When the first thermal cyclers for the polymerase chain reaction came out in the 1980s, they were as expensive as a market driven by grant money could make them. Things haven’t got much better over the years, largely shutting STEM classes and biohackers out of the PCR market. That may be about to change, though, if the €99.00 PocketPCR thermal cycler takes hold.
PCR amplifies DNA in a three-step process: denaturation, which melts double-stranded DNA into single strands; annealing, which lets small pieces of primer DNA bind to either side of the region of interest; and elongation, where the enzyme DNA polymerase zips along the single strands starting at the primer to replicate the DNA. The cycle repeats and copies of the original DNA accumulate exponentially. Like any thermal cycler, [Urs Gaudenz]’s PocketPCR automates those temperature shifts, using a combination of PCB-mounted heating elements and a cooling fan. The coils rapidly heat a reaction block up to the 99°C denaturation temperature, the fan brings that down to the 68°C needed for annealing, and then the temperature ramps back up to 72°C for elongation with thermostable DNA polymerase. PID loops keep the reaction temperature precisely controlled. The whole thing is, as the name suggests, small enough to fit in a pocket, and can either be purchased in kit form or scratch-built from the build files on GitHub.
We applaud [Urs]’ efforts to get the power of PCR into the hands of citizen scientists. Quick and dirty thermal cyclers are one thing, but Pocket PCR has a great fit and finish that makes it more accessible.
Thanks to [Abe Tusk] for the tip.
23 thoughts on “Put The Power Of PCR In Your Pocket With This Open-Source Thermal Cycler”
So, umm, what does PCR do for us?
I think making many copies of the DNA is the first step in some DNA visualization process.
Microbiology! Are you eating the wrong kind of e.coli? PCR can tell you! Try wikipedia before knocking the hard sciences!
Most microbiology is kinda squishy
Step 1: Cut genes out of a larger stretch of DNA (like a genome) with restriction enzymes or something.
Step 2: Isolate the DNA you want by size using gel electrophoresis.
Step 3: Use PCR to make lots of copies of the gene or DNA that you are interested in.
Step 4: Use your DNA for research or development. Maybe you want to play with CRISPR or stick a gene into a plasmid or viral vector or something, and now you have enough of the DNA to do that.
The only problem is that you still need ‘primers’ for the PCR process to work, and those are bespoke stretches of a few dozen base pairs which you still need to order from large companies who aren’t usually thrilled to work with tiny-volume individuals. The perishable materials also add up, and you’ll want other equipment like -20C and -80C freezers. Biology is hard.
It allows you to replicate your enemies DNA (If you can get a sample) and then use a spray bottle of it to coat a crime scene with it.
Is that really likely to work though? I was under the impression that loose DNA strands were rather fragile in the environment if not in a favorable medium or embedded in something, like a skin flake or hair root etc.
It allows you to make millions of copies of targeted DNA which can be ran through gel electrophoresis and confirm whether or not that gene of interest is present.
Great project! A few years ago I was stuck using an unreliable thermal cycler because repairing/replacing it was too expensive. I’m sure that many have had this experience; lower-cost thermal cyclers are an important contribution to science.
I hate to say anything negative about such a good project, but I’m slightly concerned about the exposed circuitry. When I was in a biochem lab, we’d occasionally need to wipe down a lot of the surfaces, ex. if something really nasty spilled. It would be difficult to wipe this machine. And an unlucky spill could probably short out the machine.
OTOH, none of my builds enclose all the circuitry, so my comment is probably quite hypocritical. Regardless of this, I’m very impressed by the project.
Did OpenPCR not change everything?
Last I heard the limiting factor was the availability of the reagents.
The wells aren’t deep enough wth is going on with this thing?
Usual reaction volume is <= 50uL. Don't need to heat the whole thing.
I’m always amazed that anybody thinks science can be accomplished with closed source hardware. I mean, a broken clock is right twice a day, and I’m sure a lot of science is accurate, but without being able to know how your instruments work, there is an unavoidable degree of uncertainty.
Even more low cost with a jar of hot and one with cold water and two stepper motors:
I’m not doing PCR myself but the results, shown with the electrophoresis look good enough for the citizen scientists. Has anyone tried this?
I’d like to test it ;-) Idem for the thermocyler made by BioHackAcademy https://github.com/BioHackAcademy
I am disappointed. This looks nothing at all like the most common consumer thermocycler, the E-Z Bake Oven. Frankly, a thermostat set up to control the bulb (or heating element in more modern designs) would be pretty awesome, honestly.
why does everyone always take a huge shortcut and assume thermocycler==pcr seriously that pisses me off. open source effort are just to make home lab equipment cheaper but a thermocycler is hardly the largest hurdle for biohackers that want to play with DNA.
What would be the larger hurdles ? Apart from time learning etc …
short answer: the biggest hurdle would be getting all the supply and set up a lab where you can work with DNA/RNA.
long answer: most company that sell chemical supplies usually don’t sell small quantities so unless you need a few 100 gram to kilos at once your out of luck. also the vast majority of those companies don’t sell to individuals, only to company so unless you own your own company good luck getting supplies. this is especially true for biotech/lifescience stuff like enzymes, oligonucleotides and primers. the only way to get those things in small quantities and easily is to use biohacker friendly company like the ODIN. the problem there is that you can usually only buy kits that do only one thing so not really useful for actual citizen scientists.
if by any miracle you managed to gather all you need you still need to setup a lab that is very clean an keep it that way. think of PCR product as “concentrated” DNA even minor spills or cross contamination can potentially be catastrophic ( to you experiment at least not to you health if you do it right). not to mention the nagging little problem of RNase and DNase that are almost ubiquitous everywhere.
It doesn’t look so bad. Obtaining primers is very complicated. Slow delivery and laws in additional.
Looking a way to sequence dna to digital.
Did you trying nanopores?
It looks excellent and doesn’t require primers. The cons here is non reusable cell. It would be great to find a way to reuse cells.
Cute, but mineral oil needed. There is a $500 “openpcr” machine that does 16 tubes and does not need oil. I agree that a heater would prob require more power than USB. Insulate tubes with styrofoam?
Hi all, I have a client who is looking to develop something like this pocketPCR and it seems to me that perhaps this could be something this project needs, a new kick start to keep it progressing. it is getting away from the private person who wants to do PCR at home for whatever reason. This client is looking to sell this product with a very specific TB test kit that they have developed for developing countries. is this something that this project would be interested in?
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