Determining Liquid Properties for Application in Microfluidic Devices
Liquids, between nano- to microlitres, have proprieties, such as surface tension, contact angle and refractive index, that play an important role in fluid dynamics and that are challenging to microfluidics engineers and scientists. This work displays a study of these proprieties for commonly used liquids in microfluidic devices, like ultrapure water, ethylene glycol and glycerol, in contact with plates of Topas and borosilicate glass, that are the materials of the microfluidics devices fabrication. For the study of these proprieties, the probes used were dimensional characterized by means of an interferometer and the determination of surface tension and contact angle (static and dynamic) by Wilhelmy plate method using a tensiometer. The refractive index of the tested liquids was also determined. This study also focuses on establishing metrological traceability and an uncertainty budget for each measurand as they are important tools for quality assessment of measurement results.
Indeed, these liquid proprieties are crucial for microfluidic flow properties such as resistivity and fouling, which are key performance parameters of microfluidic devices. A contribution with measurement results of challenging liquid properties for use in microfluidic devices is given in this work.
João Lima is currently doing his thesis to obtain a master’s degree in Mechanical Engineering from the NOVA School of Science and Technology – Nova University of Lisbon – Portugal
Andreia Furtado has received a PhD in Materials Science in 2012 from the Faculty of Sciences and Technology – Nova University of Lisbon – Portugal. She is the head of Properties of Liquids Laboratory of Portuguese Institute for Quality (IPQ), where she works as a senior metrology scientist since 2006.
Elsa Batista holds a PhD in Mechanical Engineering from NOVA School of Science and Technology in 2022, a master’s degree in Analytical Chemistry from the University of Sciences in Lisbon in 2007 and has a degree in Applied Chemistry from the NOVA School of Science and Technology in 1999. Since 1999, she has worked at the Laboratório de Volume of Instituto Português da Qualidade as a superior technician and laboratory manager. She is the contact person and head of the volume subgroup of the EURAMET flow technical committee.
Sara Moura has received a postgraduate degree in Management in Quality and Food Safety in 2004 from the Higher Institute of Health Sciences – South; Egas Moniz C.R.L. – Portugal. She is senior technician in Properties of Liquids Laboratory of Portuguese Institute for Quality (IPQ), where she works since 2021. Her research interests are in the areas of density, viscosity, surface tension and reology.
Helena Navas has received a PhD from NOVA School of Science and Technology – Universidade NOVA de Lisboa – Portugal. She is currently Assistant Professor at the Department of Mechanical and Industrial Engineering of the NOVA School of Science and Technology – Portugal and researcher at UNIDEMI. Her research interests are in the areas of innovation, continuous improvement, quality, and process management.
Olivier Pellegrino has received a PhD in Physics in 1995 from the Pierre et Marie Curie University of Paris VI – France. He is the head of Photometry and Radiometry Laboratory of Portuguese Institute for Quality (IPQ) where he has worked as a senior metrology scientist since 2002.
[1] Kirby BJ (2010). Micro- and Nanoscale Fluid Mechanics: Transport in Microfluidic Devices. NY, USA: Cambridge University Press.
[2] Morrison, S. Roy, (Ed.). (1990). The chemical physics of surfaces (2nd ed.). Springer
[3] van Heeren, H. (2022, October 10). Whitepaper on the measurement of hydrophobicity, hydrophilicity, and wettability; Version: 1.0; Retrieved from; https://zenodo.org/record/7181091#.Y0b4WHbMJPY
[4] Batista, E., Sousa, J. A., Cardoso, S. & Silvério, V. (2020). Experimental testing for metrological traceability and accuracy of liquid microflows and microfluidics. Flow Measurement and Instrumentation, 71, 101691.
[5] Batista, E., Sousa, J. A., Alvares, M., Afonso, J. & Martins, R., (2021), Development of an experimental setup for micro flow measurement using the front tracking method. Measurement: Sensors, 18, 100152
[6] www.mfmet.eu
[7] Singh, S. (2002), Refractive Index Measurement and its Applications. Physica Scripta, 65(2), 167-180. DOI: 10.1238/physica.regular.065a0
[8] ISO 3696:1987 (1987) Water for analytical laboratory use – Specification and test methods
[9] Taylor & Francis Group (2023) Handbook of Chemistry and Physics (104th Ed.), CRC Press,
[10] Krüss Scientific. Retrieved from https://www.kruss-scientific.com/en/products-services/accessories/pl21
[11] Topas plates provided by Microfluidic ChipShop. Retrieved from Topas – COC – microfluidic ChipShop (microfluidic-chipshop.com)
[12] Glass plates commercially available from WillCo Wells. Retrieved from Specifications-glass-D-263-M.pdf (willcowells.com)
[13] ISO 304:1985 (reviewed in 2019); Surface active agents – Determination of surface tension by drawing up liquid films and Technical Corrigendum (1998)
[14] Krüss User Manual V3.2.2-11 Laboratory Desktop Software
[15] Picard, A., Davis, R. S., Gläser, M., & Fujii, K. (2008). Revised formula for the density of moist air (CIPM-2007). Metrologia, 45(2), 149.
[16] Purr, F., Bassu, M., Lowe, R. D., Thürmann, B., Dietzel, A., & Burg, T. P. (2017). Asymmetric nanofluidic grating detector for differential refractive index measurement and biosensing. Lab on a Chip, 17(24), 4265–4272. DOI:10.1039/c7lc00929a
[17] JCGM 100:2008 (2008) Evaluation of measurement data – Guide to the expression of uncertainty in measurement. BIPM.
[18] Lima, J. M. V. (2023). Development and validation of methods for determination of liquid properties, volume and flow in microfluidic devices (Dissertação de Mestrado não publicada). Universidade Nova de Lisboa, Monte da Caparica.
[19] ISO 19403-2 (2017) Paints and varnishes — Wettability — Part 2: Determination of the surface free energy of solid surfaces by measuring the contact angle
[20] JCGM 200 (2012), International Vocabulary of Metrology – Basic and General Concepts and Associated Terms. VIM 3rd edition. BIPM.
[21] Spieweck, F. & Bettin, H. (1992) Review: Solid and liquid density determination. Technisches Messen 59, pp. 285-292
Contact angle, microfluidics, surface tension, refractive index
