PocketPCR

I once hooked a high current 10Hz AC signal to a peltier plate. It made ice 'flicker' on the plate as it melted and froze 10x per second.

It was really cool to rub your fingers over it - it made a kind of haptic feedback device as your fingers froze and unfroze from the plate.

It did require kilowatts of cooling on the backside of said peltier plate...

Ha! Finally my day job.

If you're using off the shelf plastics as your reaction vessel (which most of these do), then you're immediately stuck with these large thermal mass systems.

A few reasons why many of these machines stay away from microfluidics:

PCR reactions are notoriously susceptible to cross-contamination, so microfluidics wells would either need to be thoroughly cleaned (a pain), or just single use (this is what we do with most plastics... - which would be expensive).

How do you get your stuff into the well! Current scale plastics had amendable to human operators (infinitely flexible, minimal capital cost, easy to replace). The equipment you need (basically a good pipette and tips) is relatively cheap and well understood. To do this at the microfluidics scale would be much more expensive (and see the same cleaning concern from above).

What are you doing with your PCR result? Assuming that you're just going with florescent probes, having the giant macro-scale lump of liquid gives you both a physically very large target, and a relatively brighter target to look for. This can certainly be overcome, but is more engineering work.

If you were using PCR as an upstream process (dunno how common this is now anymore), then you need to generate enough volume to be useful in your downstream process... and if your downstream process is human scale, then you're PCR reaction needs to be as well.

Oh, and finally the actual PCR bio-chemical reactions take a finite amount of time to work, so you can't really temperature cycle by the kilohertz. Probably the fastest you can take it is... dunno, 10 seconds per cycle? The literature is a little weird here.

Cycling will be rate limited by the speed of the polymerase involved in the reaction. Short sequences are usually fairly quick regardless, but the extension period is still measured in seconds per kilobase.

Also, some primers really do not cooperate at fast cycle speeds. PCR is really quirky even in optimized conditions.

In my experience it’s easier to measure and thus control the temperature of a thermal mass that is much much larger than both the sensors (thermocouples) attached to it and the samples inside of it.

The large thermal mass of the heating block in a traditional thermocycler vs the relatively tiny masses of the samples inside the pcr tubes contained within means that the samples are basically always at the temperature of the block, which means the control loop for the heating/cooling system can be modeled and controlled with just a PID feedback loop.

At first, I didn’t realize the the disk on the left was being used to hold down tubes in the thermal block. I thought you might load the tubes into it and then it would turn to put tubes in smaller blocks that were at different temperatures. If it did this, then that would be the ultimate throwback to when we would actually move tubes between water baths/heat blocks to manually “cycle” the tubes.

PCR is literally the lowest hanging fruit. It is a glorified rice cooker. There are many bigger open hardware problems to tackle in biology such as sequencing, anything optics related, and general process automation. It is not good for hardware and software people entering the field to get distracted with making PCR machines.

To put it in context, take for example web collaborative software. They are very hard to build correctly and get right so most collaborative software in general are close sourced SaaSes. Imagine if a bunch of native/desktop software engineers decided to take a look at the problem and suggest that, hey, we need more open source real time collaborative software so let's build yet another web framework. Another web framework isn't needed and doesn't solve the problem! The problem is lack of correct CRDT and operational transform libraries. We don't need yet another web framework. I hope this analogy makes sense because everytime a biology thread comes up on HN the discussion pivots to "how can I help by focusing on x y z bioinformatics etc" and completely misses the point. Hard problems sometimes need to be tackled head on.

Leave low hanging fruits to academia and interns. If you are a software/hardware engineer with >5 years of experience then recreating the Todo MVC equivalent in biomedical engineering isn't helping anyone. Many of the bio posts here feels like those low effort and inaccurate web dev tutorials on medium.com written by bootcamp grads that would never make it to the front of HN, but for some reason the people here are happy to swallow the equivalent in life science hook, line, and sinker.

PCR (Polymerase Chain Reaction) is the standard procedure for duplicating DNA, which is a critical step to many different protocols, including COVID tests (real-time PCR) and DNA sequencing. This device is a miniaturized thermo cycler, which heats up and cools down a sample in a small test tube according to a pre-programmed sequence. Heating/cooling cycles are necessary for the enzymes involved in PCR to do their jobs.

The FAQ seems to answer that you can't use it for COVID tests. Are there resources out there for beginner friendly experiments you can do with this kit?

Sorry but the idea of abstracting bio hacking for the unwashed masses seems like a horrible idea. Sequencing and info extraction sure, but you don’t want Joe Dirt having an automated way to synthesize anything that can augment biological processes.

Their midi theremin is awesome!

No, that requires a PCR machine with an optical fluorescence sensor, which is much more expensive.

It’s just a basic thermal cycler, not a real-time one with fluorescence detectors. You would need something like a gel electrophoresis system and a transilluminator to check the results.

This is a good remark. Covid19 is detected using so called q(quantitative)PCR or Real-Time PCR. This indeed requires real time fluorescence detection as the thermal cycle at which your signal starts to ramp up is a measure for the amount of DNA or RNA molecules present in the original sample.