High Resolution Viscosity Measurement by Thermal Noise Detection

An interferometric method is implemented in order to accurately assess the thermal fluctuations of a micro-cantilever sensor in liquid environments. The power spectrum density (PSD) of thermal fluctuations together with Sader's model of the cantilever allow for the indirect measurement of the liquid viscosity with good accuracy. The good quality of the deflection signal and the characteristic low noise of the instrument allow for the detection and corrections of drawbacks due to both the cantilever shape irregularities and the uncertainties on the position of the laser spot at the fluctuating end of the cantilever. Variation of viscosity below 0.03 mPa$\cdot$s was detected with the alternative to achieve measurements with a volume as low as 50 $\mu$L.Comment: Sensors, MDPI, 201

Fractal analysis reveals functional unit of ventilation in the lung

Ventilation is inhomogeneous in the lungs across species. It has been hypothesized that ventilation inhomogeneity is largely determined by the design of the airway branching network. Because exchange of gases at the alveolar barrier is more efficient when gas concentrations are evenly distributed at subacinar length scales, it is assumed that a 'functional unit' of ventilation exists within the lung periphery, where gas concentration becomes uniform. On the other hand, because the morphology of pulmonary airways and alveoli, and the distribution of inhaled fluorescent particles show self-similar fractal properties over a wide range of length scales, it has been predicted that fractal dimension of ventilation approaches unity within an internally homogeneous functional unit of ventilation. However, the existence of such a functional unit has never been demonstrated experimentally due to lack of in situ gas concentration measurements of sufficient spatial resolution in the periphery of a complex bifurcating network. Here, using energy-subtractive synchrotron radiation tomography, we measured the distribution of an inert gas (Xe) in the in vivo rabbit lung during Xe wash-in breathing manoeuvres. The effects of convective flow rate, diffusion and cardiac motion were also assessed. Fractal analysis of resulting gas concentration and tissue density maps revealed that fractal dimension was always smaller for Xe than for tissue density, and that only for the gas, a length scale existed where fractal dimension approached unity. The length scale where this occurred was seen to correspond to that of a rabbit acinus, the terminal structure comprising only alveolated airways. Key points Gas ventilation is inhomogeneous in the lung of many species. However, it is not known down to what length scales this inhomogeneity persists. It is generally assumed that ventilation becomes homogeneous at subacinar length scales, beyond the spatial resolution of commonly available imaging techniques, hence this has not been demonstrated experimentally. Here we measured the distribution of inhaled Xe gas in the rabbit lung using synchrotron radiation energy-subtractive imaging and used fractal analysis to show that ventilation becomes internally uniform within regions about the size of rabbit lung acini.Peer reviewe

Lithium niobate micromachining for the fabrication of microfluidic droplet generators

In this paper, we present the first microfluidic junctions for droplet generation directly engraved on lithium niobate crystals by micromachining techniques, preparatory to a fully integrated opto-microfluidics lab-on-chip system. In particular, laser ablation technique and the mechanical micromachining technique are exploited to realise microfluidic channels in T-and cross junction configurations. The quality of both lateral and bottom surfaces of the channels are therefore compared together with a detailed study of their roughness measured by means of atomic force microscopy in order to evaluate the final performance achievable in an optofluidic device. Finally, the microfluidics performances of these water-in-oil droplets generators are investigated depending on these micromachining techniques, with particular focus on a wide range of droplet generation rates

Lithium Niobate Optical Waveguides and Microwaveguides

Lithium niobate has attracted much attention since the 1970s due to its capacity to modify the light by means of an electric control. In this chapter, we review the evolution of electro-optical (EO) lithium niobate waveguides throughout the years, from Ti-indiffused waveguides to photonic crystals. The race toward ever smaller EO components with ever-lower optical losses and power consumption has stimulated numerous studies, the challenge consisting of strongly confining the light while preserving low losses. We show how waveguides have evolved toward ridges or thin film-based microguides to increase the EO efficiency and reduce the driving voltage. In particular, a focus is made on an easy-to-implement technique using a circular precision saw to produce thin ridge waveguides or suspended membranes with low losses

LiNbO3 ridge waveguides realized by precision dicing on silicon for high efficiency second harmonic generation

Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are carved with only use of a precision dicing machine without need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. Influence of geometrical non uniformities of waveguides due to fabrication process is asserted. Components characteristics are studied notably their robustness and tunability versus temperature.Comment: 10 pages, 10 figure

Multiobjective Optimization Using Goal Programming for Industrial Water Network Design

The multiobjective optimization (MOO) of industrial water networks through goal programming is studied using a mixed-integer linear programming (MILP) formulation. First, the efficiency of goal programming for solving MOO problems is demonstrated with an introductive mathematical example and then with industrial water and energy networks design problems, formerly tackled in literature with other MOO methods. The first industrial water network case study is composed of 10 processes, 1 contaminant, and 1 water regeneration unit. The second, a more complex real industrial case study, is made of 12 processes, 1 contaminant, 4 water regeneration units, and the addition of temperature requirements for each process, which implies the introduction of energy networks alongside water networks. For MOO purposes, several antagonist objective functions are considered according to the case, such as total freshwater flow rate, number of connections, and total energy consumption. The MOO methodology proposed is demonstrated to be very reliable as an a priori method, by providing Pareto-optimal compromise solutions in significant less time compared to other traditional methods for MOO

LiNbO3 integrated system for opto-microfluidic sensing

International audience; In this work, we realized and tested an integrated opto-microfluidics platform entirely made on lithium niobate (LiNbO3) crystals, able to detect the single droplet passage and estimate its size without the need of any imaging processing. It is based on the coupling of a self-aligned integrated optical stage, made of an array of optical waveguides, to a microfluidic circuit such as a T-junction or Cross-junction engraved in the same substrate. The platform presented high quality performances in terms of optical triggering, reproducibility and stability in time, allowing in real-time data analysis. The comparison with standard approaches using microscopes and fast camera imagining acquisition and relative post-processing, showed an increased capability better than 50%. The demonstrated feasibility of integration of these two stages will allow the realization of a Lab-On-a-Chip on a monolithic substrate of lithium niobate, exploiting its multiple applications for manipulation of droplets

Water integration in eco-industrial parks using a multi-leader-follower approach.

The design and optimization of industrial water networks in eco-industrial parks are studied by formulating and solving multi-leader-follower game problems. The methodology is explained by demonstrating its advantages against multi-objective optimization approaches. Several formulations and solution methods for MLFG are discussed in detail. The approach is validated on a case study of water integration in EIP without and with regeneration units. In the latter, multi-leader-single-follower and single-leader-multi-follower games are studied. Each enterprise's objective is to minimize the total annualized cost, while the EIP authority objective is to minimize the consumption of freshwater within the ecopark. The MLFG is transformed into a MOPEC and solved using GAMS® as an NLP. Obtained results are compared against the MOO approach and between different MLFG formulations. The methodology proposed is proved to be very reliable in multi-criteria scenarios compared to MOO approaches, providing numerical Nash equilibrium solutions and specifically in EIP design and optimization

Benefits analysis of optimal design of eco-industrial parks through life cycle indicators

Industrial symbiosis offers to companies the possibility to make economic benefits and to minimize environmental impacts by sharing flows and increasing inter-enterprise exchanges. However, even if some studies have demonstrated the benefits of the development of eco-industrial parks (EIP), there is no consensus to evaluate their benefits in a global point of view and there is a lack of integrated indicators for the assessment of EIPs. The aim of this study is to propose a holistic approach to evaluate the global impacts of an EIP. To reach this goal, the potential eco-industrial park of Mongstad in Norway has been chosen. Several steps are considered: a simulation through Aspen Properties®, then the superstructure optimization problem solved within GAMS® environment by minimizing the total cost of the EIP is done. Finally, an evaluation of the optimal solution through a life cycle approach is carried out. The results show that companies included in the EIP have environmental impacts reduced from 45% to 80% compared to the impacts of stand-alone companies