Modeling and Experimental Investigation of Resonant Viscosity and Mass Density Sensors Considering their Cross-Sensitivity to Temperature

AbstractIn this contribution we discuss a generalized, reduced order model for resonant viscosity and mass density sensors which considers also the devices’ cross sensitivities to temperature. The applicability of the model is substantiated by experimental results from measurements obtained with a circular steel tuning fork in various liquids and temperatures. Advantages of this model are its simplicity, its general applicability for resonant mass density and viscosity sensors which furthermore facilitates the comparison of different sensors

Resonant Steel Tuning Forks for Precise Inline Viscosity and Mass Density Measurements in Harsh Environments

AbstractThe principle of using steel tuning forks for viscosity and mass density measurements is investigated. From recorded frequency responses of fully immersed tuning forks, resonance frequencies and quality factors are evaluated and related to the liquids mass densities and viscosities. The benefit of these resonators is their mechanical rigidity which allows the application in harsh environments and mechanical cleaning processes without detuning or damaging the device. The setup was particularly devised that only the resonator itself but no excitation or read-out mechanisms get wetted by the sample liquid. The results obtained with a circular cross-sectioned tuning fork in different liquids are shown and discussed

Application of Resonant Steel Tuning Forks with Circular and Rectangular Cross Sections for Precise Mass Density and Viscosity Measurements

International audienceThe feasibility of using commercially available steel tuning forks for viscosity and mass density sensing is investigated. For this task, the tuning forks are electromagnetically driven and read out to record their frequency responses containing the fundamental resonant mode upon immersion in a sample liquid. Evaluated resonance frequencies and quality factors are then related to the liquids' mass density and viscositiy. The used electromagnetic actuation and readout principle allows that only the tuning fork which is placed in the center of a glass tube gets wetted with the liquid to be examined. All excitation and read out related structures and electronics are placed outside the glass tube and thus, are not affected or influenced by the liquid. A generalized model relating evaluated quality factors and resonance frequencies to viscosity and mass density is used to describe the tuning forks' sensitivities and furthermore to estimate required stabilities of apparent quality factors and resonance frequencies to achieve measurement accuracies similar to those of laboratory instruments. It is shown that relative accuracies in the order of 1 % in viscosity and and 0.1 mg/cm 3 in mass density are achievable

On-line reversed-phase liquid chromatography x supercritical fluid chromatography coupled to high-resolution mass spectrometry: A powerful tool for the characterization of advanced biofuels

International audienceBio-oils obtained by thermochemical or biochemical conversion of biomass represent a promising source of energy to complement fossil fuels, in particular for maritime or air transport for which the use of hydrogen or electricity appears complicated. As these bio-oils are very rich in water and heteroatoms, additional treatments are necessary before they can be used as biofuel. In order to improve the efficiency of these treatments, it is important to have a thorough knowledge of the composition of the bio-oil. The characterization of bio-oils is difficult because they are very complex mixtures with thousands of compounds covering a very wide range of molecular weight and polarity. Due to the high degree of orthogonality between the two chromatographic dimensions, the on-line combination of reversed-phase liquid chromatography and supercritical fluid chromatography (on-line RPLC x SFC) can significantly improve the characterization of such complex matrices. The hyphenation was optimized by selecting, in SFC, the stationary phase, the co-solvent, the make-up solvent prior to high resolution mass spectrometry (HRMS) and the injection solvent. Additionally, a new interface configuration is described. Quality descriptors such as the occupation of the separation space, the peak shapes and the signal intensity were considered to determine the optimal conditions. The best results were obtained with bare silica, a co-solvent composed of acetonitrile and methanol (50/50, v/v), a make-up solvent composed of methanol (90%) and water (10%) with formic acid (0.1%), an addition of co-solvent through an additional pump for SFC separation in a 2.1 mm column, and an hydro-organic solvent as injection solvent. The optimized setup was used to analyze two microalgae bio-oils: the full bio-oil coming from hydrothermal liquefaction and Soxhlet extraction of microalgae, and the gasoline cut obtained after distillation of the full bio-oil. Results in on-line RPLC x SFC-qTOF were particularly interesting, with very good peak shapes and high reproducibility. Moreover, the high degree of orthogonality for microalgae bio-oils of RPLC and SFC was highlighted by the very large occupation of the separation space. Isomeric profiles of compound families could be obtained in RPLC x SFC-qTOF and many isomers not separated in SFC alone were separated in RPLC and vice versa, thus showing the complementarity of the two chromatographic techniques

Simple fabrication process for organic piezoelectric resonators : application to viscosity measurement

International audienceSilicon-based Micro Electro Mechanical Systems (MEMS) success is incontestable as they are widely present in new technologies. However, technologies based on organic electronics are emerging because they are more interesting in terms of fabrication costs, with a large panel of functional properties, and are very attractive for flexible devices. In this context, organic piezoelectric resonators based on a simple low-cost fabrication process are presented in this work for viscosity sensing. It shows the potential of organic resonators in liquid media for biological and chemical sensing

Collaborative study of a Supercritical Fluid Chromatography method for the determination of pharmaceutical impurities

Projet PHAR