A volumetric temperature and velocity measurement technique for microfluidics based on luminescence lifetime imaging

Massing, Julian; Kähler, Christian J.; Cierpka, Christian

doi:10.1007/s00348-018-2616-y

Cited by 33 publications

(26 citation statements)

References 43 publications

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“…Segura et al (2015) utilized non-encapsulated thermochromic liquid crystals (TLC) particles, to measure the volumetric 3D velocity-and temperature field in an evaporating droplet with a measurement volume depth of 20 μm . Also, Massing et al (2016Massing et al ( , 2018 used luminescent polymer particles to measure the three-dimensional temperature and velocity field of a heated flow in a channel with a cross section of 2 × 2 mm 2 . Rossi et al (2019) investigated the phenomena of electrokinetically induced pattern formation and measured the particle concentration and velocity in a 350 × 30 μm 2 trapezoidal channel.…”

Section: Introductionmentioning

confidence: 99%

Utilizing the ball lens effect for astigmatism particle tracking velocimetry

et al. 2020

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In the present study, a simple method is developed to apply astigmatism particle tracking velocimetry (APTV) to transparent particles utilizing backlight illumination. Here, a particle acts as ball lens and bundles the light to a focal point, which is used to determine the particle's out-of-plane position. Due to the distance between focal point and particle, additional features have to be considered in ball lens astigmatism particle tracking velocimetry (BLAPTV) compared to conventional APTV. We describe required calibration steps and perform parameter studies to show how the autocorrelation coefficient and the light exposure affect the accuracy of the method. It is found that the accuracy and robustness of the Euclidean calibration approach as also used in conventional APTV (Cierpka et al. in Meas Sci Technol 22(1):015401, 2010a) can be increased if an additional calibration curve for the light intensity of the particle's focal point is considered. In addition, we study the influence of the particle diameter and the refractive index jump between liquid and particles on the calibration curves and the accuracy. In this way, particles of the same size, but different material, can be distinguished by their calibration curve. Furthermore, an approach is presented to account for shape changes of the calibration curve along the depth of the measurement volume. Overall, BLAPTV provides high out-of-plane particle reconstruction accuracies with respect to the particle diameter. In test cases, position uncertainties down to 1.8% of the particle diameter are achieved for particles of d p = 124 μm. The measurement technique is validated for a laminar flow in a straight rectangular channel with a cross-sectional area of 2.3 × 30 mm 2. Uncertainties of 0.75% for the in-plane and 2.29% for out-of-plane velocity with respect to the maximum streamwise velocity are achieved.

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Section: Introductionmentioning

confidence: 99%

Utilizing the ball lens effect for astigmatism particle tracking velocimetry

et al. 2020

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“…In recent decades, advances in microfabrication techniques have led to the development of a wide variety of microfluidic devices [ 1 , 2 , 3 ]. For many microfluidic applications, the knowledge of the temperature field is of high technical and scientific importance [ 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Microfluidics Temperature Compensating and Monitoring Based on Liquid Metal Heat Transfer

Meng

et al. 2022

Micromachines

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Microfluidic devices offer excellent heat transfer, enabling the biochemical reactions to be more efficient. However, the precision of temperature sensing and control of microfluids is limited by the size effect. Here in this work, the relationship between the microfluids and the glass substrate of a typical microfluidic device is investigated. With an intelligent structure design and liquid metal, we demonstrated that a millimeter-scale industrial temperature sensor could be utilized for temperature sensing of micro-scale fluids. We proposed a heat transfer model based on this design, where the local correlations between the macro-scale temperature sensor and the micro-scale fluids were investigated. As a demonstration, a set of temperature-sensitive nucleic acid amplification tests were taken to show the precision of temperature control for micro-scale reagents. Comparations of theoretical and experimental data further verify the effectiveness of our heat transfer model. With the presented compensation approach, the slight fluorescent intensity changes caused by isothermal amplification polymerase chain reaction (PCR) temperature could be distinguished. For instance, the probability distribution plots of fluorescent intensity are significant from each other, even if the amplification temperature has a difference of 1 °C. Thus, this method may serve as a universal approach for micro–macro interface sensing and is helpful beyond microfluidic applications.

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“…For the detailed analysis of many natural and technical systems, the simultaneous determination of several physical quantities is necessary. In many cases, simultaneous measurements of the velocity and temperature are of interest, as these quantities allow for investigations of the transport of momentum and heat, e.g., in natural convection (Schmeling et al 2014;Tummers and Steunebrink 2019), process engineering (Massing et al 2018) and general heat transfer problems (Cafiero et al 2014;Irwansyah et al 2016). For this purpose, many different measurement techniques with each having its own specific advantages and disadvantages have proven to be successful, enabling the choice of an appropriate measurement technique based on the application.…”

Section: Introductionmentioning

confidence: 99%

On the application of neural networks for temperature field measurements using thermochromic liquid crystals

2020

Self Cite

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This study presents an investigation regarding the applicability of neural networks for temperature measurements using thermochromic liquid crystals (TLCs) and discusses advantages as well as disadvantages of common calibration approaches. For the characterization of the measurement technique, the dependency of the color of the TLCs on the temperature as well as on the observation angle and, therefore, on the position within the field of view of a color camera is analyzed in detail. In order to consider the influence of the position within the field of view on the color, neural networks are applied for the calibration of the temperature measurements. In particular, the focus of this study is on analysis of the error of temperature measurement for different network configurations as well as training methods, yielding a mean absolute deviation and a mean standard deviation in the range of 0.1 K for instantaneous measurements. On the basis of a comparison of this standard deviation to that of two further calibration approaches, it is shown that neural networks are suited for temperature measurements via the color of TLCs. Finally, the applicability of this measurement technique is illustrated at an exemplary temperature measurement in a horizontal plane of a Rayleigh-Bénard cell with large aspect ratio, which clearly shows the emergence of convective flow patterns by means of the temperature field.

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A volumetric temperature and velocity measurement technique for microfluidics based on luminescence lifetime imaging

Cited by 33 publications

References 43 publications

Utilizing the ball lens effect for astigmatism particle tracking velocimetry

Utilizing the ball lens effect for astigmatism particle tracking velocimetry

Microfluidics Temperature Compensating and Monitoring Based on Liquid Metal Heat Transfer

On the application of neural networks for temperature field measurements using thermochromic liquid crystals

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