battery, solar charging and RS485/SDI12 –
initially with a water depth measurements,
and can fit into a 2″ PVC pipe for protection and sealing in a stream.
There is a few places discussing this … so I’m wondering whats a good way of promoting the evolution of specifications for instruments.
with plug’n’play – it will fit into a 3″ plastic pipe for easy protection, solar powered/LiFePo4 and based on a Kinetis Arm (similar to the Teensy3.1 but because of hardware port limitations actually another processor with 128Kram)
So the challenges can be broken into smaller challenges – then they can be solved one-at-a-time.
I wonder if anyone is trying the Teensy3.1/TeensyLC (with Freescale ARM M0 processors) ~ solidly Arduino in a workable footprint.