Tracking of Magnetic Micromotors in Confined Channels Through Scattering Tissue

The field of small-scale microdevices is growing rapidly towards the development of tethered/untethered microsensors and therapeutic agents that can move through narrow vascular networks in living organisms to diagnose and treat for example vascular diseases. However, imaging and localization of such microdevices are challenging under scattering tissue due to the lack of high spatial and temporal resolution that compromises the penetration depth and therefore the application scenario. Here, we report the tracking of magnetically-driven rolling micromotors (20 µm in diameter) through scattering tissue (1.2 mm thickness) using reflective infrared (IR) imaging. This technique provides high spatiotemporal resolution for the tracking of micro-agents in a narrow vascular network. As a potential application, we suggest the use of such micro-agents as micro-viscosimeters, in which by analyzing their dynamics, one can extract some basic information on the surrounding fluid properties which might be related to certain health status.