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

Abstract

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.