May 13, 2016 at 03:00AM

Yesterday I Learned: 1) The Echo Liquid Handler is a ridiculous machine. It's sort of a pipetting robot... except that instead of moving liquids around by pulling them up with a pipette tip and dispensing them, it works by spitting tiny droplets of liquid through the air with ultrasound. The machine uses two plates -- a source plate and a destination plate. The source plate is placed in the machine, and has wells filled with whatever liquids you're interested in moving around. The destination plate goes in *upside down*. The Echo moves the destination plate around so that a destination well is over a source well, then pulses the source plate with ultrasound to send tiny (order of magnitude 1-50 *nano*liters), precisely measured droplets up into the destination plate. Obviously, this limits it to working with pretty small volumes, but it's really fast (a few minutes to fill a plate), flexible, absurdly precise (supposedly), and works great at low volumes. The Echo also has one of the funniest failure modes I've ever heard of from a lab robot. The Echo can't handle bubbles on the surface of the source plate wells. The problem is that if it sees a bubble, it will interpret the *bottom* of the bubble as the top of the source liquid, and the *top* of the bubble as the bottom of the destination liquid, and will very precisely spit drops from the source well to the top of the bubble. 2) Relatedly, most plastics that are acoustically transparent (that is, transparent to ultrasound) are also visibly clear. Who knew? 3) DMSO has a very high surface tension, but low viscosity.