Microfluidics

The research project aims to characterize a 2D single cell analysis setup based on surface acoustic waves (SAW). For the first time, the position of the cells, the flow velocity of the surrounding fluid as well as the local temperature distribution will be investigated using novel, locally high-resolution measurement techniques to obtain detailed insights into the influence of high-frequency acoustic waves (>100 MHz) on fluids and the corpuscular components (particles, cells) suspended in them. By experimental characterizations of the SAW fields in the fluid-loaded microchamber by means of laser Doppler vibrometry and measurements of the velocity and temperature distribution with APTV, microacoustic, flow and thermodynamic issues will be specifically investigated and their dependencies highlighted. This will be supported by the development of models for the numerical simulation of local pressure and flow gradients. Based on the results, it should be possible in the future to derive design and application criteria for a 2D single-cell analysis arrangement that not only ensure stable operation of the arrangement but also promise low mechanical and thermal stress on the cells in endurance tests.

Funding Organisation: DFG

Partner:

Leibniz Institute for Solid State and Materials Research (IFW) Dresden

Researcher:

Prof. Dr.-Ing. Christian Cierpka (Project leader)
Dr.-Ing. Jörg König (Project leader)
Zhichao Deng (processor)

Publications:

Z. Deng, J. König, C. Cierpka (2022) A combined velocity and temperature measurement with an LED and a low-speed camera, Measurement Science and Technology 33. 115301 

R. Weser, Z. Deng, V. Kondalkar, S. Darinskii, H. Schmidt, C. Cierpka, J. König (2022) Three-dimensional heating and patterning dynamics of particles in microscale acoustic tweezers, Lab on a Chip 22, 2886-2901 

Z. Deng. V. Kondalkar, R. Weser, H. Schmidt, C. Cierpka, J. König: Experimental investigation of a SAW system for parallel analysis of single cells. Proceedings of the 28th GALA Symposium "Experimental Fluid Mechanics", September 7-9, 2021, Bremen, Germany, Editors: Fischer, A., Stöbener, D., Vanselow, C., Ruck, B., Leder, A., ISBN 978-3-9816764-7-1.

J. Massing, J. König, F. Kiebert, S. Wege, H. Schmidt, C. Cierpka: 3D3C velocity measurements using astigmatism particle tracking velocimetry (APTV) in SAW-based microfluidic mixers, Symposium "Lasermethoden in der Strömungsmesstechnik, 08.-10.09.2015, Dresden, Germany.

F. Kiebert, J. König, J. Massing, C. Cierpka, H. Schmidt (2017) 3D measurement and simulation of surface acoustic wave driven fluid motion: a comparison, Lab on a Chip 17, 2104-2114.
 

For many industrial applications, in process engineering and food chemistry as well as in pharmaceutical production, particle systems are of great importance. Through active methods using magnetic, electric and acoustic fields, promising systems have been developed that allow targeted fractionation of particle solutions in a flexible and easily scalable environment. The goal of this research project is to build a system that uses surface acoustic waves (SAW) to sort particles according to their size, shape, and acoustic contrast (mechanical properties). To characterize this system, astigmatism PTV will be used in conjunction with deep learning neural networks to measure acoustically excited flows and the three-dimensional particle positions while classifying particles according to their size and shape.

Funding source: DFG

Partners: 

Research groups within SPP 2045, TU Munich, DTU Copenhagen.

Workers:

Prof. Dr.-Ing. Christian Cierpka (Project leader)

Dr. Jörg König (project leader)

Sebastian Sachs (processor)

Publications:

S. Sachs, C. Cierpka, J. König (2022) On the acoustically induced fluid flow in particle separation systems employing standing surface acoustic waves – Part II, Lab on a Chip 22, 2028-2040 

S. Sachs, M. Baloochi, C. Cierpka, J. König (2022) On the acoustically induced fluid flow in particle separation systems employing standing surface acoustic waves – Part I, Lab on a Chip 22, 2011-2027 

R. Barnkob, C. Cierpka, M. Chen, S. Sachs, P. Mäder, M. Rossi (2021) Defocus particle tracking: a comparison of methods based on model functions, cross-correlation, and neural networks, Measurement Science and Technology 32, 094011

S. Sachs, C. Cierpka, J. König, 3D3C flow measurements of the acoustically induced vortex structures in a standing surface acoustic wave field. In: Proceedings of the Acoustofluidics 2021 conference, August 26-27, 2021, virtual conference.

S. Sachs, C. Cierpka, C, J. König, 3D3C flow measurements on the influence of acoustically induced vortex structures on particle fractionation in microchannels. Proceedings of the 28th GALA Symposium "Experimental Fluid Mechanics", September 7-9, 2021, Bremen, Germany, Editors: Fischer, A., Stöbener, D., Vanselow, C., Ruck, B., Leder, A., ISBN 978-3-9816764-7-1.

S. Sachs, C. Cierpka, J. König, Measurement of the acoustic streaming pattern in a standing surface acoustic wave field. In: Proceedings of the 14th International Symposium on Particle Image Velocimetry, August 1-4, 2021, virtual conference.

In microfluidic reactors and heat exchangers, it is often necessary to simultaneously measure the three-dimensional flow and temperature field with time resolution in order to draw conclusions about the fundamental physical phenomena. In astigmatism PTV, velocity determination is based on three-dimensional tracking of particles in the measurement volume. The basic principle is the encoding of the depth position of the particles via optical distortions by an additional cylindrical lens in the observation optics. If particles loaded with a temperature-sensitive dye are used for the measurement, the fluorescence signal can additionally be used to determine the temperature. Therefore, the goal in this research project is to improve the signal-to-noise ratio of the measurement technique and use it for microfluidic heat exchangers with nanofluids and other complex microfluidic devices.

Partner:

Bundeswehr University Munich

Researcher:

Prof. Dr.-Ing. Christian Cierpka (Project leader)
Dr. Jörg König (project leader)
Zhichao Deng (processor)

Publications:

Z. Deng, J. König, C. Cierpka (2022) A combined velocity and temperature measurement with an LED and a low-speed camera, Measurement Science and Technology 33. 115301 

J. Massing, N. van der Schoot, C. J. Kähler, C. Cierpka (2019) A fast start up system for microfluidic direct methanol fuel cells, International Journal of Hydrogen Energy 44, 26517-26529, DOI: 10.1016/j.ijhydene.2019.08.107

J. Massing, C.J. Kähler, C. Cierpka (2018) A volumetric temperature and velocity measurement technique for microfluidics based on luminescence lifetime imaging, Experiments in Fluids 59, 163.

X. Yang, D. Baczyzmalski, C. Cierpka, G. Mutschke, K. Eckert (2018) Marangoni convection at electrogenerated hydrogen bubbles, Physical Chemistry Chemical Physics 20, 11542.

J. Massing, D. Kaden, C.J. Kähler, C. Cierpka (2016) Luminescent two-color tracer particles for simultaneous velocity and temperature measurements in microfluidics, Measurement Science and Technology 27, 1153014.

R. Segura, M. Rossi, C. Cierpka, C.J. Kähler (2015) Simultaneous three-dimensional temperature and velocity field measurements using astigmatic imaging of non-encapsulated thermo-liquid crystal (TLC) particles. Lab on a Chip 15, 660-663

The magnetohydrodynamic conversion of kinetic energy of fluids into electric energy is well known and applied for power generation. A recent experiment shows a similarity between the magnetic field and the spin-orbit orientation in liquid metals, which opens a completely undiscovered path for energy conversion. This promising technique, known as spin hydrodynamic generation, relies on a coupling between the flow vorticity and electron spins to generate electricity with no needs of any external magnetic field. The spin hydrodynamic generation, however, is in its early infancy stage and many unresolved questions need to be addressed to enhance our understanding of how the macroscopic hydrodynamic world couples with the spin-orbitals on atomistic levels. In this regard, an experimental setup consisting of a large box to control the environmental conditions, a pressure vessel which is filled with the eutectic alloy Indium-Gallium-Tin (GaInSn), and connecting circular and non-circular capillary tubes was built. When a pressure (up to 10 bar) is applied the liquid metal is pushed through the capillary into another storage vessel placed on a high precision scale to determine the mass flow rate. The electrical potential is then measured between the electrodes at the beginning and at the end of the capillary. The primarily experimental results show a significant agreement with previous studies in the same range of the flow Reynolds number. For the extended range to lower and higher Reynolds numbers, measurements have provided compelling evidence for the validity of the proposed theories describing the generated electrical voltage via the spin-vorticity coupling.

Despite the first successful experiments, there is still a great need for a very good control of many parameters. Rigorous investigation of the concept could alter our perception of spintronics and our way of electric energy production completely.

Funding: Volkswagen Foundation                     

Partner:

• Prof. Dr. Jörg Schumacher

Project staff:

• Prof. Dr.-Ing. Christian Cierpka

• Dr. Hamid Tabaei Kazerooni

Publications:

H. Tabaei Kazerooni, A. Thieme, J. Schumacher, C. Cierpka (2020) Electron spin-vorticity coupling in low and high Reynolds number pipe flows, Physical Review Applied, accepted for publication (preprint on arxiv)