Mask lithography of 2D fluorescent magneto-photonic microstructures for biomedical and quantum applications

The use of microrobotics in biological systems has attracted much attention due to its diverse functionality and controllable motion. Combining magneto-polymer nanocomposite with fluorescent nanoparticles provides new potentials for micro-machining in biomedicine. Due to their contact-free, remote controllable, and biocompatible properties, iron oxide (Fe₃O₄) nanoparticles have been widely used in magnetic resonance imaging (MRI), cell targeting, and drug delivery, and are considered to be an attractive option in further development of micro- scale systems. The fluorescent properties and high photo-stability of semiconductor nanocrystal quantum dots (QDs) have also shown great potential for bio and quantum applications. This work explores the fabrication and manipulation of bimodel fluorescent-magnetic microstructures on a new photo-patternable composite consisting of colloidal semiconductor nanocrystal QDs (CdSe/CdS), superparamagnetic magnetite nanoparticles (Fe₃O₄), and a commercial SU-8 photoresist. Using a mask optical lithography technique, we fabricated 2D microstructures of various shapes and demonstrated their strong response to an externally applied magnetic field. Linear, rotational, and spinning movements are presented. Photo-radiation fluorescent checking was used to map the location of the QDs within the microstructures and strong fluorescent emitters were characterized. Combining Fe₃O₄ nanoparticles, QDs, and SU-8 polymer into a single complex microstructure contributes to a wide range of applications in biomedicine such as biological-labeling, in vivo cargo transportation, and micro-machining, as well as perspectives in quantum technology.