Oxford Nanopore's MinION Probably Costs About $200 To Make

Based purely on public information, let’s try and figure out what’s in an MinION DNA sequencer. Unlike my previous post, we’re only going to use public sources, not things ONT says we mustn’t buy on eBay.

Rather helpfully David Deamer’s book shows an exploded view of the MinION. I suspect Professor Dreamer is not in violation of his usage agreements with ONT, but if Oxford believe my quoting his book is tortuous interference as they stated before, I’m sure they’ll let me know:

So we can see that the MinION contains only two important digital logic components a “USB 3.0 chip” and an FPGA. It looks like there’s something on the back of the PCB, but we can’t see what it is. There will obviously be various regulators and other components to support the digital logic and ASIC.

If we “bing” for USB 3 controller the top hit is the FX3, for 5 gbps USB 3 controller, it’s basically the first page:

The FX2 is a pretty versatile and hacker friendly chip, but USB2. So the FX3 seems like a reasonable option. Are there any other good options for 5 gbps USB 3 controllers? I couldn’t easily find one… The FX3 costs about $20 to $30 in volume:

On the FPGA side, Xilinx is the most popular manufacturer of FPGAs. In recent years it seems like Xilinx are basically the only game in town, I rarely see anything else…

Looking at Xilinx’s list of devices on wikipedia, it looks like we’d be looking at the Spartan 6 as the 7 wasn’t out in 2015. The Vertex would be too big and dissipate too much heat I think? Could possibly be a Zync?

Let’s try and draw an equivalency to existing designs and puzzle things out. Dreamer’s book says the MinION can acquire data at up to 33KHz per channel on 512 channels. With 16bit samples that’s 33.7MBytes/s.

The Axiom camera is 4K and can capture at 300fps. About 13GByte/s if my math is right? A few orders of magnitude higher than required. That uses a Zync 7020. Out of stock on Digikey, but has a list price of about $200.

In my lab I have a Analog Discovery 2 this uses a XC6SLX16-1L. It has a baseline sample rate of 100MS/s at 14bit. Let’s just call that 100MBytes/s. This would be 3 times the bandwidth required for a MinION. While some work might be required to get this performance on continuous acquisition, it seems like a tractable problem. Also out of stock, but the Digikey list price is in the $50 to $100 range. The equivalent Spartan 7 part (XC7S15?) is about $30. The model up (XC7S25) is in stock at ~$50.

So, let’s go with $30 for the USB3 interface, $50 for the FPGA, another $30 for misc logic and regulators? Giving us an estimate of $110.

Then we need to add on the cost of the milled enclosure, this could actually be the most expensive part of the unit when ordered in small volumes. But even so, I’ve had small milled aluminum enclosures made in single units for ~$20. I would round it up to $200 for all the various small parts required.