Syringe Pumps - Peristaltic Dosing Substitute & DIY Aeroponics


#1

Has anybody considered using syringe pumps for better control over dosing? DIY syringe pumps using 3D printing and other fabrication methods seem to be popular among people setting up low-budget biology labs.

Having watched the discussion here on the forum for most of the last year, it sounds like the peristaltic pumps in the BOM move fluid too quickly. People seem to be having trouble with achieving small, carefully controlled doses. I haven’t tried it myself. But, from what I see in people’s syringe pump videos, that route might be an easier way to get really good dosing control.

There are a couple syringe pump configurations you can use:

  1. Manual refills: Use a regular syringe with a tube on it, and have a person fill it manually. Your machine just needs to squeeze the plunger at a controlled rate and detect when the syringe needs refilling. This looks good for moving small amounts of fluid slowly and gradually.

  2. Continuous pumping: Instead of just a tube on your syringe, use the valve from a “Cornwall syringe”, or build the equivalent from a couple check valves and a tee joint. The Cornwall syringe configuration would draw liquid from one tube when your machine pulls the plunger and expel liquid through the other tube when your machine pushes the plunger.

Here are some of the good links I found by searching for “DIY syringe pump”, “syringe servo”, “3D printed syringe pump”, etc.:

  1. http://fab.cba.mit.edu/classes/863.13/people/wildebeest/projects/final/index.html
  2. https://www.youtube.com/watch?v=-81ECglkDqA – “Syringe injector (10cc with 180deg servo)”
  3. https://www.youtube.com/watch?v=TH8st3B_bd8 – “Arduino controlled aquarium dosing pump”
  4. http://www.instructables.com/id/Simple-Syringe-Pump/
  5. https://hackaday.com/2017/02/26/diy-syringe-pump-saves-big-bucks-for-hackers-lab/
  6. https://www.youtube.com/watch?v=LK7IJcSUMkM – “DIY Syringe pump” (this shows the valve from a Cornwall syringe)
  7. https://depts.washington.edu/soslab/turbidostat/pmwiki/pmwiki.php?n=ConstructionManual.SyringePump

#2

I have but I chose to go with a stepper motor driven peristaltic pumps instead. They are incredibly precise and cost around $25-$45 CAD each.

There are DIY stepper motor driven syringe pumps but is a lot more work. If you are wanting it to measure what was actually dispensed then you can just use a graduated container with any pump.


#3

@Ya3ny, Thanks for mentioning the stepper motor peristaltic pumps. I hadn’t seen those before.

@Webb.Peter, I came across a way to extend this syringe pump idea that might be useful for aeroponics. It turns out there are a few different types of aerosol drug delivery devices with Luer Lock fittings for attaching to a syringe. In particular, the MAD Nasal™ Intranasal Mucosal Atomization Device is marketed as generating 30-100 micron particles. That overlaps well with the 5-80 micron range that atom recommends for HPA.

I’m wondering about the possibility of making an HPA mister from a 1mL syringe with a Cornwall syringe valve and a MAD atomization device. Instead of pressurizing a big accumulator and using a solenoid valve, it might be possible to use a servo or stepper motor to push and pull the syringe plunger. I’m envisioning a potentially very cheap, quiet, and compact desktop aeroponic system that would be suitable for growing a small number of plants–good for developers or people just getting started.


#4

I like the approach - good idea about the nasal vaporizers. I’ve had similar thoughts using air fresheners (the dosing is relatively consistent/accurate).

You’d have to make the chamber much larger - the one you linked is about 3 ML. How would you refill?


#5

Syringes with a small plunger surface area can develop a fair amount more pressure relative to larger size syringes for the same amount of force applied to the plunger (because physics). Adding a two way valve–see link above about “Cornwall syringe”–can make a syringe work like a bike pump. @atom’s post linked above recommends “no more than 1ml of liquid per 100L of root chamber volume” per misting, so–potentially–a good misting cycle might go something like pull 3 mL, push 0.5 mL six times separated by appropriate delays, then start over with another 3 mL pull.

For context on syringe pressure, I found some pdfs for Medline cardiology kits (syringes, tubing, stopcocks, manifolds, waste bags, etc) that refer to low pressure as 45 PSI, medium pressure as 500 PSI, and high pressure as 1,050 PSI! The syringes for the kits range from 3mL to 30mL, but–judging from the pictures–around 10 mL appears to be what they expect people to use.

[edit: Actually, 0.5 mL per misting would probably be way too much for a desktop system. By my math, 1mL/100L comes to about 0.03785 mL per gallon. So, supposing you used a 3 gallon aquarium as a root chamber, you’d need to mist less than 0.11mL at a time. With a 1 mL syringe and a worm drive stepper motor syringe pump, that might be totally reasonable.]


#6

Thanks Will for dumbing it down a level for me. I love this idea. What an accurate way to assure dosing quantity (timing will always be futsy).

I’ve reached out to several other people I know who may have valuable input. This is exactly the kind of solution I’ve been hoping existed.

If you wouldn’t mind - it would be helpful to have a drawing I think (real quick on paper works fine).

@Atom @juan1 @adam @yusuf.khan.su @Jlniemi @estorhok @seiche @Puxi


#7

Hi all, I’ll try a small contribution here: Despite you can achieve good accuracy and pressure, I’m not so sure about the reliability of such solution. In fact such syringes aren’t generally designed for 1000’s of cycles, think that I believe is important in such a project. If you go to more reliable syringes, the price will rocket high very fast. I’m also not 100% convinced by the “rule of thumb” given to be about 1mL / 100L volume of recipient. My experience (and physics) tell’s me that also the surface of the recipient (form) has a voice here as well as the conditions of the surrounding environment and recipient wall insulation ESPECIALLY if you desire uniform conditions of your mist in particular points/areas (see roots). Generate mist is easy… generate uniform mist is a bit different.


#8

@Webb.Peter, your drawing:

@Puxi, You may very well be right. I’m definitely not claiming this would be a reasonable means of growing food–perhaps it might, or maybe not. But, I do think it would be possible to experiment with cheaply in limited space.

For me, things like 16ft x 2ft root chambers, 100L accumulators full of high pressure liquid, clicking solenoid valves, etc. are not viable in the small indoor space I have to work with. Also, syringes are fairly cheap. If I had to replace a plastic syringe once or twice a week, that wouldn’t bother me at all. I realize that approach wouldn’t work well for someone who wanted to operate hundreds of machines, but I only want to operate one.


#9

For the dosing aspect, I’m testing these 3D printed peristaltic heads with brushed DC motors. I’ve squeezed aquarium tubing in. Stepper were too expensive so I’m using closed loop feedback instead. They need lots of torque, so will need to be paired with a worm drive or other reduction gearing.image

It ticks the boxes of cheap and easy to source


#10

@yusuf.khan.su what are you using peristaltic pumps for if your system is High-Pressure aeroponic (sorry, I’m just super curious!)

I’m very interested to hear more about this topic - We’re trying to compile information regarding the science behind aeroponics and it sounds like your experience may prove relevant. Please continue the conversation on this thread: Aeroponic design guideline roundup


#11

@Ya3ny can you share with use where you found stepper motor driven peristaltic pumps for $24-45 CAD. I use the same ones as the PFC 2 and find them to be accurate enough because I’m using a 25 gallon reservoir. However, when dosing 200 ml + across three nutrients parts it does take some time to dispense.


#12

The peristaltic pumps are for nutrient dosing into the reservoir. I’m trying to incorporate a filtration system that will allow the system to recycle the water, so it will need nutrient top ups.
I’ve realized that filtration is quite complex for a food computer, but the system will be useful for a food server.


#13

Using their app gets you 21% off this one:
DC 12v 24v peristaltic pump dosing pump 42 Stepper Motor Tubing Hose diaphragm pump vacuum Aquarium Lab Analytical Water
http://s.aliexpress.com/V7Nbe6jA
(from AliExpress Android)

This one costs less and is much smaller, but more difficult to change tubing:
Kamoer KPP-ST Peristaltic Pump 12V/24V Stepper Motor Pump (Pharmed BPT Tubing, Water Pump, Digital Control, Low Flow Rate)
http://s.aliexpress.com/qeeemMJb
(from AliExpress Android)

I’ll upload a photo of the two side by side when I get the chance


#14

@adam Hey! I’d love to see your system (sorry if you’ve posted and I missed it). I’m also super curious what software you run - it sounds like you’ve already got your nutrient dosing figured out. Have you seen this? Sourcing nutrients: Process automation

@yusuf.khan.su So you dose into reservoir and then run into HPA system? That has been my plan, but I’ve never really figured out a way to do nutrient top ups without throwing off the PH/Salinity longterm. What filter are you looking at? RO is most common from what I’ve seen but UV may be justifiable for the food server. I’ve never found anything near cheap enough for PFC.


#15

Yes. It works with the HPA as you described. I’m tried an activated carbon filter with a CFL UVC lamp. I haven’t done enough water tests to verify the efficiency of the process. pH balancing isn’t too difficult but without advanced water analysis in the system, nutrient levels would get thrown off.
The lamp was under 10USD and filters are common, so the problem isn’t the price but the complexity.

I also may have misunderstood what the topic is about.

@wsnook I think solenoid pumps are what you’re looking for. They are used in espresso machines and steam irons for very high pressures (7-20 bars). They can be found for 7USD apiece but lifetime is limited. Even with solenoids and accumulators, the diaphragm pump option is cheaper, scales better and is more reliable.
I don’t think high root chamber sizes can be avoided with aeroponics, but it does work well with hydro. You can also get 2l accumulators for a small setup.


#16

@yusuf.khan.su, For whatever it’s worth, I have kind of a niche set of goals and constraints that may be a bit outside the norm.

I feel like my potential contribution is mostly in the area of software, control algorithms, and maybe documentation–I’m not aiming to grow a lot of stuff myself. Also, any system I build needs to co-exist with me in a fairly small space where I spend a lot of time thinking and working. Minimizing noise and the potential for leaks are higher priorities for me than long term reliability or efficiency for growing a lot of food. I enjoy watching and tending plants on a small scale, so trading a level of maintenance and manual intervention for cost savings works well for me.

For me, quiet needs to be actually quiet–like a library–and I have a low risk tolerance for spraying even small amounts of high pressure liquid on nearby books, walls, carpet, electronics, etc.

Said another way, I’m interested in the aeroponic equivalent of a potted houseplant that wouldn’t feel out of place sitting next to a comfortable chair where people spend time reading. For me, being near plants and bright light during the day–without getting eaten alive by mosquitos–is very enjoyable. I’m curious if I can have that in a way that allows me to grow a little salad and make relevant contributions to projects aimed at larger agricultural production.


#17

@Webb.Peter, as a further extension to this idea, I’ve been looking at Lego Technic blocks, gearing, and linear actuators as a possible way of prototyping automatic syringe pulling and pushing. Here’s an interesting review of Lego linear actuators, http://www.technicbricks.com/2008/07/tbs-techreview-02-technic-pf-linear.html. And here’s a page with an example of linking a geared linear actuator with and pneumatic actuators, http://www.legoism.info/2011/03/pratical-power-transfer-linear-actuator.html.

[edit: another Lego linear actuator page: http://lego-technique.blogspot.com/2016/08/pneumatic-system.html, and a tangential possibly unrelated but really cool instructable on making a vacuum powered microfluidic pump: http://lego-technique.blogspot.com. The interesting thing about the microfluidic pump to me is that it looks like a possible low-cost DIY way of getting small controlled doses of high pressure fluid.]

[edit # 2: I also found a variety of syringe and blunt tip needle kits on amazon that are intended for things like dispensing glue and filling pens with ink. Blunt tip needles come in various wire gauge sizes as small as 30 gauge. So, by experimenting with pressure (syringe size and plunger force) and nozzle size (wire gauge of blunt tip needle), maybe we could find a combination that makes an awesome mist. Here’s an example of the industrial syringe & tip kits I found on amazon: https://www.amazon.com/dp/B074TVDVXZ]

[edit # 3: …and check out these re-fillable spray pump bottles with an attached swivel nozzle: https://www.amazon.com/Throat-Swivel-Sprayer-Colloidal-Essential/dp/B00SOT34U2. If you rigged something like that up to a larger tank and a lever actuator to push the pump, you might be able to just poke the tip through a slot in your root chamber. Besides nasal sprayers, there are also a bunch of perfume atomizers like this: https://www.amazon.com/dp/B00DT03YHO]


#18

Can we somehow include this/information regarding DIY HPA systems that aren’t “legit” but offer some insight into the “magic” and allow for one to get their feet wet. For example the DIY accumulators, or this syringe pump concept, I’d love to see it happen, but also agree it isn’t long-term scalable.

I specifically like the lego links, I think the long-term best solution is Air Atomised Aeroponics. I just did an energy audit at my day-job’s manufacturing facility and we found 150k in annual savings in air leaks. Hundreds of leaking pipes of compressed air all throughout facility, apparently this is common and 1/4 of all air is lost through leaks in manufacturing facilities in U.S. I only tangent about this because - NO ONE SEEMS TO CARE - why? Because it isn’t spraying water everywhere, it’s just air. Much easier to move/compress on a large scale than water. I say keep the nutrient/water local, and compress air all throughout a “food datacenter” in the long-term. I want to always keep our DIY/MVP projects pointed in the right direction - even if simplistic.

Bottom line: a lego pneumatic air atomised aeroponic system would be a sweet project.


Aeroponic design guideline roundup
#19

I added a “speculative designs” section to the aeroponic roundup post with bullets for “lego style” and “shop air style”.

[edit: Also, I’ll put more thought into the possibility of experimenting with a small system using Lego and syringe parts. I’ve been wanting a new short term project. Perhaps this would be something I could start on right away–it seems like the MVP github & documentation stuff we’ve been talking about may not be ready for action until later.]

[edit # 2: hmm… seems like the parts to get started playing with a Lego syringe pump thing could easily get up to the $100-$200 range by the time you figure in all the various parts for motor control and such. Looks like it would cost more than I can justify spending at the moment.]