We report on the design, fabrication and characterization of magnetic nanostructures to create a lattice of magnetic traps with sub-micron period for trapping ultracold atoms. These magnetic nanostructures were fabricated by patterning a Co/Pd multilayered magnetic film grown on a silicon substrate using high precision e-beam lithography and reactive ion etching. The Co/Pd film was chosen for its small grain size and high remanent magnetization and coercivity. The fabricated structures are designed to magnetically trap 87 Rb atoms above the surface of the magnetic film with 1D and 2D (triangular and square) lattice geometries and sub-micron period. Such magnetic lattices can be used for quantum tunneling and quantum simulation experiments, including using geometries and periods that may be inaccessible with optical lattices.

In this paper we demonstrate multilayer fabrication of plasmonic gold nanorod arrays using electron-beam lithography (EBL), and show that this structure could be used for multilayered optical storage media capable of continuous-wave (cw) laser readout. The gold nanorods fabricated using the EBL method are aligned perfectly and homogeneous in size and shape, allowing the polarization response of surface plasmon resonance (SPR) to be observed through ensemble array. This property in turn permits polarization detuned SPR readout possible and other manipulations such as progressively twisted arrays through the multilayers to make cw readout possible through deeper layers without too much extinction loss. The layered gold nanorod arrays are separated by thick spacer layer to enable the optical resolving of individual layers. Using this method, we demonstrated four-fold reduction in extinction loss for cw readout in three-layer structure. The current technique of multilayer fabrication and readout can be useful in 3-dimensional fabrication of plasmonic circuits and structures.

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The nano-textured surface of black silicon can be used as a surface-enhanced Raman scattering (SERS) substrate. Sputtered gold films showed increasing SERS sensitivity for thicknesses from 10 up to 300 nm, with sensitivity growing nonlinearly from around 50 nm until saturation at 500 nm. At 50 nm, a cross over from a discontinuous to a fully percolated film occurs as revealed by morphological and electrical measurements. The roughness of the Au coating increases due to formation of nanocrystallites of gold. Structural characterization of the black-Si needles and their surfaces revealed presence of silicon oxide and fluoride. The sharpest nano-needles had a tip curvature radius of ∼10 nm. SERS recognition of analyte using molecular imprinted gels with tetracycline molecules of two different kinds is demonstrated.

A contiguous carbonate‐rich hydroxyapatite microcoating in a microfluidic device represents a substrate that has chemical and structural similarity to bone mineral. The present work describes a low‐temperature method to deposit a carbonate‐rich hydroxyapatite microcoating on a glass slide and its incorporation within the microchannels of a microfluidic device. A glass slide is covered/masked with polypropylene‐based tape and CaCO3 nanoparticles are deposited on exposed areas by convective self assembly. The precursor CaCO3 is converted to carbonate‐rich hydroxyapatite by dissolution‐recrystallization in phosphate‐buffered saline. The microcoating is aligned/incorporated within a microchannel when the underlying glass is bonded to a polydimethylsiloxane structure with the device layout. X‐ray diffraction, laser Raman microspectroscopy, and X‐ray photoelectron spectroscopy indicate that the microcoating was comprised of carbonate‐rich hydroxyapatite. Scanning electron microscopy and 3D laser confocal microscopy showed that was comprised of nanocrystalline rod‐like clusters that collectively exhibit a thickness of ∼20 µm. Monocultures/cocultures of osteoblast‐lineage (MC3T3‐E1, MG63) and preosteoclast‐lineage (RAW 264.7) cells were performed. Osteoblast‐lineage cells adhered to the microcoating and deposited an extracellular matrix of collagen fibrils and mineral accretions. Mineralization was detected in/near the inlet wells. The microcoating is analogous to bone mineral and could be applied to various layouts and mineral systems.