Last week, the university conducted a vibration study by dropping 5000lb (2268kg) weights from 15ft (4.6m) in four locations near the CAT Facility Lab. In biology terms, that’s like dropping a rhinoceros from the height of a giraffe. Why? No idea. But when life presents an opportunity like this, you collect data and don’t ask questions. Since flow cytometer performance is dependent on precise laser alignment and constant pressure, we were curious if we’d notice any “shockwave” effects in our data acquisition. Would certain laser wavelengths be more sensitive to vibration than others? Would we see the characteristic “judder” of acquired events when the pressure is unstable? Would the streams on any of our Aria cell sorters be disturbed? Can flow cytometers get PTSD?

Here’s a short video of one of the drops nearest our lab for context. It’s not as cool as you think.

To test this, we ran eight peak rainbow calibration beads on our Fortessa 4-15 for the duration of two sets of drops (four drops 10am-11am, then four drops 11am-12pm). Qualitatively, the vibrations were, at most, slightly noticeable to any humans in the lab even when drops were done very closeby. The Fortessa’s acquisition was also unaffected, and even the sensitive (sometimes fussy) stream formation on the sorters showed no perturbation.

a)b)

Figure 1. Eight Peak bead acquisition during weight drops. One channel for each laser is shown for demonstration. Beads were acquired continuously over an hour for the a) 10am-11am drops and the b) 11am-12pm drops.

The CAT Facility is below ground, so it could be that some of the vibrational energy was diverted through the walls – if it traveled directly up from the floor, I’d expect a more noticeable tremor. Good to know if we ever need the lab to double as a bomb shelter. Additionally, it was raining that day which softened the soil of the drop zone a bit. This might have let the weight penetrate farther, thus reducing the impact force. Even without these factors, however, I doubt the effect would be much stronger. In conclusion, while it would have been interesting to see the vibrations affect the cytometer, it is comforting to know how well our instruments’ shock absorption works.

Next time we’ll drop an elephant instead.