Decision time!

So, I have done quite a bit more research into the design of my PCR machine. I can follow one of two options:

1) Make the cheapest possible PCR device. I estimate that this will cost under $1, but will be limited to replicating DNA fragments of up to about 200 base pairs. That might be enough for DNA fingerprinting, and really small genes, but its pretty limited. It will however be easy to make at home and in schools.

2) Make a useful PCR machine with a fixed extension time of about 30-60 seconds, enough for amplifying up to 2-3 thousand base pairs with a fast polymerase. This will need much more electronics, and probably end up costing around $30. It will be a project suitable for intermediate makers, but probably beyond that of most high school kids.

I'd love to hear some input at this stage, before I choose a direction to go with.

Discussions

Chris wrote 07/15/2014 at 07:45

I was part of a project to make handheld PCR machines for real-time diagnostics during an office visit to your doctor. In my experience, controlling the accuracy and speed of the temperature changes is pretty critical. I think that PID control is almost required, and the shape and size of the reaction vessel is important. Temperature differentials within the solution volume caused many of our attempts to fail.

I don't want to dissuade you from taking a whole new approach that capitalizes on convection cycles. That sounds pretty cool and clever. But I'm worried that a $1 system that is overly finicky and has a low success rate isn't going to be perceived as reliably useful. If you can get it reliable, that would be truly outstanding.

But at the end of the day, a $30 PCR machine still seems like a HUGE leap forward. The cost of reactants and the subsequent tools to detect the amplified DNA are going to require a few dollars. So $30 for the PCR part would seem very affordable.

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Kenji Larsen wrote 07/14/2014 at 13:06

$30 is still amazing for a machine of this nature. It probably won't be that much of a hardship for students if they are at this level of technology, and their parents understand. Are you able to architect it so that the $1 version is a modularized subset of the $30 one? Even if that makes it $2 for interfacing, maybe that is a way to go.

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davedarko wrote 07/14/2014 at 09:11

Where is the harm in doing both?

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Modelling update

Discussions

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