In this work, a guided shear horizontal mode surface acoustic wave (SH-SAW) sensor, fabricated by patterning gold (Au) interdigitated electrodes (IDE) on a 64°YX-LiNbO 3 based piezoelectric substrate, was used for the detection of heavy metal compounds. A flow cell, with a reservoir volume of 3 µl, which employs inlet and outlet valves for the microfluidic chamber and polydimethylsiloxane (PDMS) based microfluidic channels, was also designed and fabricated using an acrylic material. The frequency based response of the SAW sensor towards varying concentrations of heavy metal compounds such as lead nitrate (PbNO 3) and cadmium nitrate (CdNO 3) were investigated. As the surface acoustic wave propagates on the substrate, between input and output IDEs, a shift in the resonant frequency of the SAW device was observed due to the change in velocity of the wave caused by the varying concentrations of the test analytes. The results obtained demonstrated the capability of the system to detect picomolar level concentrations. The response of the SAW sensor is analyzed and presented in this paper.

Abstract-A flexible electrochemical sensor was screen printed on polyethylene terephthalate (PET). Carbon and silver based inks were used for metallization of the working, counter and reference electrodes. 1,10-phenanthroline and its derivative naphtho[2,3-a]dipyrido[3,2-h:2',3'-f]phenazine-5,18-dione (QDPPZ) was synthesized as sensitive layers for Hg 2+ and Pb 2+ , respectively. Cyclic voltammetry response of the sensor resulted in reduction peaks at 0.2 eV and -0.6 eV for selective detection of Hg 2+ and Pb 2+ , respectively. An 87 % and 9 % change in the average peak currents were observed for the 50 µM concentration of Pb 2+ and Hg 2+ , respectively, against a reference signal established for deionized water (DI). The response of the electrochemical sensor demonstrated the use of traditional printing processes and synthesized chemicals for the selective detection of heavy metal ions.

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In this study, a shear horizontal mode surface acoustic wave (SH-SAW) sensor, was designed and fabricated for the detection of heavy metals. The SH-SAW sensor was photolithographically fabricated by patterning gold (Au) interdigitated electrodes (IDE) and reflectors on the surface of a 64° YX-LiNbO 3 based piezoelectric substrate. A flow cell, with a reservoir volume of 3 µl, which employs inlet and outlet ports for the microfluidic chamber and polydimethylsiloxane (PDMS) based microfluidic channels, was also designed and fabricated using acrylic material. Phenol and naphtho[2,3-a]dipyrido[3,2-h:2'3'-f] phenazine-5,18-dione (QDPPZ) were employed as the sensing layers for mercury and nickel ions, respectively. The frequency based response of the SH-SAW sensor demonstrated picomolar level detection for mercury nitrate (Hg(NO 3 ) 2 ) and nickel nitrate (Ni(NO 3 ) 2 ).

The design and synthesis of well-defined metallic and bimetallic nanoparticles (NPs), their characterization, and the assessment of how their size and shape-dependent properties influence their applications are important areas of investigation for advancing green technologies that protect the environment. This chapter reviews recent advances in the design and synthesis of metallic, bimetallic and semiconductor nanoparticles and their emerging applications in the production of energy and chemicals from biorenewable materials. This contribution focuses on nanoparticle-mediated processes for biomass transformation that include hydrogenation, hydrogenolysis, decarboxylation, small molecule oxidation, conversion of cellulosic materials, hydrocarbon formation, and production of fuel cells. These processes all have significant potential for development of green technologies.