Recently, Young et al. Nano Lett 2024 described the use of Vittorio Saggiomo’s 3d-printed+ Ender Flow pumps to make organic nanoparticles (liposome, polymer nanoparticle, and solid lipid nanoparticle). But how do you characterize them? Let’s build a DIY dynamical light scattering device…

Comments on Young et al. setup

  • Experimental setup uses Vittorrio’s pumps. We’ve built some already.
  • Mixing is just done using T-junctions
  • Experiments they describe look like just mixing two components?
  • They make a batch and then characterize it. They are not doing this in a closed loop. DLS is a possibility, some of the nucleic-acid containing nanoparticles also support fluorescence (but after a centrifugation step)

Dynamical Light Scattering Theory

Existing DIY DLS projects

  • OpenDLS comprehesnive build guide, using a Thor Lab 650nm 4.5mW laser module (CPS650F), Vishay BPW24R photodiode, and TI TLC082IP opamp, all driver off an Arduino. Nice 3d-printed case. Cuvette based. Reading between the lines, you need to acquire ~5 minutes of sample to get a decent fit. Looks like the available ADC samples at 67 kHz, which gets fed into a buffer.
    • Comment thread suggests you might just use USB oscilloscope and call it a day (save the output to disk for analysis)…then you don’t need the arduino at all…and no amplifier or ADC either

The Need For Speed

  • Ekkens Physics Teacher 2024 describes how to use a Pico to modulate a 5 MHz laser square wave and how to use a Hamamatsu S5793 ($20) and high-speed amplifier Analog Devices AD848JN ($5) to detect it
  • In principle, you can set the integration time on the MAX44009 to 6.25 ms = 160 Hz samples, but that aint enough (and it is one of the faster commercial kits out there)