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.
We have recently demonstrated a simple and low-cost fabrication technique, called low one-photon absorption direct laser writing, to realize desired polymeric microstructures. We present the use of this technique for fabrication of three-dimensional magnetophotonic devices on a photocurable homogeneous nanocomposite consisting of magnetite (Fe3O4) nanoparticles and a commercial SU8 photoresist. The fabricated magnetophotonic microstructures show strong response to an applied external magnetic field. Thus, various three-dimensional submicromechanical magnetophotonic devices, which can be mechanically driven by magnetic force, are designed and created. Potential applications of these devices are also discussed.
We report on the linear electro-optical scattering response from individual ferroelectric (KTiOPO4) nano-crystals. The newly developed Pockels Linear Electro-Optical Microscopy (PLEOM)1-3 is used in this context to map the second-order susceptibility χ(2) of non-centrosymmetric materials with a high sensitivity due to a stabilized interferometric homodyne detection. The random spatial orientation of single nano-crystals (with an average size of 150 nm), together with the orientation of the electric dipole moment of ferroelectric domains can be jointly inferred from the intensity polarization plots together with phase of the linear electro-optical response. Down- scaling the electro-optic response to nano-crystals opens-up new applications towards sub-diffraction electro-optic nano-labels for nonlinear microscopy with applications to nano-sciences and biophotonics. By using a low power He-Ne laser source and a low intensity illumination beam, PLEOM bears the potential of a new low-cost non-imaging method in biology, especially relevant for sensitive samples.
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