Introduction: Will It Centrifuge? (part 3 - the Club Edition.)

It had to happen.

My science clubbers got wind of the centrifuge's existence, and demanded to have a go with their own samples. Some of them made their own mixtures, just to see if they could be separated by sheer force of gravity.

The samples got spun up in batches of four:

Batch 1:
  • Hair gel mixed with pure blackcurrant juice (yellow tube)
  • Mud, water, pencil shavings and washing up liquid (blue tube)
  • Brown sauce (it's a British condiment) (orange tube)
  • Salad cream (light pink tube)

Batch 2:
  • Flour mixed with green food colouring, washing up liquid, water and rice mixed with blue food colouring. (green tube)
  • Strawberry jam (with bits) (dark pink tube)
  • Flour, water and green food colouring (orange tube)
  • Raspberry jam (no bits) (light pink tube)

Batch 3:
  • "American hot dog mustard" (yellow tube)
  • Melted Margarine (blue tube) (melted by floating tube in hot water for a couple of minutes)
  • Crunchy peanut butter (orange tube)
  • Rice, water and blue food colouring (green tube)

I've posted each sample as "before" and "after", to make the changes (where they occur) more obvious.

The shot of the inside of the centrifuge shows a thin beige line - the clubber who filled the peanut butter tube didn't clean the outside of the tube properly, and slowing from 13,000rpm to stationary in a few centimetres mashed the debris evenly around the centrifuge's innards. Fortunately it wiped off easily.

Watch out for the margarine...

Need some backgound?
Part One
Part Two - Blood!
Original Forum Thread

And a "How To" Instructable is in the pipeline, I'm just waiting for some information.

Comments

author
PortalForce (author)2009-05-25

Wow! This machine is cool! I really love the experiments you are doing! I was just wondering where can you get it? And how much will it cost in Canadian money? I wonder what happens if you put Non-Newtonian Fluid (Oobleck) in the microfuge? I want you to try it, you don't have to, but I wish you did. Thanks,

author
Kiteman (author)PortalForce2009-05-30

I got it for free, donated to the school through a government scheme, but you could try here.

author
nfitz (author)2009-01-27

As you showed in p1 you're trying to run a 13k rpm centrifuge with a 12w (12v 1A) power supply. I bet its doing < 2 krpm. Give it more AMPS.

author
Kiteman (author)nfitz2009-01-27

It's the power supply recommended by the manufacturer.

author
nfitz (author)Kiteman2009-01-27

ok , just a suggestion. No harm will come of trying a bigger psu at the same voltage. Good writeup.

author
Sunny124613 (author)2008-08-27

ew i wouldn't try urine... but maybe is you try fatty yogurt or maybe some mayonaise

author
darth2o (author)2008-05-17

Urine, try urine!

author

urine for 1 hour at top speed would be interesting.

author
struckbyanarrow (author)2008-07-31

try soda please! 4.5 stars!

author
whatsisface (author)2008-07-16

You have to do a tiny martini in this. That's an order.

author
Sunny124613 (author)2008-07-08

I have never seen an instructable like this before! Anyways it is GREAT!!!

author
Kiteman (author)Sunny1246132008-07-09

Thank you, I try my best.

author
Clayton H. (author)2008-05-16

How much would one of them fancy "centrifuges" cost and were can I receive one?

author
Kiteman (author)Clayton H.2008-05-17

Most lab centrifuges cost upwards of 150GBP. The one I have is a "Millennium Product" - for some reason, the university-based team that came up with them sent lots to schools for free. They can also be purchased for around 80GBP+taxes - follow the links I gave in the text to find the details.

author
ItsTheHobbs (author)Kiteman2008-05-22

How about American dollars? I want to see if I have enough.

author
Kiteman (author)ItsTheHobbs2008-05-23

Probably about $150, plus various taxes and shipping from this link.

author
ItsTheHobbs (author)Kiteman2008-05-23

Oh, ok. not enough....

author
Zorink (author)Kiteman2008-05-17

My dad got one for me a few years ago from the hospital he works at. They got new ones and were just going to throw the old ones out! Testing random stuff in it can be surprisingly entertaining. Blood is the most interesting thing we ever put in it. My diabetic friend came over and he used his finger pricker thing to get some of his. After an hour the top 60-80% was a yellow/clear (plasma), the bottom was a deep red (blood cells), and the very tip was black/gray(platelets and other stuff).

author
jackfr0st (author)2008-05-18

these are wonderful macro pictures!...and what are the layers in the margerine? and what are the size of the centerfuge "capsules"?

author
Kiteman (author)jackfr0st2008-05-18

Actually, those photos were a pig to take - for some reason my camera refused to focus on the tubes. I think it's the lack of contrast. I had to put my finger beside them, focus on my finger and then move my finger. The layers will be fats and water (there's a lot of water in margarine). The tubes are 1.5ml - about 1/4 of a teaspoon full.

author
Goodhart (author)Kiteman2008-05-21

I wonder if using white or black paper, split in half with each half on one side of the tube, would have helped....or something like that.

author
Goodhart (author)2008-05-21

I just found out that some portion of the Chocolate making process involves a centrifuge. :-)

author
Goodhart (author)Goodhart2008-05-21

article in the newest MAKE: Timothy and the Chocolate factory....

author
Kiteman (author)Goodhart2008-05-21

Hah, just typical...

author
Goodhart (author)Kiteman2008-05-21

It is only mentioned in the article....I didn't give away what it is mostly about :-)

author
jlkinetics (author)2008-05-21

Maybe someone has mentioned it already, but how about Ferrofluid, or Magnaview Fluid? my bottle says magnets permanently suspended in oil. lets see if that really means "permanently". Also try brewed coffee.

author
Kiteman (author)jlkinetics2008-05-21

Hmmm, coffee would be appropriate.

author
GorillazMiko (author)2008-05-18

*sigh* I'm realizing a lot of other members are receiving "The Power" to feature.

Time to go look for part 2.

(+5/5 stars)

author
alexhalford (author)2008-05-18

How fast does a centrifuge spin? I ask because I have a vacuum cleaner motor that I have yet to find a decent use for...

author
Kiteman (author)alexhalford2008-05-18

This one goes up to 13,000rpm, depending on the input voltage.

Others are slower, others are faster, but the g-forces are a combination of the radius and the revs. Double the diameter of the device (at the same revs) and you will double the g-forces, but double the revs, and the forces go up four-fold.

author
alexhalford (author)Kiteman2008-05-18

And also, could I use a regular 555 astable oscillator with PWM to control the speed of an ac motor or would that only work with dc motors? So basically this circuit (see attached) with it's output going to the gate of a MOSFET. The MOSFET will then be the switch in the AC power cable. Would this work? Thanks for your help. AlexHalford

signal_generator_pwm.jpg
author
Kiteman (author)alexhalford2008-05-18

I think that circuit would behave quite differently - IC2 is specifically labelled with + and -, plus capacitors behave quite differently in an AC circuit.

And that circuit is only rated for 9V, not 120V or 240V.

author
alexhalford (author)Kiteman2008-05-18

Sorry I explained it poorly, I meant that this circuit would be powered by a 9v DC supply, and the output would go to a mosfet, which would be in the AC wire. This circuit would only provide the pulses to turn the mosfet on and off, only the mosfet would experience AC, the rest of the circuit would not. Like this (You'll forgive me I hope, the crudely drawn diagram):

signal_generator_pwm.jpg
author
Kiteman (author)alexhalford2008-05-18

I think you're best off asking somebody like Goodhart (or LasVegas if he's around).

author
alexhalford (author)Kiteman2008-05-18

Ok, thanks anyway.

author
alexhalford (author)Kiteman2008-05-18

Ok thanks, do you think a vacuum cleaner motor would do the job?

author
solo.card (author)2008-05-18

I'd have liked it if you used clear eppendorfs, some of 'em were a bit tricky to see through. I was surprised by the strawberry jam. I think you should definitely blast that one for a little longer. So through looking at your past instructables of yours, I have come to the conclusion that you are either a science teacher, or evil genius. I hope both.

author
bosherston (author)2008-05-18

Oh, I vaguely remember an O level physics lesson whereby a piece of cork and a paperclip were centrifuged - the cork sank and the paperclip rose? I don't remember the science behind it tho. Can you help Kiteman? Cheers.

author
killerjackalope (author)2008-05-16

yay I got to see my questions, the margarine was pretty nasty looking after, brown sauce seems alot more wholesome...

author
Kiteman (author)killerjackalope2008-05-17

I was surprised to see so little oil on top of the peanut butter. Maybe if I'd time to run it longer...

author
killerjackalope (author)Kiteman2008-05-17

if you leave it in the cupboard for a while it breaks up from the oil, it's quite thick though so maybe it just needs longer...

author
Tool Using Animal (author)2008-05-16

Curiosity got the better of me, now I know way too much about Brown Sauce

author

A classic of British cuisine!

author
Weissensteinburg (author)2008-05-16

Won't a centrifuge start to slide if the tubes opposite each other don't weigh the exact same?

author

I'm assuming thats why he only did batches of 4, so he could do 2 of each? Maybe not... How was the flour mixed? I'd like to see a kneeded mixture and possibly find gluten!

author
Kiteman (author)zachninme2008-05-17

The flour was just stirred with water - the kids made and brought it their own mixtures.

author
Kiteman (author)Weissensteinburg2008-05-17

I worked on the theory that the samples the kids brought in were all mainly water, or at least of similar density. I did four at a time, spread out around the tube, and it seemed to run very smoothly. As Patrik said, the rotor is significantly more massive than the tubes, probably deliberately.

author
Patrik (author)Weissensteinburg2008-05-16

The rotor itself is probably far heavier than the tubes. So as long as you make sure that opposite tubes are filled with approximately the same amount of material, you should be ok.

author
Patrik (author)2008-05-16

Hey Kiteman - how long did you centrifuge these? As you found out with the blood, you may need to centrifuge some of these longer to see results.

author
Kiteman (author)Patrik2008-05-17

They were all five minutes at 8500g - any longer and half the club would not have had a chance to try their samples.

It's surprising how long it takes a ten-year-old to scoop exactly 1.5ml of peanut butter into a tube.

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