In this paper, microstrip-based spiral structured artificial magnetic media (metamaterial) coupled with microfluidic channel is experimentally demonstrated for sensing applications. It is found that the resonant frequency and the amplitude changes due to dielectric loading from the introduction of chemical substances in the microfluidic channels. Different concentrations of water -methanol and water -isopropanol samples are used in the characterization of the sensor. For water -methanol mixtures, the resonant frequency shifts from 2.15 GHz to 2.0 GHz with change in dielectric constant from 25 to 75. Results show that the wave propagation in LH-media can be used for interrogation of minute volumes of samples with high sensitivity. IntroductionRapid characterization of chemical and biological samples is increasingly important in clinical, security, safety, drug discovery and industrial applications. Sensing approaches are needed that does not require tagging, (e.g., using fluorescent markers) in order to maintain the samples in their original form while under study. Along with rapid label-free characterization, interrogation of small sample volumes is critically needed in the areas of clinical diagnosis and drug discovery. In this paper, periodic media co-integrated with microfluidic leading to a novel RF near-field sensor is implemented to tackle these challenges. The proposed sensor is simple, cost effective, and can be used for label-free sensing and detection Spiral structured artificial magnetic media (metamaterial) designs have been widely used in the design of compact coplanar waveguides (CPW) and microstrip-based circuit topologies. Recently, split-ring based metamaterial structures that are edge-coupled to a microstrip line have been used in the sensing of biomolecules [1]. In this structure, the interrogation signal (RF) edge couples from a microstrip transmission line to a ring resonator. The biomolecules are made to bind onto the ring resonator. A direct approach of interrogation will be desirable which is more compact and provides improved sensitivity and yet still simple to fabricate and implement. To meet this goal, in this paper, metamaterial structure that is integral part of the microstrip line is employed for sensing application. A spiral based metamaterial transmission was recently introduced, [2 -3], and this design is implemented here for sensing applications.In spiral based metamaterial transmission lines, the periodic arrays of the spiral structure employ left-handed (LH) propagation properties and support backward waves at their fundamental resonance [2]. Motivated by the wave propagation phenomenon of this medium, a microfluidic sensor that interrogates samples in the near-field region is attractive to achieve high sensitivity using low-volumes of samples. This sensor is designed and implemented for

On the grid side, the half-bridge topology of the microinverter is of interest for solar rooftop applications because of its high efficiency, low component count, and cost-effectiveness. However, it has an inherent double-line frequency ripple voltage on the dc-link, which causes the injection of a third-order harmonic current when the voltage control loop is closed. Furthermore, in practice, different average voltages or different capacitances of the two capacitors at the dc-link produce a second-order harmonic current that flows into the grid. In this paper, the analytical details of these harmonics are comprehensively described, and a simple and effective low-cost technique using the cascaded connection of two modified notch filters is proposed in the voltage control loop to mitigate their effects. The simulation and experimental results of a 300 W microinverter indicate that the proposed filters represent an effective low-cost solution and perform well in accordance with the IEEE 1547 standard, even if the capacitances at the dc-link are mismatched by 20%. Besides, the prototype is tested when occurring of the changing +1% of the line frequency, or appearing of the distorted waveform of grid voltage with the composition of 6% of fifth-order harmonic. Nomenclature Capital boldface italic letters such as V, represent phasors. Capital italic letters such as C 1 , represent constant variables. Small italic letters such as v dc (t), represent instantaneous variables depending on time. Small italic letters such as ṽ dc (t), represent small ac signals in the time domain. Capital italic letters such as G vp (s), represent transfer functions in the s-domain. Small italic letters such as v dc (s), represent signal variables in the s-domain.

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In this paper, a new metamaterial (MTM) unit cell implemented in a microstrip transmission line configuration is proposed. Reconfigurable metamaterial-based Composite Right/Left Handed (CRLH) microstrip transmission line, with one-side etching and no via, is presented here for the first time. As a result, it is easier to fabricate and more convenient for integration. By incorporating varactor diodes, the electrical characteristics of the unit cell can be electronically reconfigured through DC voltage tuning. A microstrip line loaded with this new unit cell exhibits a tunable band pass characteristics with right-and left-handed phenomena. This was confirmed using a dispersion diagram. A simple tunable band-pass (7 -8.25 GHz) filter using the new unit cell is demonstrated. A single unit cell circuit has been fabricated and preliminary measured results correlate closely with simulation results.

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