Re: [DIYbio] What's wrong with open source PCRs


Built worlds most dangerous hot air PCR thermocycler w/ Hackteria a while back. Arduino, triac, thermocouple, misc electronics, and 8-euro hot air hair dryer.


https://www.youtube.com/watch?v=XOjkyP8_Mm8

It was hard to determine the temperature of the mastermix in the tube. We tried embedding a thermistor in a similar mass at the bottom of a tube, but it was really fiddly. It seemed that the devil was in the details of knowing what particular temperature the tubes were at.


It's interesting, I see maybe 5 different hair dryer pcr projects when searching google images for "hair dryer PCR"


One of them is from a 2015 iGEM team: http://2015.igem.org/Team:UMaryland/Hardware

Maybe we should have a contest: who can make the most unlikely / rube-goldbergy thermocycler work?

Keep on 'cyclin
Mac

On Wed, Jan 27, 2016 at 10:18 AM John Griessen <john@industromatic.com> wrote:
On 01/26/2016 09:09 PM, Jonathan Cline wrote:
> Historically there are thermocyclers designs which use fans and electronically controlled vents to direct heated (or room
> temperature) air for assisted ramping.

I think flowing air is the way to lower costs even though it has moving parts which will require engineering.  The moving parts
could be organic piezo material for doors, teeny fan motors with long shafts, and be low cost possibly.  Losing all metal blocks
will win out by air stirring.


>
> Here's an example typical use case (synbio purification-ligation) to contrast to your example.
>
>
> 100 cycles    12 °C   60 s
>
>       22 °C   60 s

>       12 °C   60 s
>
>       22 °C   60 s
> Hold  16 °C   infinite


Is this below office/lab ambient, (requiring refrigeration), a frequent desirable use case?


On 01/27/2016 11:06 AM, Sebastian S Cocioba wrote:
 > Think something like this will work? Hand wrapped springs soldered to copper heatsink and thermal-paste-bound to two Peltier.

Yes it will work, but not win the efficiency prize, or the speed of heat transfer prize either with the uneven coil surface.
Stirring the air between the peltiers would be better.  The peltiers's masses will slow the ramp when you reverse and go from cool
to heat pumping.

If you could find a tiny motor/propeller from a toy battery powered boat to put in between there it would help.  Trim the plastic
propeller to fit, and lose the coils of wire...

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