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Bató Lilia
An obstacle-free microfluidic system for monitoring protein diffusion

Aug 30 - szerda

11:00 – 11:15

Bioszenzorika és bio-nanotechnológia

E26

An obstacle-free microfluidic system for monitoring protein diffusion

Lilia Bató^1,2, Péter Fürjes¹

¹ Microsystems Lab., Inst. of Technical Physics and Materials Science, Centre for Energy Research, ELKH, Budapest, Hungary

² Óbuda University Doctoral School on Materials Sciences and Technologies, Budapest, Hungary

Determining characteristic chemical and physical properties of proteins are essential for predicting their behaviour and interactions in Lab-on-Chip and Organ-on-Chip systems. Diffusion coefficients are widely used to estimate molecule size, hydration state or aggregation [1, 2]. Constructed diffusion is crucial to develop adequate molecular concentration distribution in these applications. Our goal is to develop a free-diffusion based obstacle-free microfluidic device to achieve fast diffusion coefficient measurements.

A specific microfluidic system was created – inspired by Taylor et al. [3] – containing two main channels connected by multiple perpendicular capillaries to ensure stable and stationary molecular concentration at the edge of the monitoring channel. The device was fabricated by soft lithography in polydimethylsiloxane and was bonded to a glass slide. The main channels were filled with test puffer and adequate fluorescent protein solutions, respectively. The symmetry of the layout minimizes the pressure differences between the channels.

Diffusion coefficient of various, fluorescently labelled proteins (bovine serum albumin, immunoglobulin G, rhodamine B) were determined using time dependent fluorescent microscopy. To acquire the evolving intensity profiles along the channels 30 s time-lapse images were taken. Python evaluation code was developed to fit model complementary error functions to the experimental profiles and calculate the diffusion coefficients. The defined diffusion coefficients for the certain proteins were in accordance with the values found in literature and estimated by the Stokes-Einstein equation.

Easy-to-use free-diffusion based microfluidic system were developed and proved to be applicable for fast determination the diffusion coefficients of characteristic proteins, using time-lapse fluorescent imaging and efficient evaluation algorithm.

Acknowledgement

The work was supported by the National Research, Development and Innovation Fund (NKFIA) via INBIOM TKP2021-EGA-04 grant.

References

• [1] P. Arosio et al, ACS Nano, 10: 333-341, 2015
• [2] M. R. G. Kopp and P. Arosio, J. Pharm. Sci, 107: 1228-1236, 2018
• [3] Taylor et al. Nat. Methods, 8:599-605, 2005

Szomor Zsombor
Finite element modelling and analysis of fluid dynamic phenomena in two-phase droplet based microfluidic systems

Aug 29 - kedd

15:30 – 17:00

I. Poszterszekció

P29

Finite element modelling and analysis of fluid dynamic phenomena in two-phase droplet based microfluidic systems

Zsombor Szomor^1,2, Eszter L. Tóth ¹, Péter Fürjes ¹

¹ Microsystems Lab., Inst. of Technical Physics and Materials Science, Centre for Energy Research, ELKH, Budapest, Hungary

² Óbuda University Doctoral School on Materials Sciences and Technologies, Budapest, Hungary

Recently the development and application of Lab-on-a-Chip and microfluidic devices have been spreading, enabling not only the extension of biological sample preparation and sensing solutions, but the comprehensive analysis and understanding of microscale fluid dynamic phenomena. The high performance finite element modelling (FEM) environments combined with experimental methods are enable solid description of microfluidic processes and reliable prediction the behaviours of novel architectures. However, the modelling of multiple-phase flows in microscale geometries is still a challenge.

Finite element Modelling code – COMSOL Multiphysics – was applied to analyse the process of droplet formation in 2D and 3D two-phase models to achieve more accurate comprehension of the behaviour of microfluidic systems depending on geometries and fluid parameters [1]. The analysis is based on the numerical solution of the governing Navier-Stokes and continuity equations. The fluidic environment and boundary conditions in these specific capillary systems can be characterised by the Capillary-number, which describes the relationship between the surface tension and the viscous forces. In this work the influence of channel geometries, the volume flow ratio at the inlets, the viscosity of the fluids, and the interface tension were studied in successive parametric sweep simulations. For handling multiphase fluids in 2D and 3D models a robust Level Set calculation method was used [2].

The droplet generation phenomena was studied by experimental methods, to verify FEM results, proving that the droplet formation processes as well as droplet sizes and generation frequencies are significantly affected accordingly can be effectively controlled by the geometric and flow parameters. The microfluidic systems were manufactured by soft lithography techniques in Polydimethylsiloxane (PDMS) polymer and tested using water / oil two phase fluid system.

Acknowledgement

The work was supported by the National Research, Development and Innovation Fund (NKFIA) via INBIOM TKP2021-EGA-04 grant.

References

• [1] K. J. Donovan. „Computational fluid dynamics modeling of two - dimensional and three - dimensional segmented flow in microfluidic chips”, San Jose State University, 2014. doi:10.31979/etd.3tzd-y6xm.
• [2] H. A. Akhlaghi Amiri, A. A. Hamouda, Evaluation of level set and phase field methods in modeling two phase flow with viscosity contrast through dual-permeability porous medium, International Journal of Multiphase Flow 52, 22-34, 2013