Investigation of the motion of magnetic nanoparticles in microfluidics with a micro domain model
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TECHNICAL PAPER
Investigation of the motion of magnetic nanoparticles in microfluidics with a micro domain model Pe´ter Pa´lovics1
•
Ma´rta Rencz1
Received: 18 December 2018 / Accepted: 19 October 2020 The Author(s) 2020
Abstract In this paper the magnetic nanoparticle (MNP) dynamics in a microfluidic device is investigated in the presence of an external magnetic field. The nanoparticles are used for enzyme-substrate reaction measurements, where the enzyme is immobilized to the surface of the nanoparticles. During the measurements the microreactors, called microchambers are filled up with the MNPs where the distribution of the nanoparticles significantly influences the results of the further reaction measurements. In this paper the procedure of the nanoparticle aggregation is investigated numerically in the microchamber in a micro domain simulation space. First the acting forces on the MNPs are examined from the different phenomena. An in-house numerical model is presented where the dynamics of several MNPs are simulated in the micro-size domain. This model is also embedded in the open source CFD software OpenFOAM. The theoretical calculations and the simulations show that the particle-particle interaction due to magnetization plays an important role during the aggregation procedure. The particles in the magnetic field cluster over the time into chains, which phenomenon is in good agreement with the literature. A theoretical model of the chain dynamics is also established, which is compared to the simulation results. The presented micro domain model was later used to improve an Eulerian-Eulerian based two-phase CFD model and solver, which is able to model the complete MNP aggregation procedure in the magnetic field in macroscopic domains. List of symbols General notation a; b dp B; H M mi kn ; kt Q v c_ l q
a : scalar, b : 3D vector bx ; by ; bz particle diameter [m] magnetic field [T],[A m1 ] magnetization [A m1 ] magnetic moment of particle i [A m2 ] normal and tangential stiffness [N m1 ] flow rate [m3 s1 ] velocity [m s1 ] strain rate [s1 ] dynamic viscosity [Pa s] density [kg m3 ]
& Pe´ter Pa´lovics [email protected] Ma´rta Rencz [email protected] 1
Department of Electron Devices, Budapest University of Technology and Economics, Magyar tudo´sok krt. 2, Bld. Q, Budapest 1117, Hungary
v MNP CFD
magnetic susceptibility magnetic nanoparticle computational fluid dynamics
1 Introduction Magnetic nanoparticles are widely used in biomedical applications, such as in drug delivery, hyperthermia treatment or chemotherapy (Mohammed et al. 2017). MNPs are also used in enzyme-substrate reactions by immobilizing the enzyme to the nanoparticle surface. This technique offers re-usability of the enzyme, low cost and potential increase in thermal and pH stability (Ansari and Husain 2012). Investigating the enzyme-substrate reactions in microreactors with MNPs offers additional benefits due to the reduced size. The microreactor size is usually betw
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