Design of an innovative polymerase chain reaction device based on buoyancy driven flow

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Polymerase Chain Reaction (PCR) plays a central role in the field of molecular biology. The miniaturization of PCR systems is promising as it potentially minimizes costly reagent consumption and time required for analysis. In PCR microdevices a sample solution is usually handled by external pumps. An alternative solution relies on temperature-induced density difference in the presence of a body force to induce buoyancy driven flow. This alternative method is easy to be used and does not require expensive setup, but, to date, the thermo-fluid-dynamic field in the micro-channels still needs to be optimized. The present study focuses on the design of micro-channels, having innovative and optimized shapes to obtain proper fluid actuation and DNA sample amplification within buoyancy driven flow PCR devices. A parametric study is carried out by means of computational thermal fluid dynamic modeling: several channel geometry configurations were compared in terms of time required for analysis, temperature distribution and priming volume. The advantages and disadvantages of such configurations are discussed

Computational and experimental investigation of mixing in microchannels

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Mixing is a key process for the successful of all chemical or biochemical reactions, so effective micromixers represent essential components for micro total analysis systems (μTAS) or lab-on-a-chip. In the present study a combined computational and experimental approach was adopted to evaluate how the efficiency of a Y-mixer can be enhanced by modifying its downstream geometry. Three different geometries were studied and compared: Y-straight channel, Y-sine channel and Y-wrinkled wall channel. For each of them the influence of perfusing flow rates and channel cross section aspect ratio was investigated. Physical prototypes were built using a simple technique based on a xerographic process, and their mixing performance was experimentally evaluated. Computational models of the designed micromixers were generated: the Navier-Stokes equations for an incompressible Newtonian fluid and the advection-diffusion equation were solved with an uncoupled approach by means of the finite volume method. The computational and experimental results were critically compared, revealing Y-wrinkled wall mixer as the best performer among those considered and suggesting criteria of possible improvements and optimization

Numerical simulation of a deformable cell in microchannels

The main goal of this work is to numerically investigate the behavior of a cell flowing in a microfluidic system. In particular, we want to model flow-induced deformations of an isolated cell to quantitatively evaluate the cell response when subjected to a representative range of flow rates in a realistic geometry, with specific interest in the case of cell trapping. This research will help optimize operating conditions as well as the design of cell manipulation/culture micro-devices, so as to guarantee cell viability and ultimately improve high-throughput performance

Design of an air-flow microchamber for microparticles detec

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.A novel device, able to funnel a suspension of micrometric particles in air into a microchamber equipped with a capacitive sensor, has been designed for the detection and characterization of particulate matter (PM) in air. Numerical simulations have been performed to predict the trajectory of the microparticles through the PDMS microchamber where the sensor is located. The feasibility of detecting single PM10 particles has been demonstrated by our experiments, where sequences of single industrial talc particles (average diameter of 8 μm) have been detected and counted by a capacitive sensor. Our results indicate that radical miniaturization of air quality monitors is possible and, therefore, pervasive monitoring of air pollution will be soon feasible

µ-Particle tracking velocimetry and computational fluid dynamics study of cell seeding within a 3D porous scaffold

Cell seeding of 3D scaffolds is a critical step in tissue engineering since the final tissue properties are related to the initial cell distribution and density within the scaffold unit. Perfusion systems can transport cells to the scaffold however; the fact that cells flow inside the scaffold pores does not guarantee cell deposition onto the scaffold substrate and cell attachment. The aim of this study was to investigate how fluid flow conditions modulate cell motion and deposition during perfusion. For such a purpose, a multiphase-based computational fluid dynamics (CFD) model was developed in conjunction with particle tracking velocimetry experiments (PTV) which for the first time were applied to observe cell seeding inside a 3D scaffold. CFD and PTV results showed the strong effect of gravity for lower flow rates leading to cell sedimentation and poor transport of cells to the scaffold. Higher flow rates help overcome the effect of gravity so more cells travelling inside the scaffold were found. Nonetheless, fluid flow drags cells along the fluid streamlines without intercepting the scaffold substrate. As a consequence, if cells do not deposit into the scaffold substrate, cell adhesion cannot occur. Therefore, cell-scaffold interception should be promoted and the present computational model which predicts the effect of gravity and fluid drag on cells trajectories could serve to optimise bioreactors and enhance cell seeding efficiency

Una Experiencia de Prevención del Acoso Entre Pares en Niños Escolarizados

En el presente trabajo se presenta la experiencia de capacitación con docentes y directivos en relación a la prevención del acoso entre pares (presencial y virtual) en niños de Escuelas Municipales de la ciudad de Córdoba. Se adopta el enfoque de educación en habilidades para la vida como estrategia para la construcción de una convivencia saludable en el ámbito escolar, en consonancia con los lineamientos formulados por la Organización Panamericana de la Salud (2001), la cual recomienda que los programas escolares integren al currículo los conocimientos, valores y habilidades necesarias para el desarrollo de estilos de vida saludable. Sensibilizar y concienciar a los docentes sobre la necesidad de intervenir y desarrollar actuaciones para fortalecer habilidades interpersonales y de la comunicación como forma de reducción y prevención del acoso entre pares. La experiencia se abordó desde la metodología de Investigación Acción Participativa. Se desarrollaron 4 encuentros con modalidad de jornada taller de 4 horas cada uno. Participaron 45 docentes y 60 directivos. Los participantes discriminan conductas de riesgos en relación al acoso entre pares de aquellas acciones que favorecerían la salud y convivencia; destacaron la importancia de favorecer la comunicación; proponen el trabajo cooperativo, fomentando la solidaridad; reconocen la problemática del acoso entre pares y su incidencia en edades tempranas. El trabajo demuestra que el docente, en la medida que fortalece en los alumnos diferentes habilidades interpersonales y de la comunicación, potencia la construcción de vínculos solidarios orientados a la convivencia saludable a nivel escolar, familiar y comunitario

Obstetric near-miss cases among women admitted to intensive care units in Italy

Objective. Maternal near-miss defines a narrow category of morbidity encompassing potentially life-threatening episodes. The purpose of this study was to detect near-miss instances among women admitted to intensive care units or coronary units, analyze associated causes, and compute absolute and specific maternal morbidity rates in six Italian regions. Design. Observational retrospective study. Setting. Six Italian regions representing 49% of all resident Italian women aged 15-49 years. Population. The study population included all pregnant women aged 15-49 years admitted to intensive care units or coronary care units in the participating regions. Cases were defined as women aged 15-49 years resident in the participating regions, with one or more hospitalizations in intensive care for pregnancy or any pregnancy outcome between 2004 and 2005. Methods. Cases were identified through the Hospital Discharge Database. Enrolled cases were diagnosed according to the 9th International Classification of Diseases. Main outcome measure. Maternal near-miss rate (number of women experiencing an admission to intensive care units/all women with live or stillborn babies). Results. A total of 1259 near-miss cases were identified and the total maternal near-miss rate was 2.0/1000 deliveries. Seventy percent of the women were admitted to intensive care units or coronary units after a cesarean section. The leading associated risk factors were obstetric hemorrhage/disseminated intravascular coagulation (40%) and hypertensive disorders of pregnancy (29%). Conclusions. Monitoring of near-miss morbidity in conjunction with mortality surveillance could help to identify effective preventive measures for potentially life-threatening episodes