US-12623233-B2 - Method and fluidic microsystem for the dielectrophoretic manipulation of suspended particles

US12623233B2US 12623233 B2US12623233 B2US 12623233B2US-12623233-B2

Abstract

The invention relates to a method for operating a fluidic microsystem ( 100 ) for the dielectrophoretic manipulation of suspended particles ( 1 ) having a particle diameter in a suspension liquid ( 2 ), wherein the microsystem ( 100 ) comprises: —a channel ( 10 ) having a longitudinal direction; —an electrode device ( 20 ) having an electrode ( 21 ), the longitudinal extent of which deviates from the longitudinal direction of the channel ( 10 ) and which has individually controllable electrode segments ( 22 ) for producing dielectrophoretic forces which act on the particles ( 1 ), each electrode segment ( 22 ) having a deflection angle α, relative to the longitudinal direction of the channel ( 10 ), and a segment length (s i ), which determine a segment offset (D i ) perpendicular to the longitudinal direction of the channel ( 10 ); and —a control device ( 30 ). The method comprises: —producing a flow of the suspension liquid ( 2 ) with a flow velocity so that the particles ( 1 ) successively pass through an interaction region of the electrode ( 21 ), which interaction region is spanned by the electrode segments ( 22 ); and —activating the electrode segments ( 22 ) in order to deflect the particles ( 1 ) onto predetermined motion paths ( 4, 5 ), which are determined by a superposition of flow forces in the flow of the suspension liquid ( 2 ) and of the dielectrophoretic forces at the electrode segments ( 22 ). During the passage of each particle, each of the electrode segments ( 22 ) which are passed by the particle ( 1 ) is activated in a clocked manner for a predetermined activation duration, according to the desired motion path ( 4, 5 ), the activation duration of each electrode segment ( 22 ) being determined by the quotient of the segment length (s i ) of the electrode segment ( 22 ) and the flow velocity. The electrode segments ( 22 ) are dimensioned such that the segment offset (D i ) of each electrode segment ( 22 ) is less than the particle diameter. For the deflection of each particle ( 1 ), at least two successive electrode segments ( 22 ) cooperate.

Inventors

Michael Kirschbaum
Marten Tobias Gerling
Nieves GODINO AMADO

Assignees

FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E. V.

Dates

Publication Date: 20260512
Application Date: 20210730
Priority Date: 20200803

Claims (20)

1 . A method for operating a fluidic microsystem for dielectrophoretic manipulation of suspended particles having a predetermined particle diameter in a suspension liquid, wherein the fluidic microsystem comprises: a channel having a longitudinal direction, an electrode device having an elongate electrode, a longitudinal extension of which deviating from a longitudinal direction of the channel and which has electrode segments that are individually activatable for generating dielectrophoretic forces acting on the suspended particles, wherein each electrode segment has a deflection angle relative to the longitudinal direction of the channel and a segment length, which determine a segment offset transverse to the longitudinal direction of the channel, and a control device by way of which the electrode segments can be activated, wherein the method comprises the steps: generating a flow of the suspension liquid with a flow velocity in the channel, so that the suspended particles in succession pass an interaction region of the elongate electrode which is spanned by the electrode segments, activating the electrode segments in order to deflect the suspended particles in the channel onto predetermined movement paths which are determined by a superposition of flow forces in the flow of the suspension liquid and the dielectrophoretic forces generated at the electrode segments, wherein as each particle passes, each of the electrode segments which the particle passes in succession is activated in a clocked manner by the control device in dependence on a desired movement path in each case for a predetermined activation time, wherein the activation time of each electrode segment is determined by a quotient of the segment length of each electrode segment and the flow velocity, and the electrode segments are so dimensioned that the segment offset of each electrode segment is smaller than the particle diameter, and in each case at least two successive electrode segments cooperate for a deflection of each particle.
2 . The method according to claim 1 , wherein the segment length of each electrode segment is less than or equal to 10 times the particle diameter.
3 . The method according to claim 1 , wherein the segment length of each electrode segment is less than or equal to twice the particle diameter.
4 . The method according to claim 1 , wherein the deflection angle of each electrode segment is less than 10°.
5 . The method according to claim 1 , wherein the deflection angle of each electrode segment is less than 5°.
6 . The method according to claim 1 , further comprising the steps of position detection for determining at least one particle position of each particle, and activation of the electrode segments in dependence on the at least one particle position of each particle.
7 . The method according to claim 6 , wherein the position detection comprises monitoring of the interaction region of the electrode with a microscope device with which the electrode segments which each particle passes in succession are detected directly.
8 . The method according to claim 6 , wherein the position detection comprises observing of a monitoring region upstream of the interaction region of the electrode with a microscope device, wherein the monitoring region is spaced apart from each of the electrode segments by a predetermined channel length and the electrode segments which each particle passes in succession are determined from an observation time of each particle in the monitoring region, the predetermined channel length and the flow velocity.
9 . The method according to claim 1 , further comprising the step of detection of at least one particle property of each particle, wherein activation of the electrode segments takes place in dependence on the at least one particle property.
10 . The method according to claim 9 , wherein the channel is divided downstream of the interaction region of the electrode into multiple subchannels, and each of the suspended particles is moved into one of the subchannels by the activation of the electrode segments in dependence on the at least one particle property.
11 . The method according to claim 1 , wherein the flow velocity of the suspension liquid is set at a predefined constant value by a control loop.
12 . The method according to claim 1 , wherein a distribution of the particles is chosen such that multiple particles are located in the interaction region of the electrode, wherein, when averaged over time, not more than one of the particles is located at each electrode segment.
13 . A fluidic microsystem configured for dielectrophoretic manipulation of particles having a predetermined particle diameter in a suspension liquid, comprising: a channel having a longitudinal direction, an electrode device having an elongate electrode, a longitudinal extension of which deviating from the longitudinal direction of the channel and which has a plurality of individually activatable electrode segments for generating dielectrophoretic forces acting on the particles, wherein each electrode segment has a deflection angle relative to the longitudinal direction of the channel and a segment length, which determine a segment offset transverse to the longitudinal direction of the channel, and a control device by way of which the electrode segments can be activated, wherein the channel is configured to receive a flow of the suspension liquid with a flow velocity such that the suspended particles pass in succession through an interaction region of the electrode which is spanned by the electrode segments, wherein the control device is configured to activate the electrode segments in order to deflect the particles in the channel onto predetermined movement paths which are determined by a superposition of flow forces in the flow of the suspension liquid and the dielectrophoretic forces generated at the electrode segments, the control device is configured, as the particles pass, to activate in a clocked manner each of the electrode segments which one of the particles passes in succession in dependence on a desired movement path in each case for a predetermined activation time, wherein the activation time of each electrode segment is determined by a quotient of the segment length of each electrode segment and the flow velocity, the electrode segments are so dimensioned that the segment offset of each electrode segment is smaller than the particle diameter, and the control device is configured to activate the electrode segments so that in each case at least two successive electrode segments cooperate for a deflection of each particle.
14 . The fluidic microsystem according to claim 13 , wherein the segment length of each electrode segment is less than or equal to 10 times the particle diameter.
15 . The fluidic microsystem according to claim 13 , wherein the segment length of each electrode segment is less than or equal to 100 μm.
16 . The fluidic microsystem according to claim 13 , wherein the segment length of each electrode segment is less than or equal to 10 μm.
17 . The fluidic microsystem according to claim 13 , which comprises a position detection device with which at least one particle position of each particle can be detected, wherein the control device is configured to activate the electrode segments in dependence on the at least one particle position of each particle.
18 . The fluidic microsystem according to claim 17 , wherein the position detection device comprises a microscope device which is arranged to observe the interaction region of the electrode and to directly detect the electrode segments which each particle passes in succession.
19 . The fluidic microsystem according to claim 17 , wherein the position detection device comprises a microscope device which is arranged to observe an monitoring region upstream of the interaction region of the electrode with the microscope device, wherein the monitoring region is spaced apart from each of the electrode segments by a predetermined channel length, and the control device is configured to determine the electrode segments which each particle passes in succession from an observation time of each particle in the monitoring region, the predetermined channel length and the flow velocity.
20 . The fluidic microsystem according to claim 13 , wherein the control device is configured to activate the electrode in dependence on at least one particle property.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. National Phase Application of PCT/EP2021/071433, filed Jul. 30, 2021, which claims priority to DE 10 2020 120 425.6, filed Aug. 3, 2020, the contents of which applications are incorporated herein by reference in their entireties for all purposes. BACKGROUND OF THE INVENTION The invention relates to a method for the dielectrophoretic manipulation of suspended particles, in particular for sorting of suspended particles, such as, for example, biological cells or microcompartments, in a fluidic microsystem. The invention relates further to a fluidic microsystem which is adapted for the dielectrophoretic manipulation, in particular for the sorting, of suspended particles. Applications of the invention are, for example, in the processing of particles, in particular of biological cells, microcompartments or other microobjects, in chemistry, medicine, biology or biochemistry. In the present description, reference is made to the following prior art, which illustrates the technical background of the invention: [1] M. Boutros et al. (2015): Microscopy-based high-content screening. Cell 163, 1314-1325;[2] N. Godino et al. (2019): Combining dielectrophoresis and computer vision for precise and fully automated single-cell handling and analysis. Lab Chip 19, 4016-4020;[3] C.-T. Ho et al. (2005): Micromachined electrochemical T-switches for cell sorting applications. Lab Chip 5, 1248-1258;[4] M. Kirschbaum et al. (2008): T cell activation on a single-cell level in dielectrophoresis-based microfluidic devices. J Chromatogr A. 1202 (1), 83-89;[5] B. Landenberger et al. (2012): Microfluidic sorting of arbitrary cells with dynamic optical tweezers. Lab Chip 12, 3177-3183;[6] M. Li et al. (2018): Cellular dielectrophoresis coupled with single-cell analysis. Analytical and Bioanalytical Chemistry 410, 2499-2515;[7] G. Meineke et al. (2016): A microfluidic opto-caloric switch for sorting of particles by using 3D-hydrodynamic focusing based on SLE fabrication capabilities. Lab Chip 16, 820-828;[8] N. Nitta et al. (2018): Intelligent Image-Activated Cell Sorting. Cell 175(1):266-276;[9] S. Sakuma et al. (2017): On-chip cell sorting by high-speed local-flow control using dual membrane pumps. Lab Chip 17, 2760-2767;[10] Y. Shen et al. (2019): Recent advances in microfluidic cell sorting systems. Sensors & Actuators: B. Chemical 282, 268-281;[11] DE 198 15 882 A1;[12] DE 198 60 117 A1; and[13] DE 198 60 118 C1. In biology and medicine, there is a strong interest in the characterisation and processing of heterogeneous particle samples, such as, for example, heterogeneous cell samples. It is generally known that conventional flow cytometry allows large cell samples to be characterised within a short time on the basis of very simple markers (“low-content” markers), such as, for example, the size, granularity or integral fluorescence intensity of the biological cells. In order also to detect structural properties of individual cells or synthetic microcompartments in a spatially resolved manner (“high-content” markers), microscopy techniques are typically used. The “high-content” markers are highly relevant for modern biomedicine because biological processes, for example, are often determined by the spatial arrangement of cell constituents [1]. Thus, important cell properties, such as, for example, the antigen specificity of immune cells, coagulation disorders of blood platelets or the metastasisation potential of cancer stem cells, manifest themselves via the strength and nature of the interaction of cells with one another, the local protein distribution within the cell and/or via the number and arrangement of cellular constituents. For functional analyses, it is important not only to be able to identify the cells on the basis of their phenotype but also to be able to sort them, which is possible on the basis of flow cytometry using the fluorescence-activated cell sorting (FACS) technique. However, it has hitherto not been possible to combine available FACS devices with microscopy techniques, and for that reason only “low-content” markers and not “high-content” markers can be detected. Owing to the complexity of biological processes, the FACS technique is therefore not suitable for many questions of biomedicine for sufficiently distinguishing individual cell types or subpopulations from one another. Combination with a microscopy technique is possible for many fluidic microsystems with planar channel structures. By means of such systems, microscope image data from microscopy techniques or measured data from other complex measuring techniques can thus be used directly for the identification and sorting of cells on the basis of “high-content” markers. The sorting of suspended cells moving one behind the other in a channel of a fluidic microsystem can be carried out with micromechanical ([3]), optical ([5]), hydrodynamic ([7], [8] or [9]), electrokinetic ([2]) or other ([10])