The industrial designers who work on medical devices like COVID rapid tests have it tough. Essentially, they have to figure out how to transfer a patient's snot into a little machine in a foolproof way. To understand the challenges this poses, let's look at all of the steps required to accomplish this with the Accula PCR testing kit developed by Mesa Biotech Inc.

First you've got to swab the subject's nose, and right off the bat you can see the opportunity for error. In the Accula instructional images, they show the swab being used just inside the nostrils:

In contrast, this video from Johns Hopkins Medicine shows swabs for COVID testing must be inserted rather deeper:

Meanwhile this image from UC Davis Health illustrates a COVID-testing swab being inserted so deep, it looks more like they're testing for pain tolerance:

It's not clear if Accula's test requires less invasive swabbing than what Johns Hopkins or UC Davis recommends. In any case, the next step in the Accula process is to stir the swabbed sample into a solution in a tube.

Then you've got to unwrap this pipette:

The pipette is inserted into the solution, and you use it like an eyedropper to extract an unspecified portion of it, ensuring "there are no air bubbles in lower part of pipette," though it's not clear what to do if there are, or how to avoid them in the first place.

Next this single-use test cartridge is inserted into the dock.

Then the pipette is used to transfer the solution into a port on the top of the single-use cartridge.

Thirty minutes later, the dock has finished processing the cartridge. It's removed from the dock, and an indicator on the cartridge--not the device's screen, as you'd think--provides the results:

If the procedure seems confusing in a text description, here it is illustrated in video:

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The cartridge insertion step seems pretty foolproof, but it's the collecting and transferring of the sample that seems tricky to me. However, it appears that with current technology, this is about the best we can do. I don't envy medical device designers.