High-current density DC magenetohydrodynamics micropump with bubble isolation and release system

345

169

Micro-magnetofluidics refers to the science and technology that combines magnetism with microfluidics to gain new functionalities. Magnetism has been used for actuation, manipulation and detection in microfluidics. In turn, microfluidic phenomena can be used for making tunable magnetic devices. This paper presents a systematic review on the interactions between magnetism and fluid flow on the microscale. The review rather focuses on physical and engineering aspects of micro-magnetofluidics, than on the biological applications which have been addressed in a number of previous excellent reviews. The field of micromagnetofluidics can be categorized according to the type of the working fluids and the associated microscale phenomena of established research fields such as magnetohydrodynamics, ferrohydrodynamics, magnetorheology and magnetophoresis. Furthermore, similar to microfluidics the field can also be categorized as continuous and digital micro-magnetofluidics. Starting with the analysis of possible magnetic forces in microscale and the impact of miniaturization on these forces, the paper revisits the use of magnetism for controlling fluidic functions such as pumping, mixing, magnetowetting as well as magnetic manipulation of particles. Based on the observations made with the state of the art of the field micro-magnetofluidics, the paper presents some perspectives on the possible future development of this field. While the use of magnetism in microfluidics is relatively established, possible new phenomena and applications can be explored by utilizing flow of magnetic and electrically conducting fluids.

Section: Electrically Conducting Fluidsmentioning

confidence: 96%

Micro-magnetofluidics: interactions between magnetism and fluid flow on the microscale

Nguyen

2011

345

169

“…Electrohydrodynamic (Ehlert et al 2008), magnetohydrodynamic (Nguyen and Kassegne, 2008), electroosmotic (Wu et al 2005;Lee and Li 2006;Hu et al 2007b;Park and Lim 2008), and electrowetting (Mugele and Baret 2005) micropumps fall into this category. These types of dynamics micropumps have been extensively investigated and reviewed by many researchers (Iverson and Garimella 2008).…”

Section: Dynamic Micropumpsmentioning

confidence: 97%

Steady and unsteady flow analysis in microdiffusers and micropumps: a critical review

Nabavi

2009

In recent research, there has been a growing interest in the analysis of flow through microdiffusers and micropumps in order to characterize and optimize the performance of these devices. In this review, the recent advances in the numerical and experimental analysis of the steady and pulsating flows through microdiffusers and valveless micropumps are surveyed. The differences between the performance of microdiffusers and micropumps in steady and unsteady flow regimes are described. Qualitative and quantitative discussions of the effects of different design parameters on the performance of microdiffusers and valveless micropumps in both steady and unsteady flow regimes along with the contradictory results reported in the literature in this regard are provided. In addition, a summary of the latest micropump technologies along with the advantages and disadvantages of each mechanism with the emphasis on the innovative and lessreviewed micropumps are presented. Two important types of fixed microvalves, as part of valveless micropumps are described in details. Experimental flow visualization of steady and pulsating flows through microdiffusers and micropumps as a useful tool for better understanding the underlying micro-fluid dynamics is discussed. The present review reveals that there are many possible areas of research in the field of steady and unsteady flows through microdiffusers and micropumps in order to understand the effects of all important design parameters on the performance of these devices. List of symbols uVelocity in x direction (m/s) v Velocity in y direction (m/s) u max Maximum velocity in x direction (m/s) Q Volumetric flow rate (m 3 /s) Q net Net flow rate (m 3 /s) q Density (kg/m 3 ) p Pressure (Pa) p 0 Static pressure (Pa) t Time (s) x Axial position (m) y Transverse position (m) T Excitation period (s) l Shear viscosity (kg/m s) m Kinematic viscosity (m 2 /s) Re = u max D h /m Reynolds number St = x D h /u max Strouhal number Ro = x D h 2 /m = Re.St Roshko number Wo = D h /d Womersley number V Volume-average velocity (m/s) P Maximum pressure (Pa) Dp Frictional pressure drop (Pa) g Diffuser efficiency g max Maximum diffuser efficiency n d Total pressure loss coefficient in the diffuser direction n n Total pressure loss coefficient in the nozzle direction

“…Micropumps may be divided into two categories according to the way fluid is displaced. Hydrodynamic micropumps such as elctrohydrodynamic (Ehlert et al 2008), magnetohydrodynamic (Nguyen and Kassegne 2008) and electroosmotic (Wu et al 2005;Park and Lim 2008) micropumps involve a continuous energy source that produces a steady force on the fluid. Positive displacement micropumps add energy periodically by applying a force to one or more movable pump chamber walls.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of high frequency pulsating flows through a diffuser-nozzle element in valveless acoustic micropumps

Nabavi

Mongeau

2009

The concept of a valveless acoustic micropump was investigated. Two-dimensional, time-varying, axisymmetric, incompressible viscous flows through a planar diffuser-nozzle element were analyzed for applications in valveless acoustic micropumps. The diffuser divergence half-angles (h), and the maximum pressure amplitudes (P) were independently varied. The inflow was periodic and the excitation frequency (f) was varied over the range 10 kHz B f B 30 kHz. The net time-averaged volume flux and the rectification capability of the diffuser were found as functions of h, f, and P. The phase difference between pressure and velocity waveforms, the life time and the size of large scale flow recirculation regions inside the microdiffuser, and energy losses were found to be strongly frequency dependent. Keywords Acoustic micropumps Á Acoustic standing waves Á Microdiffuser Á Numerical analysis List of symbols DP Pressure drop (Pa) d Stokes layer thickness (m) g Rectification capability k Acoustic wavelength (m) l Shear viscosity (kg/m s) m Kinematic viscosity (m 2 /s) x Angular frequency (rad/s) q Density (kg/m 3 ) h Diffuser divergence half-angle (°) n d Pressure loss coefficient in the diffuser direction n n Pressure loss coefficient in the nozzle direction D h Hydraulic diameter of the microdiffuser at the inlet (m) f Excitation frequency (Hz) I Flow inductance (kg/m 4 ) I d Flow inductance in the diffuser direction (kg/m 4 ) I n Flow inductance in the nozzle direction (kg/m 4 ) N Cell numbers P Maximum pressure (Pa) p Pressure (Pa) p 0 Static pressure (Pa) Q Volumetric flow rate (m 3 /s) Q net Net flow rate (m 3 /s) R Flow resistance (kg/m 4 s) R d Flow resistance in the diffuser direction (kg/m 4 s) R n Flow resistance in the nozzle direction (kg/m 4 s) Re Reynolds number T Excitation period (s) t Time (s) U Maximum velocity (m/s) u Velocity in x direction (m/s) v Velocity in y direction (m/s) V net Sectional net velocities (m/s) Wo Womersley number x Axial position (m) x max Maximum fluid displacement during one oscillation cycle (m) y Transverse position (m) Z Flow impedance (kg/m 4 s) Z d Flow impedance in the diffuser direction (kg/m 4 s) Z n Flow impedance in the nozzle direction (kg/m 4 s)