Tara Dalton

This investigation concerns the application of different techniques, including optical fiber strain sensing, pulsed Digital Speckle Pattern Interferometry (DSPI), traditional modal analysis and finite element model updating procedures to the study of vibrating composite structures. A prototype system for condition monitoring of composite structures is being developed which relies on the on-line measurement of dynamic strains in order to detect

This investigation concerns the application of different techniques, including optical fibre strain sensing, pulsed Digital Speckle Pattern Interferometry (DSPI), traditional modal analysis and finite element modeling to the study of vibrating composite structures. A prototype system for condition monitoring of composite structures is being developed which relies on the on-line measurement of dynamic strains in order to detect any deterioration in performance due to the accumulation of damage. A range of carbon-fibre reinforced composite specimens that incorporate innovative Fabry-Perot interferometric long gauge-length strain sensors have been produced and tested. The optimal design of fibre sensor network configurations for the identification of different damage parameters is being aided through the development of a software simulation tool and the use of a p-version FEM package. Vibration modes of the excited structures have also been determined using an out-of-plane pulsed-DSPI system, employing a dual-cavity frequency-doubled Nd:YAG pulsed laser with a 25 Hz repetition rate. In general, experimental results compare favorably with finite element predictions. The data derived from the strain sensors is used to update a parameterized FE model of the composite structure, allowing the determination of the position and extent of damage present.

... maurice.whela@jrc.it 3 Stokes Research Institute, University of Limerick, Limerick, Ireland; phone +353 61 202961,fax +353 61 202393; tara.dalton@ul.ie ... Together with Bragg grating point sensors, an innovative Fabry-Perot interferometric long gauge strain sensor is proposed. ...

ABSTRACT Superhydrophobic surfaces combine roughness features with low energy surfaces to create materials with substantially decreased wettability and reduced drag resistance in laminar flows. These characteristics make superhydrophobic surfaces a promising technology for reducing the flow resistance of microchannels in a variety of applications, including thermal management and biofluidics. The presence of a gas layer that is trapped within the superhydrophobic surface, and which separates the majority of the microchannel wall from the working fluid, gives rise to a low shear-stress region responsible for the observed reduction in flow resistance. Although there have been numerous experimental and computational studies of fluid flow in superhydrophobic microchannels, to our knowledge no predictive analytical model capturing the essential features of the flow has been developed for the case of post-type surface roughness. In this work we propose the use of porous flow theory to predict the behavior of the fully-developed inertia-less flow of a constant viscosity Newtonian fluid in a parallel-plate, super-hydrophobic microchannel whose roughness features are composed of a square array of posts arranged transverse to the flow. The volume-averaged Navier-Stokes (VANS) equation is used to model the flow behavior in both the open and porous regions, taking into account the presence of a recirculating gas layer and the potential for partial liquid penetration into the porous region. The fluid motion in the porous and non-porous regions is coupled by imposing boundary conditions specifying the continuity of velocity and a stress jump at the interface between the two regions. An empirical factor, known as the stress jump coefficient β, appears in the stress jump boundary condition and is shown to be correlated to the geometric properties of the porous region via a scaling law inferred from non-dimensional analysis and observed in 3D computational fluid dynamics simulations. Finally, the predictions of the model are compared with existing experimental studies.

The thermal management of electronics is becoming an increasing concern as industry continues to simultaneously push performance while shrinking the size of electronic devices. Microchannel cooling is a promising technology to accommodate the heat dissipation rates and associated fluxes projected for future generations of electronics while also satisfying the need for a reduced footprint to accommodate ever-shrinking device sizes. One

This investigation concerns the application of different techniques, including optical fibre strain sensing, pulsed Digital Speckle Pattern Interferometry (DSPI), traditional modal analysis and finite element modeling to the study of vibrating composite structures. A prototype system for condition monitoring of composite structures is being developed which relies on the on-line measurement of dynamic strains in order to detect any deterioration in performance due to the accumulation of damage. A range of carbon-fibre reinforced composite specimens that incorporate innovative Fabry-Perot interferometric long gauge-length strain sensors have been produced and tested. The optimal design of fibre sensor network configurations for the identification of different damage parameters is being aided through the development of a software simulation tool and the use of a p-version FEM package. Vibration modes of the excited structures have also been determined using an out-of-plane pulsed-DSPI ...

Heat Transfer and Thermal Management have become important aspects of the developing field of μTAS systems particularly in the application of the μTAS philosophy to thermally driven analysis techniques such as PCR. Due to the development of flowing PCR thermocyclers in the field of μTAS, the authors have previously developed a melting curve analysis technique that is compatible with these

This paper is the first in a two-part study of the pressure-flow characteristics for a range of microchannels. Here, the manufacture of the channels and the resulting quality in terms of the channels' closeness to target dimensions, channel-to-channel variation for each sample, ...

Continuous-flow analysis, where samples circulate encapsulated in a carrier fluid is an attractive alternative to batch processing for high-throughput devices that use the polymerase chain reaction (PCR). Challenges of continuous-flow prototypes include the hydrodynamic and biological incompatibility of the carrier fluid, microchannel fouling, sample carryover and the integration of a nucleic acid extraction and reverse transcription step. We tested two homemade, continuous-flow thermocycler microdevices for amplification of reverse-transcribed messages from cell lysates without nucleic acid extraction. Amplification yield and specificity were assessed with state-of-the-art, real-time quantitative equipment. Carryover contamination between consecutive samples was absent. Amplification specificity and interference by genomic DNA were optimized by primer design. Robust detection of the low-copy transcript CLIC5 from 18 cells per microliter is demonstrated in cultured lymphoblasts. The results prove the concept that the development of micro-total analysis systems (micro-TAS) for continuous gene expression directly from cell suspensions is viable with current technology.

This study investigated the effect of exposing a polymerase chain reaction (PCR) mixture to capillary tubing of different materials and lengths, at different contact times and flow rates and the adsorption of major reaction components into the tubing wall. Using 0.5 mm ID tubing, lengths of 40 cm and residence times up to 45 min, none of the tested polymeric materials was found to affect subsequent PCR amplification. However, after exposure of the mixture to tubing lengths of 3 m or reduction of sample volume, PCR inhibition occurred, increasing with the volume to length ratio. Different flow velocities did not affect PCR yield. When the adsorption of individual PCR components was studied, significant DNA adsorption and even more significant adsorption of the fluorescent dye Sybr Green I was found. The results indicate that PCR inhibition in polymeric tubing results from adsorption of reaction components to wall surfaces, increasing substantially with tubing length or sample volume reduction, but not with contact time or flow velocities typical in dynamic PCR amplification. The data also highlight that chemical compatibility of polymeric capillaries with DNA dyes should be carefully considered for the design of quantitative microfluidic devices.