MagOD

Magnetic Optical Density meter Tijmen Hageman, Jordi Hendrix, Hans Keizer, Marcel Welleweerd, Dave van As, Ruthvik Bandaru, Rob Krawinkel, Leon Abelmann.

KIST Europe, University of Twente

Other sources

Next to software, also the source codes to create hardware are available here, as well as :

• Measurement head design, 3D print file (OpenSCAD, on Thingiverse )
• Spice simulations, electronic diagrams, PCB layout (Spice, KiCad on Dropbox)
• Laser cut pattern for housing electronics (DXF, on Dropbox)

Specifications

• Up to 800 samples per second, allows precise analysis of the rotation speed of magnetic bacteria
• Three-dimensional quasi-Helmholtz configuration, with fields up to 5 mT
• Three color LED: red: 645 nm, 1000 mcd, green: 520 nm, 1700 mcd and blue 460 nm, 500 mcd
• Power supply with current feedback to compensate for coil heating, cut-off frequency 200 Hz
• Large area photodiode (sensitivity 0.5 mlx, with green LED theoretical max OD range of 5.8)
• Integrated pre-amplifier, SNR 83 dB (max OD range 4.0).
• Dedicated 16-bit ADS1115 DA converter
• Integrated temperature sensor
• Reference light detector
• Scattered light detector
• Fully programmable (ESP32 using Arduino IDE), open source
• User friendly spreadsheet recipe definition (csv format), with software to validate correctness
• Data collection on SD card, accessible by ftp over Wifi

Additional info

• Marcel Welleweerd and colleagues (2022) "An open-source automated magnetic optical density meter for analysis of suspensions of magnetic cells and particles" Review of Scientific Instruments Vol 93, Issue 9, 094101. The manuscript can be found on ArXiv
• Chapter 8 in Thesis Tijmen Hageman.
• Presentation by Leon Abelmann at Intermag2021