How do you spin things fast in the backcountry?

Most DNA extraction methods require spinning samples in tubes very fast. In a normal biology lab with power and benches we'd use a centrifuge, but if you've ever picked up a centrifuge (I haven't) you'd know those things weigh like 40 pounds! Since mid-January, we've been thinking about how we are going to spin things fast in the literal middle-of-nowhere. This paper was the document that convinced us that off-grid solar-powered sequencing was both possible and could yield publishable results. We looked back at the paper to see how they spun things. We found that their team had 3D printed this adapter so that they could use a dremel to spin microcentrifuge tubes. As my friends who are mechanical engineers explained, a dremel is a dheld tool that spins really fast. Like, 5,000 to 35,000 rotations per minute. A dremel weighs about a pound with the battery in it, which is convenient since we have to carry it deep into the woods. And 3D-printing is easy and fast. Had we solved it?

No! There was a catch! The solar-powered field sequencing paper describes the dremel as a "hand-held" solution. It also describes how the the plastic adapter broke while the dremel was spinning. Which is terrifying, because when you are on your knees sequencing in your tent-based field lab, the literal last thing you'd want is the unpredictable release of high-velocity plastic shrapnel at eye level. Or at any level, really.

So, we set out to engineer our own "dremelfuge" --- our version will include a stand for the dremel and an attachment to allow the dremel to spin tubes--- with the following design constraints:

(1) does not spin things at eye level

(2) does not tear itself apart while spinning slightly unbalanced loads

(3) can be weighed down with environmental objects, like rocks or sand

(4) can be disassembled (ideally without tools) and packed relatively flat

 

A traditional screenshot of the initial stand design, in progress.

The final version of this model was too big to fit in the build volume of the printer. So we made it shorter, and adjusted some of the angles. Since it's so big, our dremel stand is taking 34 hours to 3D print!