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COMMUNITY : FORUMS : BURNING QUESTIONS


A custom timed release liquid dispenser....

Hi everybody! How are we all?

I'm working on my latest project sending a weather balloon to around 100,000 feet and capturing the journey on camera. I've done it before as you may see on my blog www.joshingtalk.com.
Anyway, my newest project involves making art at around 100,000 feet and this is where you could help!
I know this could be done fairly easily but I do not have the knowledge to do it.

I need a container that dispenses a small solution of liquid every 15 minutes. Now I've done a lot of research and this is the best I can come up with:
http://www.amazon.co.uk/Fishmate-Automatic-Aquarium-Fish-Feeder/dp/B000YK5W18

It's gravity action, many compartments, on a rotary basis, at timed intervals BUT it will only allow for a few rotations over several hours. I'm looking for 8 rotations over 2 hours.
I also checked out water timers but they seem a bit more complex.

Maybe you have an alternative idea? Maybe it's 5 minutes of fiddling for you? It feels like to the right person, this should be fairly easy to overcome.
I'm based in the UK and if you would like to help me with this project, I'd love it and be really appreciative! It's all good fun and you could see your device hovering at 100,000 feet....
Many thanks,

Josh

Update- Another vital thing I forgot to add is that this device needs to weigh under 200 grams.

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4
ddemayo says: Jun 29, 2012. 2:00 AM
Keep your syringe and just hook a screw with a small motor to the syringe set to a timer. it would be light weight and simple to build.
JoshingTalk (author) in reply to ddemayoJun 29, 2012. 2:16 AM
Thanks ddemayo! So many things that could be done with this! Should be fun....
cdslashetc says: Jun 26, 2012. 5:16 PM
I've been mulling this over and I had a thought: What about something like 8 spring-loaded syringes with triggers? I take Humira, which comes in something like an EpiPen, that's where I got the idea. In practice I don't picture an actual EpiPen, more like a plastic liquid syringe in a cylinder with a spring behind it, the spring is retained by a cotter pin, something pulls out the pin allowing the spring to depress the plunger. A very small amount of power would be needed to pull out the pin it could probably be done with a servo that would require less power than an actual pump and less weight since all the power to dispense the liquid is basically stored as potential energy in the springs. The down side is you need 8 syringes, but each could contain a different color, altogether it would probably be lighter than having 8 peristaltic pumps or some sort of manifold to dispense different colors.
cdslashetc in reply to cdslashetcJun 26, 2012. 5:31 PM
If you hate needles you might not want to watch this, actually you don't even see the needle, it's more the suggestion of it.  This isn't me (obviously) the Humira pen has a small trigger on the back it takes a small amount of pressure to set it off, then a spring inside pushes the syringe.  A trigger like that could be set off easily with solonoid, or a cam on a servo could set off multiple syringes in sequence.

Humira pen injection

I was hoping to find a video of someone disassembling one to show the spring but no luck so far.  The Humira pen is only 0.8cc, but I figure you could do at least 10cc probably more, the trick will be finding a syringe that requires as little pressure as possible.  Come to think of it, a motorized pipette would be another option, but they tend to be expensive.  If the liquid is low viscosity, you could use a regular pipette with a stopper in the top just using suction to hold back the liquid, pull the plug and the liquid flows out through the tip by gravity, that would be cheap and lightweight if you use plastic pipettes.  I bet that inkjet ink like from a refill kit could work.
cdslashetc in reply to cdslashetcJun 26, 2012. 5:44 PM
Awesome, 20cc spring-loaded tree syringe, the red handle is only for loading because that is when you retract the spring, retaining the syringe to the withdrawn position could be tricky, though.

Chemjet tree injectors
JoshingTalk (author) in reply to cdslashetcJun 27, 2012. 8:14 AM
Hi cdslashetc,

Really cool ideas. I like the thought of the spring loaded mechanism. Off a timer, it could function really nicely however, you cracked what I already have! A few pipettes and a bit of help from gravity, we are refining the liquid solution to be quite thick therefore giving us a drip to calculate how much liquid it can dispel over time.
Maybe best to stick with simple but effective for now but interesting concepts nonetheless for future projects!
Thanks again,

Josh
13
Jason Bedard says: Jun 23, 2012. 6:58 AM
The paristaltic pump option steveastrouk suggested is your best option. The timining can be controlled by a simple 555timer circut. The whole thing will be very light and low power consumption. Paristaltic gives ultra fine control of the medium you are pumping.

I would send you a pump and driver board but I fear the shipping will cost more than what you might pay locally.
JoshingTalk (author) in reply to Jason BedardJun 23, 2012. 7:18 AM
Hi Jason! Many thanks for your comment, I have done a bit of research on the peristaltic pump and part of me thinks it would be a little too heavy or big but then again part of me wants to use one! Thanks for the offer to ship it over but I understand that it could cost a bit of money.
I'll have a think about the options we have in the UK and thanks for the 555timer suggestion. Will research that too!
13
Jason Bedard in reply to JoshingTalkJun 23, 2012. 7:28 AM
You might be looking at a larger pump setup. What I am most familiar with is used in medical equipment and is quite small. Approximatly 1.5cm*2cm*4cm.

I'll send a picture later this morning (I'm in GMT/UTC -7)
JoshingTalk (author) in reply to Jason BedardJun 23, 2012. 8:24 AM
Oh that would be wicked! Thanks Jason. My email address is: joshingtalk@gmail.com

Cheers!
13
Jason Bedard in reply to JoshingTalkJun 23, 2012. 10:24 AM
Ok, so I was wrong about the pump. It is significantly bigger and runs on 120VAC. However, another solution is a solenoid pinch valve that only needs 3.6VDC and is very close to the size I noted above. Attached are some photos.

The fluid supply tubing runs through the aluminum cylinder with the two slots.

One way to load the paint would be in a NG (Nasogastric) bag (see link). This is much like an IV bag but can be filled and refilled. Should be readily available from most medical suply stores.  http://www.medwrench.com/?equipment.view/equipmentNo/3174/CORPAK-Medsystems/Polar-Enteral-Feeding-Bags---Set/
Note, the URL to the medical website was just the first one in a google search, not one I necessarly recommend.  Check locally for this item as most urban centres have such suppliers.

Just some ideas.  Not sure how any of this might function at high altitude.  Atmospheric pressure would be different as would opperating temperature.

pinch valve and controller.JPGpinch valve close up.JPG
JoshingTalk (author) in reply to Jason BedardJun 25, 2012. 5:13 PM
Hi Jason! Thanks for your time to reply and sorry for the delay in writing back.
It's a lot to think about but definitely a cool idea. I wonder if maybe for now I'll keep the concept simple and potentially do something bigger on another launch.
Would be interesting to see the results for sure. I'll keep pondering it.

Thanks again,

Josh
14
steveastrouk says: Jun 20, 2012. 10:01 AM
Peristaltic pump, off, Ebay, 20 quid.
49
lemonie in reply to steveastroukJun 20, 2012. 12:08 PM
A syringe-driver* might be better.

L

*Insulin/morphine-pump.
JoshingTalk (author) in reply to lemonieJun 20, 2012. 1:38 PM
Cheers Lemonie! Will do some research. :)
JoshingTalk (author) in reply to steveastroukJun 20, 2012. 10:37 AM
Hey! Thanks for the suggestion....one kinda vital thing I forgot to mention, is that weight is an issue. I need a device that would be 200 grams or under.
Maybe this could work? I'll look into it a bit more.
Thanks again.
14
steveastrouk in reply to JoshingTalkJun 20, 2012. 10:52 AM
Easy
JoshingTalk (author) in reply to steveastroukJun 20, 2012. 11:14 AM
Is it possible to get these units with a timer on them? Would you suggest any other mods to the pump?
14
steveastrouk in reply to JoshingTalkJun 20, 2012. 11:41 AM
You'll have to make a timer.
JoshingTalk (author) in reply to steveastroukJun 20, 2012. 12:39 PM
Ok thanks! Will have a look but that might be beyond my skill set.
Thanks anyway.
14
steveastrouk in reply to JoshingTalkJun 20, 2012. 12:39 PM
What's the mission?
JoshingTalk (author) in reply to steveastroukJun 20, 2012. 1:38 PM
I'm trying to create one of, if not, the first pieces of art in near space, around 100,000 feet.
I've got some chemists working on a decent solution so it can withstand the properties of the atmosphere up there.
Just figuring out an alternative solution release other than gravity. It will be falling and filmed from a payload, below 30cm onto a white canvas, trapping the solution.
Hopefully combined with the curvature of the Earth in the background! :)
Should be good!
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