Mobile unit

[minorsecond]

Do you think it would be feasible to create this as a mobile unit? I'm thinking something that you can stick in the water for a few minutes once a week to take measurements. You'd obviously want to change the recording interval to maybe 1 minute and take 10 measurements. Maybe a tripod-type system that could be placed in the water.

How long does this take to build? I'm going to be work on my thesis this summer and will have a team of 5 people taking measurements, so I'd need to build 5 units. Have you had any accuracy / reliability problems with those sensors?

[nbonfils]

Do you think it would be feasible to create this as a mobile unit?

Sure thing, you'll probably have to rework on some of the designs, but as long as you manage to build it with a light casing it will be easy to carry it anywhere (since the components are quite light).

You'd obviously want to change the recording interval to maybe 1 minute and take 10 measurements.

Yeah, it'll be just a small modification in the code, you could even make some light blink or produce a sound (by adding a speaker) when your 10 measurements are done !

Maybe a tripod-type system that could be placed in the water.

My initial design was meant for the system to be placed on the shore and the probes go in the water, but if you manage to design the casing in such a way that it holds on a tripod, why not (just take care that the current will not move or tip over or even break the system).

How long does this take to build?

It took me roughly 2-3 months with 1-3 afternoon + evenning per week building it, but once you have your final design ready along with all the components (homemade PCB and such..) ready, it will probably go much faster.

I know that I'd probably be able to build a second prototype in less than 1 week full time. Imo, it will take you some times to rework the design for this use case (tripod, light casing) for your 1st build, then the 4 other will go much faster since in the end it's quite a "simple" design.

One thing that will be really important for you will also be to find a suitable mobile power source (battery, solar panel ?) in order to power the rpi along with its sensors for the duration of your measurements (~10min shouldn't be too hard to achieve, if I understood correctly)

Have you had any accuracy / reliability problems with those sensors?

Not that I know of, as long as you calibrate them you should have realatively accurate measurement, juste keep in mind that if you use cheap ones as I did you'll probably want to check the calibration quite often to avoid surprises

I'm going to be work on my thesis this summer and will have a team of 5 people taking measurements

I am really glad to see that my work will continue with you, if you have any other questions, feedback or anything else I'd be more than happy to answer. Also I'd be interested to see how you'll manage this project, so it'd be awesome to get some news about it 😃

Also I don't know if this can be of any use to you but here are some links related to this project:
https://biodesign.cc/2016/05/10/field-visit-with-the-state-of-geneva/
http://wiki.biodesign.cc/wiki/Fixed_Sensor