You are squandering your visitors!
You purport to be encouraging students to get interested in agriculture by starting with aeroponics.
If you actually want to encourage people at the very least you should be providing some information. It would be very easy to ask for volunteers to improve your site and wiki, but you could also run some competitions for various designs eg as below
However you have an appallingly uninformative website which redirects interested visitors to the even more obscure github. You haven’t even pinned important topics to the top of your forum! I’m actually shocked at how bad your website and design is, especially as you claim to be trying to get schools interested and you’re in MITs media lab.
For those who give up wasting their time with your website and search the web for “aeroponics for beginners” they are directed to a wealth of information helping them grow marijuana, so I’m sure most parents are going to be really keen to let their children start that!!!
You should be asking your visitors to contribute to the wiki and providing information on:-
*Simple aeroponic nutrition:
Why might you buy a commercial mix to start with and what not to get.
But optimal plant growth seems to require varying quantities of nutrients at each phase of growth. It should therefore be easier to modify and experiment (and cheaper) to work with provide a recipe so you can just mix up separate bottles of nitrogen, phosphate and potassium compounds and a micronutrient mix. You could then put them in separate syringes and use continuous rotation servos to automatically inject appropriate amounts into the mix as required ($2 for servo and 5mins to modify and a further 5mins to assemble into a functional automated syringe). This would be a great school project as it could involve measuring and mixing and chemistry, and some basic mechanics/electronics…
Searching google for “hydroponics nutrient recipe” seems to give a few starting ideas, but the mixes don’t quite provide this flexibility (and should aeroponics be different?)
Discussion around a beginners optimal setup.
What are good values for humidity, temperature, etc with reference to a simple “recipe” (don’t bury it in a database if you want people to be interested).
Don’t forget the importance of light - start by putting it on a window sill, but really whats wrong with using a desk lamp (as most people have one that would seem like a good place to start), but an LED fluorescent bulb can be had very cheaply now, or what about those colour changing LED strips, … (you get to teach about physics, economics, and botany simultaneously…)
What about EC and pH
What do you sacrifice by not controlling the leaves environment (ie having plants grow in room air)?
Then what changing CO2 and O2 contribute (and perhaps a discussion of tight vs loose root bundle promotion)
Stress usually makes leaves bitter (try tearing bits of a lettuce and see what it tastes like a few days later). Can you explain how to makes it sweeter?
And when the basics are there I’m sure there are a bunch of people out there who would like to try a java simulator to experiment/design/upload growing recipes too…
You should also have various aeroponics setups (with photos) - you could run competitions to get hobbyists designing these:-
*The simplest ever aeroponics setup (I think this would growing spouts in foam, but what else can you grow and eat with little or no effort?) What about growing a new lettuce from the base of an old one - although this is probably the simplest hydroponics setup it’s still a fun experiment.
*The 2nd simplest aeroponics setup (I think this would be just an icecream container and a fogger). This would get families interested if they could produce a lettuce or cucumber every week for a $5 outlay (plus nutrients - would it be possible to use fluid from composted food, or blend another vegetable and use the juice as a basic nutrient solution to make it even simpler?)
*The coolest: I’m imagining a usb powered aeroponic ‘plant pot’ which could be monitored from a tablet, that would be a tech-toy to get people interested. A dome could be made from the bottom of a soft-drink bottle, and blue/red LEDs would add extra coolness. DIY version $10-15/pot. (mine would definitely be used for growing everbearing strawberries)
*A reliable home vege factory - this should be able to simultaneously be able to grow a range of different veges eg strawberries (what wouldn’t get most kids interested), lettuce, cucumber, some herbs. Thus it probably needs 6-12 individually controlled growing locations to guarantee a continuous supply of vege. It would probably be best if it was low-profile and could sit on a window sill.
*A home research version, this could include more advanced tools, such as a simple weighing system to measure growth, or an RPi to monitor leaf density
On that note, I’m not sure why you are mucking about with Raspberry PIs, as very few people own them, and unless you’re using a webcam to monitor leaf colour or foliage density (which most people won’t need) they’re total overkill (and most people already have webcams/tablets/old phones which could do this anyway).
Arduino nanos can be had for around $2, and are more than capable of running and monitoring an aeroponics factory (after all the variables don’t change that fast), and for that price you could easily have one for each plant. If you want to link via I2C and add a bluetooth board for another $2 you can communicate with an Android tablet using MIT inventor and teach the basics of programming too. But seriously it is a cakewalk nowdays to have a generic host which runs on Android, IPad, PC, Mac and Linux and would easily graph values and modify recipes!!!
BTW an arduino can easily measure EC/TDS of a fluid for a few cents - if you are only measuring intermittently then DC measurements should be fine, but add a cheap H-bridge and you could easily switch to AC though.
Why don’t you just use stainless electrodes sitting in the fluid. If they corrode/coat then, put them in a small reservoir with a hole in the bottom. A $2 pump could fill this every 5 or 10 minutes (depending on how often you wanted to measure), the measurement could be made and the fluid would then drain away.)
What about use a simple piezo disk under each plant with a driver on the main circuit board. If this were possible you could have a disc under each plant to drive the fog into the root bundle
Or use a USB fogger so the peizo disk is separated from the electronics and the voltage/current remains low thus minimising/ avoiding use of multiple voltages in the system.
eg ebay item 401132954396
What about asking for novel designs for subcomponents rather than designing your own - there are hundreds of hobbyists around the world who like experimenting with stuff (that’s why Reprap really got going - Adrian got them involved early)
To separate the root bundle, what about a mesh cone. Place the seed at the tip and the roots grow outward and drop through the mesh to prevent too tight a root bundle (you could cover this with black plastic and place it over the peizo.
What about suspending the setup from a spring so you could measure the weight of the plant - you might even be able to use induction to measure the harmonic frequency and infer it from that rather than a sophisticated scale.
What about discussing the various pros/cons of humidity sensors in aeroponics eg resistive vs capacitive vs a laser/photodiode (all possible for consumers for $1-$2)
for pH: what about the redox principle of a lemon battery - this uses different electrodes (typically a galvanised (=zinc) nail and a penny(=copper)) to chemically generate a voltage from acidity in fruit. I would have thought this should work for any liquid solution enabling an arduino to measure the voltage for a cheap pH meter. (Obviously you would have to measure the EC first with identical electrodes then correct for changes in the ions in the solution). With these components you could easily replace/clean the electrodes or you could get a carbon electrode by cannibalizing a AAA battery.
You also need someone sensible to sort out your github. You only need 4 files in your root directory for the food computer:-
- the compiled host ready to install
- the arduino source code ready for compile/upload
- a bill of materials for the electronics
- graphic for the basic breadboard design
everything else can be put in a subfolder so as not to confuse the interested newbies