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Lab Equipments Answered

Look at the video attached. Those of you working in biology/chemistry  research labs may be familiar with these. One of them is a rotator (with small tubes fixed in the clips) and the other one is an orbital shaker (well, technically they're both sold as rotators).

Can anyone please help me with building either or both of these. I have never done a DIY project before and would love to start with these.

It doesn't have to be exact same design. It could be something very simple but functionally similar. It should be able to run for extended periods without overheating (24-48 hours). Also, I would prefer something that can run in a cold room (4 degree Celsius) but I can use anything right now.


Much thanks in advance!


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6 years ago

That video still does not work for me, but that's ok. I think i have an idea of what you're looking for.

Mechanical agitators to increase growth rates of a culture....
That's actually easier then a centrifuge in allot of ways.

The first thing you need to look at is the tube it's self.

I'd get a rubber stopper or cork that fits the opening and drill out a small hole in the center of the cork/stopper.
I'd then feed the rotor of a small brushed DC motor in the 1.5-6 volt range (it's actually a big range) through the rubber stopper and attach a stirring paddle/bead.

As far as specifications on the motor goes, voltage isn't going to be a huge deal because you want low RPMs (like 1-2 rpm), and voltage tends (as a very generalized rule) to go hand in hand with high RPM. The thing you need to watch out for is amperage because amperage tends to relate to the torque in an electric motor, but also the heat capacity of the motor. In General, an electric motor built for high amperage can dissipate heat more efficiently.

The paddle can be as simple as a bead glued to one side of the rotor, though you need to be aware of the sensitivities of the antibodies to the adhesive. Soldering a glass bead is a possibility. If adhesive is a non-issue, you could just use tape.

As for variable power control, an adjustable resistor is cheap, and can be found in a range of tolerances.
The biggest deal with power is matching the motor specifications, but since you're just matching voltage, conforming to size constraints, and looking to maximize amperage, that's not hard.

You'll probably want to solder it all together eventually, but if you want something more modular, you could just clip it together with alligator clips.

The shaker is a little harder.

I still can't see the video, so i'm not entirely sure how vigorously you're running things, and such details tend to be relative. That said, you mentioned that you have magnetic beads....
They sell the coin vibrator motors from cellphones. You could press that together with some aluminum foil, some small watch batteries or capacitors, pack it into a plastic tube and seal it with hot glue to keep it all contained.

The vibrator should interact with the magnetic beads, propagating the vibration through the fluid, but you might need more then one vibrator to get the proper amount of agitation. Also... you might want to make sure the interaction with the magnetic beads is relatively gentle. If it shoots a bead off like a bullet, probably don't want to use it, but the size and power of a cellphone vibrating device shouldn't impart that sorta energy.

Adding extra magnetic beads would alter how the vibrator motor propagated the agitation through the fluid, but not necessarily the intensity of that agitation. You might have to do some experimenting to get this right, but, they do have very small vibrational motors that would work great for this. Most are very reasonably priced (less then $10.00 US).
This would greatly enhance the portability of a shaker, and, if you needed, you might be able to get it to act as a weak Homogenizer by increasing the voltage you're pushing through it, but I'd need to familiarize myself with vibrator motors better before i could give you a definitive answer here.


6 years ago

Hi Qcks! Thanks for replying.

I think they sell it as 'rotators' because it's used more to shake a sample during incubation. I'm wondering if you were able to see the video on youtube; I realized that I left the video as private but if you try again, you'll notice that the speed of both equipment is fairly slow (40-60 RPM/minute suffices).


As far as load bearing ability is concerned, the weight of samples is minimal. The tube rotator will barely have 10-50 gms of load and the orbital shaker (the one with plastic boxes on top) may go up to a lb. Let me know if you need any more details.

I just realized that it will be awesome if this could run with a rechargeable battery!!


Reply 6 years ago

I forgot to add, the tube rotators have small clips attached and each clip holds a 1.5-2.0 ml tube or a 15 ml tube (which I rarely have to use). These tubes have liquid samples being incubated with antibodies or magnetic beads and the protocol requires that the samples are constantly being turned (like you would gently invert a vial multiple times to mix it's contents).

The orbital shaker on the other hand shakes small plastic boxes. We put paper thin membranes or a gel which needs to be constantly wet with few ML of buffer or antibody.

The orbital shaker in the video has a dial which controls speed but honestly, we never use it over the speed shown in the video.

Again, let me know if you need any other details.


6 years ago

A centrifuge?
If this is what you want, it's not normally called a rotator.

Considering how i'm working on one right now as part of a home biochem youtube series, I can tell you quite a bit about making one. What sort of volumes are you talking? How much force do you want to subject the different mixtures to? There's a plan for a small volume Centrifuge that attaches to a drill that can be printed on a 3d printer. Honestly, it's the best thing for 2-20 ml volumes that I'm aware of, but if you plan on doing anything bigger it gets a bit more in-depth.

As for the Shaker, That one's both harder and easier at the same time. It depends on how fast you need it to shake. I assume you're trying to culture a micro-organism of some sort; you should have an idea of what you're trying to culture, because different things require different rates of agitation, which dictates how rugged and how expensive a shaker will be.
Again, if you're talking low volumes with a small amount of agitation, you can accomplish that with a simple stirring rod attached to a motor that just sorta sits on top of the flask.

So... hope this helped. It sounds like you're doing something interesting at the very least.