An open-source automated magnetic optical density meter for analysis of suspensions of magnetic cells and particles

Marcel K. Welleweerd, Tijmen Hageman, Marc Pichel, Dave Van As, Hans Keizer, Jordi Hendrix, Mina M. Micheal, Islam S.M. Khalil, Alveena Mir, Nuriye Korkmaz, Robbert Kräwinkel, Daniel M. Chevrier, Damien Faivre, Alfred Fernandez-Castane, Daniel Pfeiffer, Leon Abelmann*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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We present a spectrophotometer (optical density meter) combined with electromagnets dedicated to the analysis of suspensions of magnetotactic bacteria. The instrument can also be applied to suspensions of other magnetic cells and magnetic particles. We have ensured that our system, called MagOD, can be easily reproduced by providing the source of the 3D prints for the housing, electronic designs, circuit board layouts, and microcontroller software. We compare the performance of our system to existing adapted commercial spectrophotometers. In addition, we demonstrate its use by analyzing the absorbance of magnetotactic bacteria as a function of their orientation with respect to the light path and their speed of reorientation after the field has been rotated by 90°. We continuously monitored the development of a culture of magnetotactic bacteria over a period of 5 days and measured the development of their velocity distribution over a period of one hour. Even though this dedicated spectrophotometer is relatively simple to construct and cost-effective, a range of magnetic field-dependent parameters can be extracted from suspensions of magnetotactic bacteria. Therefore, this instrument will help the magnetotactic research community to understand and apply this intriguing micro-organism.

Original languageEnglish
Article number094101
JournalReview of scientific instruments
Issue number9
Publication statusPublished - 1 Sept 2022


  • magneto-tactic bacteria
  • optical density


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