We present a PDMS micromolded gas chromatography system on chip with integrated gas sample injection, heating elements, as well as a nanomaterial based chemiresistor array for gas detection.This device is the first realization of a micromolded (as opposed to etched) microscale gas chromatography (µGC) system.The PDMS mold serves the dual purpose of creating the column geometry as well as acting as the stationary phase during the gas chromatography analysis.A glass wafer acts not only to seal to column but also as a platform for a micropatterned detector and heating element.A chemiresitor array consisting of carbon nanotubes (CNT), vanadium oxide nanowires (VO x ) and reduced graphene oxide (rGO) provide cross-calibrated detection of gas constituents after chromatographic separation to yield a multiparameter gas analysis.

Vanadium oxide, manganese oxide, tungsten oxide, and nickel oxide nanowires were investigated for their applicability as chemiresistive gas sensors. Nanowires have excellent surface-to-volume ratios which yield higher sensitivities than bulk materials. Sensing elements consisting of these materials were assembled in an array to create an electronic nose platform. Dielectrophoresis was used to position the nanomaterials onto a microfabricated array of electrodes, which was subsequently mounted onto a leadless chip carrier and printed circuit board for rapid testing. Samples were tested in an enclosed chamber with vapors of acetone, isopropanol, methanol, and aqueous ammonia. The change in resistance of each assembly was measured. Responses varied between nanowire compositions, each demonstrating unique and repeatable responses to different gases; this enabled direct detection of the gases from the ensemble response. Sensitivities were calculated based on the fractional resistance change in a saturated environment and ranged from 6 x 10(-4) to 2 x 10(-5)% change ppm(-1).

We propose a “CMOS for nanoassembly” method to assemble carbon nanotubes and graphene on CMOS chip for gas sensing application. CNT's and graphene have been demonstrated as extremely sensitive chemiresistors for a wide range of analytes. The upper metal layers of the CMOS chip contain sixty electrodes of both planar and three-dimensional geometries. Each electrode is addressable through on chip circuitry. The electrodes are fully exposed by post-process dry etching. Chemiresistive assemblies of nanoscale single wall carbon nanotubes (SWNTs) and reduced graphene oxide (rGO) flakes are assembled onto the exposed electrodes by controlled dielectrophoresis (DEP), which is the motion of a polarizable particle in a dielectric medium. The utility of the platform is shown for gas sensing. To the best of our knowledge, this is the first time functional graphene and carbon nanotubes sensor elements have been integrated onto a single CMOS chip. Previous results indicate that the expansion of the chip to include other chemiresistive nanomaterials is entirely feasible.

This paper presents a new “paint-on” method for low-cost, large-scale fabrication of metamaterials. Specifically, latex paint, silver conducting ink, and regular copy paper are used to create a perfect absorber working at X-band frequencies. The fabricated metamaterial is symmetrical and arranged in a cross-dipole like structure, making it polarization insensitive. Simulation results show absorbency depths of over 90% and near perfect reflection at all other frequencies. These results are obtained using a sandwiched layer of paint (insulator) between two paint conductor metallic planes made from silver ink, one of which contains the cross-dipoles. The approach demonstrates the viability of this new manufacturing method as a new way to create low-cost, large-scale high-performance meta-materials for a wide-range of real world applications. Material measurement and construction techniques are documented in addition to suggestions for improvement

Two of the biggest losses in conventional solar cells are reflections and carrier thermalization. The nanowire geometry presented here has the potential to mitigate both of these losses [1, 2], however it requires nonconventional and non-planer fabrication procedures. Presented here is a facile synthesis of nanowire array solar cells consisting of a metal oxide heterojunction. The nanowires consist of a core-shell geometry consisting of coaxial layers of copper, copper oxide, zinc oxide, and indium tin oxide: these layers correspond to the bottom contact, p-layer, n-layer, and top contact, respectively.

We design, fabricate, and characterize terahertz (THz) resonant metamaterials on parylene free-standing thin film substrates. Several different metamaterials are investigated and our results show strong electromagnetic responses at THz frequencies ranging from 500 GHz to 2.5 THz. The complex frequency dependent dielectric properties of parylene are determined from inversion of reflection and transmission data, thus indicating that parylene is an ideal low loss substrate or coating material. The biostable and biocompatible properties of parylene coupled with the multifunctional exotic properties of metamaterials indicate great potential for medical purposes such as THz imaging for skin cancer detection.

Solar cells are a promising, green energy source; however, cost and efficiency limitations prevent widespread adoption. This paper proposes a solar cell design that is cost-effective both in production and materials. The junction is made of copper (I) oxide and zinc oxide, which are oxides of earth-abundant metals. Furthermore, a wet chemistry fabrication process is used, making the production of such cells inexpensive and easily scalable. The process involves growing copper nanowires, plating zinc, oxidizing, and depositing a top contact. This is a greener manufacturing method of solar cells where no harmful compounds or excessive energy is used in fabrication.