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The microsecond spark discharge plasma jet is experimentally analyzed, experimentally and numerical modeling is performed. It is shown that discharge appears as a the number of microdischarges resulting in the average gas temperature of the jet of about 40 °C-50 °C. Fast imaging and numerical modeling are performed in order to study the discharge development on both microsecond and nanosecond time scales. The biochemical study of the production and the delivery of reactive oxygen and nitrogen species ( H2O2, NO, O2-, “singlet” oxygen, and ONOO-) into liquid phase is performed using fluorescent dyes. [ABSTRACT FROM PUBLISHER]

In this paper, a novel device for sensing perturbations imposed to liquid media contained in a disposable housing is addressed. The device consists of a glass beaker filled with deionized water surrounding a small volume of ferrofluid; a permanent magnet is used to fix the position of the ferrofluidic mass in a compliant position and to generate spikes due to the Rosensweig effect. The effect of external stimuli on the beaker can be estimated by measuring the perturbation produced on the ferrofluidic mass. The latter strategy allows reducing drawbacks related to static friction of conventional inertial devices. The ferrofluid perturbations are monitored by two external planar coils in a differential configuration. The main features of the proposed strategy are structural decoupling between the electric read-out system and beaker housing, which allows both implementing noninvasive measurement in liquid media and making the architecture partially disposable, of low cost, and suitable for real applications. [ABSTRACT FROM AUTHOR]

Up to now, the success of the design of quartz crystal-controlled oscillators (XCOs) based on high-stability classical configurations for uses as microgravimetric thickness-shear-mode acoustic-wave (TSM-AW) sensors in damping media has strongly depended on the ability and experience of the designer. The conditions of strong damping that quartz experiences imply the necessity to adapt the designs so that the oscillation stays in spite of the reduction of its quality factor. Despite all the efforts developed by various authors, a methodology of the design of electronic circuit oscillators for their use in damping media does not exist yet. This is due to the difficulty of the study of the oscillation condition and its possible optimization as a function of the application. In this paper, we propose a methodology to aid designers in developing TSM-AW sensors for high-resolution microgravimetrical applications in liquid media, such as detection of chemical species, biosensors for molecular recognition, etc. Approaches are presented to carry out sensor oscillators based on the Miller topology. [ABSTRACT FROM AUTHOR]

The use of quartz-crystal oscillators as high-sensitivity microbalance sensors is limited by the frequency noise present in the circuit. To characterize the behavior of the sensors, it is not enough to determine their experimental sensitivity, but, rather, it is essential to study the frequency fluctuations in order to establish the sensor resolution. This is fundamental in the case of oscillators for damping media, because the level of noise rises due to the strong decline of the quality factor of the resonator. In this paper, a comparative study of noise and resolution is presented with respect to the frequency and the quality factor. The study has been made using four oscillators designed to be used in quartz-crystal microbalance sensors in damping media. The four circuits have been designed at increasing frequencies in order to improve the sensitivity or frequency change per unit of measurand. Also, the present theoretical resolution limit or best resolution achievable with a microbalance oscillator using an AT resonator is determined, since this does not depend on frequency. However, when operating in liquid, the damping of the resonator makes the resolution diminish due to a worsening of the quality factor. The relationship between the resolution limit and the frequency and characteristics of the liquid medium is determined. The resolution worsens when the density and viscosity of the liquid is increased. However, in this case, an increase in frequency implies a small increase in resolution. Therefore, we find that when working below the maximum quality factor, for similar values, the resolution can be improved by elevating the work frequency. [ABSTRACT FROM PUBLISHER]