Binh Duong

Highly Ordered MnO2 Nanopillars for Enhanced Supercapacitor Performance

This report demonstrates a simple, but efficient method to print highly ordered nanopillars without the use of sacrificial templates or any expensive equipment. The printed polymer structure is used as a scaffold to deposit electrode material (manganese dioxide) for making supercapacitors. The simplicity of the fabrication method together with superior power density and energy density make this supercapacitor electrode very attractive for the next-generation energy storage systems.

Enhanced magnetism in highly ordered magnetite nanoparticle-filled nanohole arrays.

A new approach to develop highly ordered magnetite (Fe3O4) nanoparticle-patterned nanohole arrays with desirable magnetic properties for a variety of technological applications is presented. In this work, the sub-100 nm nanohole arrays are successfully fabricated from a pre-ceramic polymer mold using spin-on nanoprinting (SNAP). These nanoholes a then filled with monodispersed, spherical Fe3O4 nanoparticles of about 10 nm diameter using a novel magnetic drag and drop procedure. The nanohole arrays filled with magnetic nanoparticles a imaged using magnetic force microscopy (MFM). Magnetometry and MFM measurements reveal room temperature ferromagnetism in the Fe3O4-filled nanohole arrays, while the as-synthesized Fe3O4 nanoparticles exhibit superparamagnetic behavior. As revealed by MFM measurements, the enhanced magnetism in the Fe3O4-filled nanohole arrays originates mainly from the enhanced magnetic dipole interactions of Fe3 O4 nanoparticles within the nanoholes and between adjacent nanoholes. Nanoparticle filled nanohole arrays can be highly beneficial in magnetic data storage and other applications such as microwave devices and biosensor arrays that require tunable and anisotropic magnetic properties.

Covert thermal barcodes based on phase change nanoparticles

An unmet need is to develop covert barcodes that can be used to track-trace objects, and authenticate documents. This paper describes a new nanoparticle-based covert barcode system, in which a selected panel of solid-to-liquid phase change nanoparticles with discrete and sharp melting peaks is added in a variety of objects such as explosive derivative, drug, polymer, and ink. This method has high labeling capacity owing to the small sizes of nanoparticles, sharp melting peaks, and large scan range of thermal analysis. The thermal barcode can enhance forensic investigation by its technical readiness, structural covertness, and robustness.

Printed sub-100 nm polymer-derived ceramic structures.

We proposed an unconventional fabrication technique called spin-on nanoprinting (SNAP) to generate and transfer sub-100 nm preceramic polymer patterns onto flexible and rigid substrates. The dimensions of printed nanostructures are almost the same as those of the mold, since the ceramic precursor used is a liquid. The printed patterns can be used as a replica for printing second-generation structures using other polymeric materials or they can be further converted to desirable ceramic structures, which are very attractive for high-temperature and harsh environment applications. SNAP is an inexpensive parallel process and requires no special equipment for operation.

Printed Multilayer Microtaggants with Phase Change Nanoparticles for Enhanced Labeling Security

There is an urgent need to develop taggants that can be used to identify objects, prevent fraud, and deter counterfeiting with high reliability, high capacity, and minimal effort. This paper describes a new multilayer covert taggant based on phase change nanoparticles (metals and eutectic alloys). A panel of selected nanoparticles with different melting temperatures have been added in matrix materials together with fluorescent dye and printed on substrates to form micro-/macrofeatures that contain thermal, fluorescence signature, and structural components. The multilayer taggants can greatly enhance security level for many commercial and forensic applications by their extremely large labeling capacity, coding readiness, and covertness.

Mechanical and Morphological Analysis of Cancer Cells on Nanostructured Substrates.

Cancer metastasis is a major cause of cancer-induced deaths in patients. Mimicking nanostructures of an extracellular matrix surrounding cancer cells can provide useful clues for metastasis. This paper compares the morphology, proliferation, spreading, and stiffness of highly aggressive glioblastoma multiforme cancer cells and normal fibroblast cells seeded on a variety of ordered polymeric nanostructures (nanopillars and nanochannels). Both cell lines survive and proliferate on the nanostructured surface and show more similarity on nanostructured surfaces than on flat surfaces. Although both show similar stiffness on the nanochannel surface, glioblastomas are softer, spread to a larger area, and elongate less than fibroblasts. The nanostructured surfaces are useful for in vitro model of an extracellular matrix to study the cancer cell migratory phenotype.

Effect of modular diffraction gratings on absorption in P3HT:PCBM layers

Various gratings with 700 nm feature spacings are patterned on the reverse side of organic solar cell active layers to increase the path length and constrain light to the cell through total internal reflection. The absorption enhancement is studied for 15, 40, and 120 nm active layers. We were able to confine 9% of the incident light over the wavelength range of 400-650 nm, with thinner gratings having a greater enhancement potential. The measurement setup utilizing an integrating sphere to fully characterize scattered or diffracted light is also fully described.

Ni-Cu-Zn ferrite prepared by aloe vera plant extract or egg white

ions at octahedral sites [2]. It was suggested recently that some Zn, Ni and Cu ferrites offer superior magnetic properties depending on certain concentration of Ni, Cu, Zn in the ferrites [3]. The present study reports on the effects of Zn, Ni, and Cu concentrations on the structural and magnetic properties of the ferrites prepared by simple, cost-effective, non-toxic sol-gel methods. In this study, either Zn(NO

The Effect of Diffraction Gratings on Absorption in P3HT:PCBM Layers

An integrating sphere is used to measure the absorptance of P3HT:PCBM layers with 700 nm period gratings on the reverse side of the substrate. Gratings that do not exploit TIR adversely affect the absorptance.