Enhancing performance in optical sensing with magnetic nanoparticles

Magnetic optical sensor particles (MOSePs) allow in situ sensor spot formation by separating the dye-loaded particles in the field of view (FOV) of e.g. an optical fiber. In order to further improve the suitability of magnetic optical sensors, we constructed optimized magnetic separators with an optical window. The combination of these new separators with the concept of magnetic sensor particles enabled oxygen sensing at particle concentrations below 1 mg l−1. In addition to the application in a stirred flask, we demonstrated the concept of magnetic separation for in situ sensor spot formation in 24-well plates by modifying a commercially available SensorDish reader. Finally, we introduce in this article a new technique for the low-cost production of MOSePs, i.e. spray-drying. With this, we produced MOSePs with 100 times increased brightness and almost linear Stern–Volmer correlation between pO2=0 and 1013 hPa.