A new micro pump for rapid and accurate microscale droplet manipulation using thermo-viscous actuation

Document Type : Article


1 Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran

2 - Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran - Aerospace and Energy Conversion Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Iran


Current study proposes a novel mechanism for micro scale droplet generation. To this end, a new micro pump consisting of an expansion chamber with two nozzles at its left and right sides, is introduced which is capable of creating a unidirectional flow. In the current study, for the first time, thermo-Viscose expansion method is used to actuate the flow by assuming that the fluid is heated by using a laser beam source leading to expansion and movement of the fluid. Two-phase flow analysis using the VOF method showed that the proposed micro pump can consistently generate droplets with uniform and micro-scale dimensions.


1. Huang, J., Segura L.J., Wang T., et al. "Unsupervised learning for the droplet evolution prediction and process dynamics understanding in inkjet printing", Additive Manufacturing, 35, p. 101197 (2020).
2. Cech, J., Schrott, W., Slouka, Z., et al. "Enzyme hydrolysis of soybean oil in a slug  flow microsystem", Biochemical Engineering Journal, 67, pp. 194-202 (2012).
3. Kaminski, T.S., Scheler, O., and Garstecki, P. "Droplet micro fluidics for microbiology: Techniques, applications and  hallenges", Lab Chip, 16, pp. 2168- 2187 (2016).
4. Papadimitriou, V.A., Kruit, S.A., Segerink, L.I., et al. "Droplet encapsulation of electrokinetically-focused analytes without loss of resolution", Lab Chip, 20, pp. 2209-2217 (2020).
5. Barzegar Gerdroodbary, M., Ganji, D.D., Moradi, R., et al. "Application of Knudsen thermal force for detection of CO2 in low-pressure micro gas sensor", Fluid Dynamics, 53, pp. 812-823 (2018).
6. Mozaffari, M., D'Orazio, A., Karimipour, A., et al. "Lattice Boltzmann method to simulate convection heat transfer in a microchannel under heat flux: Gravity and inclination angle on slip-velocity", Int. J. Numerical Methods for Heat &Fluid Flow, 30(6), pp. 3371-3398 (2020).
7. Dmitry, S.G. and Gatapova, E.Y. "Friction reduction by inlet temperature variation in microchannel  flow", Physics of Fluids, 33, p. 062003 (2021).
8. Wang, F., Wang, Y., Bao, W., et al. "Controlling ejection state of a pneumatic micro-droplet generator through machine vision methods", Int. J. Precis. Eng. Manuf., 21, pp. 633-640 (2020).
9. He, Z., Wang, J., Fike, B.J., et al. "A portable droplet generation system for ultra-wide dynamic range digital PCR based on a vibrating sharp-tip capillary", Biosensors and Bioelectronics, 191, p. 113458 (2021).
10. Rayleigh, J.W.S. "On the instability of jets", Proc. Lond Math. Soc., 10, pp. 4-13 (1878).
11. Kalantarifard, A., Alizadeh-Haghighi, E., Elbuken, C., et al. "Theoretical and experimental limits of monodisperse droplet generation", Chemical Engineering Science, 229, 116093 (2021).
12. Hoseinpour, B. and Sarreshtehdari, A. "Lattice Boltzmann simulation of droplets manipulation generated in lab-on-chip (LOC) micro fluidic T-junction", J. Molecular Liquids, 297, p. 111736 (2020).
13. Teo, A.J.T., Yan, M., Dong, J., et al. "Controllable droplet generation at a micro fluidic T-junction using AC electric field", Micro fluidics and Nanofluidics, 24(3), pp. 1-9 (2020).
14. Tan, Y.C., Cristini, V., and Lee, A.P. "Monodispersed micro fluidic droplet generation by shear focusing micro fluidic device", Sensors and Actuators B: Chemical, 114(1), pp. 350-356 (2006).
15. Besanjideh, M., Shamloo, A., and Kazemzadeh Hannani, S. "Enhanced oil-in-water droplet generation in a T-junction microchannel using water-based nanofluids with shear-thinning behavior: A numerical study", Physics of Fluids, 33, p. 012007 (2021).
16. Bao, W., Wang, Y., Yang, B., et al. "Some considerations for designing a pneumatic micro-droplet generator", J. Micromech. Microeng., 31, p. 045008 (2021).
17. Wang, F., Wang, Y., Bao, W., et al. "Controlling ejection state of a pneumatic micro-droplet generator through machine vision methods", Int. J. Precis. Eng. Manuf., 21, pp. 633-640 (2020).
18. Guo, Q., Su, X., Zhang, X., et al. "A review on acoustic droplet ejection technology and system", Soft Matter, 17, pp. 3010-3021 (2021).
19. Li, H., Liu, J., Liu, Y., et al. "Development of a resonant piezoelectric micro-jet for high-viscosity liquid using a longitudinal transducer", Mechanical Systems and Signal Processing, 146, p. 107012 (2021).
20. Xuan, L.P., Quang, L.D., Quoc, T.V., et al. "Development of a micro fluidic flow-focusing droplet generating device utilising rapid prototyping technique", Int. J. Nanotechnology, 17, pp. 708-721 (2020). 
21. Madou, M., Zoval, J., Jia, G., et al. "Lab on a CD", Annu. Rev. Biomed. Eng., 8, pp. 601-628 (2006).
22. Saint Vincent, M.R., Chraibi, H., and Delville, J.P. "Optical flow focusing: Light-induced destabilization of stable liquid threads", Phys. Rev. Appl., 4, p. 044005 (2015).
23. Kazuno, N., Tsukahara, T., and Motosuke, M. "Laplace pressure versus Marangoni convection in photothermal manipulation of micro droplet", Eur. Phys. J. Special Topics, 226, pp. 1337-1348 (2017).
24. Zhu, P. and Wang, L. "Passive and active droplet generation with microfluidics: a review", Lab Chip, 17, pp. 34-75 (2017).
25. Cetin, B., Bulent  Ozer, M., and Ertugrul Solmaz, M., et al. "Micro fluidic bio-particle manipulation for biotechnology", Biochemical Engineering Journal, 92, pp. 63-82 (2014).
26. Yariv, E. and Brenner, H. "Flow animation by unsteady temperature fields", Physics of Fluids, 16(11), p. L95 (2004).
27. Pal, D. and Chakraborty, S. "Axial  flow in a twodimensional microchannel induced by a travelling temperature wave imposed at the bottom wall", J. Fluid Mech., 848, pp. 1040-1072 (2018).
28. Pal, D. and Chakraborty, S. "Fluid  flow induced by periodic temperature oscillation over a at plate", Physics of Fluids, 27(5), p. 053601 (2015).
29. Weinert, F.M., Kraus, J.A., Franosch, T., et al. "Microscale fluid flow induced by thermoviscous expansion along a traveling wave", Physical Review Letters, 100(16), p. 164501 (2008).
30. Weinert, F.M.,Wuhr, M., and Braun, D. "Light driven micro flow in ice", Applied Physics Letters, 94(11), p. 113901 (2009).
31. Weinert, F.M. and Braun, D. "Optically driven fluid flow along arbitrary microscale patterns using thermoviscous expansion", J. Applied Physics, 104(10), p. 104701 (2008).
32. Cui, W., Yesiloz, G., and Ren, C.L. "Numerical analysis on droplet mixing induced by microwave heating: Decoupling of in
uencing physical properties", Chemical Engineering Science, 224, p. 115791 (2020).
33. Xia, Z., Zhao, Y., Yang, Z., et al. "The simulation of droplet impact on the super-hydrophobic surface with micro-pillar arrays fabricated by laser irradiation and silanization processes", Colloids and Surfaces A: Physicochemical and Engineering Aspects, 612, p. 125966 (2021).
34. Zhu, L., Monteil, D.T., Wang, Y., et al. "Fluid dynamics of  flow fields in a disposable 600-mL orbitally shaken bioreactor", Biochemical Engineering Journal, 129, pp. 84-95 (2018).
35. Guan, H., Wang, J., Wei, Z., et al. "Numerical analysis of the interaction of 3D compressible bubble clusters", Appl. Math. Mech.-Engl. Ed., 40, pp. 1181-1196 (2019).