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Bionanocomposites Staphylococcus aureus /carbon nanotubes were prepared and their biocompatibility with different species of carbon nanotubes (CNTs) evaluated in terms of their incorporation into a microbial fuel cell (MFC) anodic design. Multi wall carbon nanotubes (MWNTs) with various morphologies and structures, as received, and synthesized by the pyrolysis of novolac with ferrocene addition were used. MWNTs were characterized by TEM and FT‐IR spectroscopy. Optical microscopy with fluorescent quantum dots (QDs) have been used for bio‐labeling, microorganisms‐CNTs biocompatibility and rapid identification of the colonies developed. Designed BNCs are good culture cells media and the electrodes based on synthesized CNTs could be used with good effects in MFCs, from the point of view of bacteria biocompatibility. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper, we present microwave filters that are based on 6-nm-thick ferroelectric thin films of hafnium oxide doped with zirconium (HfZrO), which are tunable continuously in targeted bands of interest within the frequency range 0.1–16 GHz, when the applied direct current (DC) voltage is swept between 0 V and 4 V. Here, we exploit the orthorhombic polar phase in HfO2 through a careful doping using zirconium in an Atomic Layer Deposition (ALD) process, in order to guarantee phase stabilization at room temperature. Polarization versus voltage characterization has been carried out, showing a remanent polarization (Pr) of ~0.8 μC/cm2 and the coercive voltage at ~2.6 V. The average roughness has been found to be 0.2 nm for HfZrO films with a thickness of 6 nm. The uniform topography, without holes, and the low surface roughness demonstrate that the composition and the structure of the film are relatively constant in volume. Three filter configurations (low-pass, high-pass, and band-pass) have been designed, modelled, fabricated, and fully characterized in microwaves, showing a frequency shift of the minimum of the reflection coefficient between 90 MHz and 4.4 GHz, with a minimum insertion loss of approximately 6.9 dB in high-pass configuration.

This paper is dedicated to the study of the tunable electromagnetic properties of HfO 2 doped with Zr (further referred to as HfZrO) grown on high-resistivity silicon using atomic layer deposition (ALD) techniques. Two metallic coplanar lines patterned on HfZrO having different lengths have been used to determine the effective permittivity and wave propagation constant in HfZrO in the frequency range 1-14 GHz, hence covering the L, S, C, X and (part of the) K u bands. We have observed a significant modulation of the effective permittivity when a bias voltage is applied within the range 0-5 V, with an almost constant increase of 27% in a frequency range of 8 GHz. We have also extracted the attenuation constant, phase constant and loss tangent: the losses due to the thin HfZrO ferroelectric layer increase of maximum 21% at 5 V, which represents the saturation upper limit for ferroelectric's polarization. These results could have a significant impact on effective design of ferroelectric-based microwave circuits with tunable characteristics.INDEX TERMS Ferroelectric films, microwave measurements, transmission lines, tunable circuits and devices.