A Remote Noninvasive Thermometer Based on Faraday Rotation of Magnetic Nanoparticles

Magnetic nanoparticles (MNPs) are temperature sensitive, making them useful as probes for measuring cellular temperature. In this article, we propose a remote noninvasive thermometer that replaces a traditional magnetic sensor with linearly polarized light as the transmission medium, utilizing the Faraday rotation of MNPs. This method not only overcomes the limitations of distance on temperature measurement accuracy but also offers strong anti-interference capabilities. Using this thermometer, we measured the cooling process of MNPs within a temperature range of 310–316 K, achieving an estimated temperature root-mean-square error (RMSE) of 0.14 K. This approach shows promise for integration with microscopy systems for temperature imaging of cells or biological tissues, potentially revealing new biological insights.