EP3391026A1

EP3391026A1 - Method for detecting particles in a sample, detection device, and microfluidic system for examining a sample

Info

Publication number: EP3391026A1
Application number: EP16825719.4A
Authority: EP
Inventors: Thomas BRETTSCHNEIDER; Jochen Hoffmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-12-18
Filing date: 2016-12-16
Publication date: 2018-10-24
Also published as: DE102015225849A1; WO2017103137A1; US20180372732A1

Abstract

The invention relates to a method for detecting particles (104) in a sample (102). The method has a step of reading a measurement signal (115) which represents at least one detected property of a magnetic field that extends from an interface (110) to at least one magnetic field sensor (130) at least through a sub-quantity of the sample (102). In the process, the sample (102) is provided with magnetic detection particles (106) which are designed to bond with the particles (104) to be detected. The method also has a step of ascertaining a fluctuation strength, which depends on the detection particles (106), of the at least one property of the magnetic field and a step of determining a bonding state of at least one detection particle (106) as unbonded or bonded to a particle (104) to be detected on the basis of the ascertained fluctuation strength in order to detect the particles (104) in the sample (102).

Description

Description title

Method for detecting particles in a sample, detection device and microfluidic system for assaying a sample

State of the art

The invention is based on a device or a method according to the preamble of the independent claims. The subject of the present invention is also a computer program.

It is known, for example, a diffusion constant of a particle under Brownian motion with the aid of an optical apparatus of the latter

To determine trajectory.

Disclosure of the invention

Against this background, with the approach presented here, a method, a device which uses this method, and finally a corresponding computer program according to the main claims are presented. The measures listed in the dependent claims are advantageous developments and improvements in the independent

Claim specified device possible.

According to embodiments of the present invention, particles to be detected in a sample can be detected in particular by magnetic detection of magnetic detection particles which can bind with the particles to be detected. In particular, a binding state of the detection particles can be detected, which can be related to a fluctuation of the detected magnetic field. Advantageously, according to embodiments of the present invention, in particular a process time or duration for the examination of samples or for the detection of particles can be shortened. Also, a qualitative and additionally or alternatively a quantitative detection of particles can be provided. Furthermore, for example, at least one detection particle needs to be added to a sample so that material costs can also be reduced. In addition, an integrability in so-called

Westentabelaborsysteme or lab-on-chip systems are simplified. According to embodiments of the present invention, it may also be possible to detect individual particles. Detection according to embodiments of the present invention may be conducted without contact and without optically transparent access to the sample. Furthermore, material selection among electrical dielectrics for such lab-on-chip systems can be increased.

A method for the detection of particles in a sample is presented, the method having the following features:

Reading in a measurement signal comprising at least one detected property of at least one subset of the sample

Magnetic field represents, from an interface to at least one

Magnetic field sensor, wherein the sample of magnetic detection particles are added, which are adapted to bind to the particles to be detected;

Determining a fluctuation intensity, dependent on the detection particles, of the at least one property of the magnetic field; and

Determining a binding state of at least one detection particle as unbound or bound to a particle to be detected as a function of the determined fluctuation strength to the particles in the sample

demonstrated.

This method can be used, for example, in software or hardware or in a mixed form of software and hardware, for example in a device or be implemented in a control unit. The sample may be a liquid sample or a sample in a liquid state. In this case, the sample can be arranged in a container and optionally stirred. In this case, the container may be formed as a vessel or a channel, wherein the sample can optionally be moved through the container. The

Fluctuation strength can be a fluctuation range of the measurement signal

represent.

Thus, it can be determined, for example with the aid of at least one magnetic field sensor, whether a magnetic particle is bound to a particle to be detected, in particular a biological particle such as a cell, without, for example, undergoing a complicated immunoassay workflow. A method of detecting particles in the form of cells may be used for microfluidic lab-on-chip medical diagnostic systems.

According to one embodiment, in the step of determining the

Binding state can be determined as unbound, if the fluctuation strength is in a first range of values. In this case, in the step of determining, the binding state can be determined as bound to a particle to be detected, if the fluctuation intensity lies in a second value range which represents lower fluctuation strengths than the first value range. The fluctuation strength of an unbound detection particle may be greater than the fluctuation strength of a detection particle bound to a particle to be detected. Such an embodiment offers the advantage that the

Binding state can be reliably determined and thus an accurate and reliable detection of a presence or absence of detected particles is made possible. Also, in the step of reading a measurement signal can be read, the one

Strength of the magnetic field and additionally or alternatively represents a direction of the magnetic field over time. Such an embodiment offers the advantage that an accuracy of a detection of the at least one

magnetic detection particle or one caused thereby

Magnetic field change can be increased. Further, the method may include a step of adding a predefined amount of the magnetic detection particles to the sample. Here, the detection particles may be contained in a liquid, solution or the like. Such an embodiment offers the advantage that a concentration of the detection particles in the sample can be accurately adjusted. Also in this case, for example, the concentration of the detection particles in the sample can be adjusted so that in each case a detection particle is in the region of the magnetic field sensor in order to increase a measurement accuracy.

In this case, in the step of adding detection particles can be added, which are adapted to antibody and additionally or alternatively to

To bind surface proteins of the particles to be detected. In this case, the particles to be detected can be biological particles. Additionally or alternatively, in the adding step, magnetic detection particles may be added to the sample. Thus, according to one embodiment, the

Detection particles have a magnetic portion and a binding portion, in particular an antibody portion or the like. Such an embodiment offers the advantage that, for example, cells or microorganisms can be detected specifically and reliably. In the case of paramagnetic detection particles, a

Detection accuracy can be further improved, in addition in particular a calibration of the at least one magnetic field sensor and the

Verification process allows or can be facilitated.

In addition, the method may include a step of generating the magnetic field. In this case, the measurement signal read in in the step of reading in may represent at least one property of the generated magnetic field. Such an embodiment offers the advantage that fluctuations of the generated magnetic field caused by the at least one detection particle can be reliably and accurately registered.

In this case, in the step of generating a homogeneous magnetic field than the

Magnetic field are generated. Additionally or alternatively, in the step of generating a magnetic field can be generated, which is designed to at least Immobilize detection particles adjacent to the at least one magnetic field sensor. Such an embodiment has the advantage that a rotation of the detection particles can be prevented by a homogeneous magnetic field and thus a detection accuracy can be increased, wherein by a magnetic holding the detection particles in a flowing sample a more accurate

Detection can be performed on individual detection particles. In addition, the immobilization may cause a detection particle relative to a

Magnetic field sensor can be positioned exactly.

Also, the method may include a step of circulating the sample with the added detection particles. In this case, the step of circulating before, during and additionally or alternatively after detecting the at least one property of the magnetic field can be executed. In this case, the sample can be circulated using a pump or a stirrer. In particular, the sample may be used between determining the

Binding state of a first detection particle and determining the binding state of a second detection particle are circulated.

Alternatively, the sample may be circulated continuously, with time intervals between determining the binding state different

Detection particles can be shortened and low-frequency signal components can be filtered out of the measurement signal. Such an embodiment offers the advantage that the binding state of detection particles

can be determined one after the other and additionally or alternatively one

Total duration of proof can be reduced.

There is also presented a detection device arranged to perform steps of an embodiment of the above method in respective units. The approach presented here thus also creates a detection device or

Device that is designed to perform the steps of a variant of a method presented here in corresponding facilities to drive or implement. Also by this embodiment of the invention in the form of a device, the object underlying the invention can be solved quickly and efficiently. For this purpose, the device may comprise at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading sensor signals from the sensor or for outputting data or control signals to the sensor Actuator and / or at least one

Communication interface for reading or outputting data embedded in a communication protocol. The arithmetic unit may be, for example, a signal processor, a microcontroller or the like, wherein the memory unit is a flash memory, an EPROM or a

magnetic storage unit can be. The communication interface can be designed to read or output data wirelessly and / or by line, wherein a communication interface that can read or output line-bound data, for example, electrically or optically read this data from a corresponding data transmission line or output in a corresponding data transmission line.

In the present case, a device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The device may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based embodiment, the interfaces can be part of a so-called system ASIC, for example, which contains a wide variety of functions of the device. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules. In an advantageous embodiment, by the detection device or

Device a control of at least one magnetic field sensor and additionally or alternatively at least a portion of a microfluidic system. For this purpose, the device can, for example, sensor signals such as

Access measurement signals. The device may be configured to respond to the measurement signal, to the determined fluctuation intensity and additionally or alternatively, to generate and provide or output at least one drive signal to the determined binding state. The activation takes place via actuators such as pumps, stirrers and additionally or alternatively devices for generating a magnetic field.

There is further provided a microfluidic system for assaying a sample, comprising: an embodiment of the above-mentioned detection device; and an interface for coupling to the at least one magnetic field sensor, wherein the measurement signal is transferable via the interface to the detection device. In connection with the microfluidic system, the detection device according to one embodiment mentioned above can advantageously be used to detect the particles when the sample is examined. The interface can be designed to produce a releasable mechanical and additionally or alternatively signal-transmissible connection between the microfluidic system and the at least one magnetic field sensor.

According to one embodiment, the microfluidic system may have a microfluidic channel in which the sample may be feasible. In this case, the detection device and additionally or alternatively the interface may be arranged adjacent to the microfluidic channel. In particular, the microfluidic system can be designed as a so-called west pocket laboratory (LoC, lab on chip, laboratory on a chip). Such an embodiment has the advantage that the examination of the sample with detection of the particles can be carried out inexpensively, space-saving and reproducible.

In this case, the interface may be designed to be the at least one

To arrange or move magnetic field sensor in contact with a wall of the microfluidic channel. Here, the wall of the microfluidic channel may be elastic, wherein the interface may be formed to the Wall of the microfluidic channel to deform by the at least one magnetic field sensor. Such an embodiment offers the advantage that a

Detection accuracy can be further increased because a distance between the sample and the at least one magnetic field sensor can be minimized.

Also, the microfluidic system may comprise at least one magnetic field sensor which may be removably coupled or coupleable to the interface. In this case, the at least one magnetic field sensor may, for example, be a one-dimensional magnetic field sensor or a three-dimensional one

Be executed magnetic field sensor. Such an embodiment offers the advantage that an accurate detection of particles on the one hand can be achieved by simple and inexpensive means by a one-dimensional sensor and on the other hand a security in the detection of the binding state by using a three-dimensional sensor can be further increased.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the above

described embodiments, in particular when the program product or program is executed on a computer or a device.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows:

1 shows a schematic representation of a microfluidic system according to an embodiment;

FIG. 2 is a flowchart of a method for detecting particles according to an embodiment; FIG.

Fig. 3 is a graph of magnetic field strengths versus time; 4 is a schematic sectional view of part of a microfluidic system according to an embodiment; and

Fig. 5 is a schematic sectional view of a part of a microfluidic system according to an embodiment.

In the following description of favorable embodiments of the present invention are for the in the various figures

represented and similar elements acting the same or similar

Reference is made to a repeated description of this

Elements is omitted.

First, principles for embodiments and background of the investigation of samples and the detection of particles will be explained. In analytical chemistry, for example, so-called bioassays are used to detect substances such as proteins, DNA molecules (DNA, deoxyribonucleic acid) or cells, for example pathogens, body cells or circulating

Tumor Cells (CTCs, Circulating Tumor Cells), e.g. B. for diagnostic purposes. For example, so-called immunoassays are frequently used to detect cells. In this case, detection antibodies are used which bind to a specific surface protein of a cell. To detect the cells bound by the detection antibodies, fluorescent probes or magnetic particles, so-called

Detection antibodies are used, which bind either to the detection antibody or to another surface protein of the cell. If the detection antibody immobilized on a surface, the detection antibodies and thus also the cells to be detected can be located and detected, it is a so-called sandwich immunoassay. Immunoassays are available in a variety of variations. For example, conventional immunoassays include a sequence of many substeps, e.g. B. adding sample,

Wash (remove excess), add detection antibody, wash, add detection antibody with probe, wash, proof. Such

Immunoassays can be expensive to carry out. The end result is information as to whether or not the probes (eg, magnetic particles) have bound to the cells to be detected. Furthermore, can optionally determine how many probes have bound to cells to allow for concentration determination.

1 shows a schematic representation of a microfluidic system 100 for examining a sample 102 according to an exemplary embodiment. The sample 102 contains particles 104 to be detected. Further, the sample 102

magnetic detection particles 106 added. The magnetic

Detection particles are designed to bind to the particles 104 to be detected or to enter into a chemical, physical or physicochemical bond with the particles 104 to be detected.

The microfluidic system 100 has an interface 110 and a

Detection device 120 on. The interface 110 is designed to enable a coupling with at least one magnetic field sensor 130. In other words, the interface 110 is coupled with at least one magnetic field sensor 130. The coupling between the interface 110 and the at least one magnetic field sensor 130 takes place here mechanically and / or signal transmission capability. Via the interface 110, a measurement signal 115 from a magnetic field sensor 130 coupled to the interface 110 can be transmitted to the detection device 120.

In the illustration of FIG. 1, a magnetic field sensor 130 is shown coupled to the interface 110. In this case, the magnetic field sensor 130 is detachably coupled to the interface 110. The magnetic field sensor 130 is configured to detect at least one property of a magnetic field that extends through at least a portion of the sample 102. The at least one property of the magnetic field is in this case in particular a strength and / or direction of the magnetic field over time. Further, the magnetic field sensor 130 is configured to provide or output the measurement signal 115. The measuring signal 115 represents the at least one detected characteristic of the magnetic field.

The detection device 120 is designed to detect the particles 104 to be detected or the particles 104 in the sample 102. For this purpose, the detection device 120 has a read-in device 121, a Detection device 122 and a determination device 123. The detection device 120 is designed to detect, in response to the measurement signal 115 and / or using the measurement signal 115, whether the particles 104 are present in the sample 102 or not.

The read-in device 121 of the detection device 120 is designed to read in the measurement signal 115 from the interface 110 to the magnetic field sensor 130. Furthermore, the read-in device 121 is designed to output the read measurement signal 115 to the determination device 122 or to provide it to the determination device 122. The read-in device 121 is connected to the detection device 122 in a signal-transmitting manner.

The determination device 122 is designed to use the measurement signal 115 to determine a fluctuation intensity of the at least one property of the magnetic field represented by the measurement signal 115. The

Fluctuation strength is dependent on the detection particles 106. In other words, the fluctuation intensity of the measurement signal 115 or the at least one property of the magnetic field represented by the measurement signal 115 is dependent on the presence of at least one detection particle 106 in the magnetic field.

The determination device 123 is signal-transmitting with the

Detection device 122 connected. The determination device 120 is designed to determine a binding state of at least one of the binding forces as a function of the fluctuation intensity determined by the determination device 122

Detection particle 106 in the magnetic field as unbound or bound to a detected particle 104 to determine. Based on the

determined binding state of the at least one detection particle 106, the particles 104 in the sample 102 can be detected qualitatively and / or quantitatively.

For example, the determination device 123 is designed to be the

Determine binding state as unbound if the detected

Fluctuation strength is in a first range of values. Furthermore, the

Determining means 123 adapted to the binding state as on Particle 104 to be detected bound to determine if the determined fluctuation strength is in a second range of values. In this case, the second value range represents lower fluctuation strengths than the first value range. Thus, a lower fluctuation strength or a fluctuation strength in the second value range corresponds to a bound state of the

Detection particle 106, wherein a higher fluctuation strength or a fluctuation strength in the first value range corresponds to an unbound state of the detection particle 106.

The microfluidic system 100 has according to the one shown in FIG

Embodiment further comprises a microfluidic channel 140. The microfluidic channel 140 is shaped to receive the sample 102 at the

Passing magnetic field sensor 130 over. Thus, the sample 102 is in the

Representation in Fig. 1 in the microfluidic channel 140 includes or arranged.

According to the exemplary embodiment illustrated in FIG. 1, the interface 110 with the coupled magnetic field sensor 130 is arranged adjacent to the sample 102 or to the microfluidic channel 140. According to a further embodiment, additionally or alternatively, the detection device 120 is arranged adjacent to the sample 102 or to the microfluidic channel 140. Optionally, the interface 110 is configured to accommodate the

Magnetic field sensor 130 in contact with a wall of the microfluidic channel 140 to arrange or move.

For example, the sample 102 contains biological material, wherein the particles 104 to be detected are biological particles, in particular cells, organic molecules or the like. In this case, the detection particles 106 are designed to bind to antibodies and / or surface proteins of the

To be detected particles 104 to bind.

According to one exemplary embodiment, the detection particles 106 may additionally or alternatively be designed as paramagnetic detection particles 106. According to the exemplary embodiment illustrated in FIG. 1, the microfluidic system 100 has a generating device 150 for generating the magnetic field. In particular, the generating device 150 is designed to generate a homogeneous magnetic field. According to another

Embodiment, the generating device 150 is designed to be a

To generate magnetic field in which at least one detection particle 106 adjacent to the magnetic field sensor 130 is immobilized.

Furthermore, according to the exemplary embodiment shown in FIG. 1, the microfluidic system 100 has an optional circulation device 160. The

Recirculation device 160 is configured to agitate or circulate sample 102, particularly within microfluidic channel 140. Recirculation device 160 is configured, for example, as a pump or stirrer.

According to the embodiment shown in Fig. 1, the

Detection device 120 signal transmitting capable connected to the generating device 150 and the circulating device 160. Here is the

Detection device 120 formed to at least one drive signal 170 to the generating device 150 and / or the circulation device 160th

issue. Thus, the generating means 150 and / or the

Umwälzeinrichtung 160 at least among others by the drive signal 170 of the detection device 120 controllable. FIG. 2 shows a flow diagram of a method 200 for the detection of

Particles in a sample according to an embodiment. The method 200 for detection can be carried out in conjunction with the detection device from FIG. 1 or a similar detection device. Also, the method 200 may be practiced for detection in conjunction with the microfluidic system of FIG. 1 or a similar microfluidic system.

The method 200 for detection comprises a step 210 of reading in a measurement signal from an interface to at least one magnetic field sensor. In this case, the measurement signal represents at least one detected property of at least one subset of the sample extending therethrough Magnetic field. Added to the sample are magnetic detection particles which are designed to bind to the particles to be detected.

In a step 220 of the determination, which can subsequently be carried out with respect to the step 210 of the read-in, in the method 200 one of the

Detective particles dependent fluctuation strength of at least one

Property of the magnetic field determined. Further, in a step 220 of determining thereupon, a binding state becomes at least one depending on the fluctuation intensity determined in the step 220 of the determination

Detection particles as unbound or bound to a detected particle determined.

By performing the steps of method 200, the particles in the sample can be qualitatively and / or quantitatively detected. Here, the read-in step 210, the determination step 220, and the determination-determining step 230 are repeatably executable, for example, for a plurality of detection particles n in succession.

According to one embodiment, the method 200 for detecting comprises a step 240 of adding a predefined amount of magnetic

Detection particles to the sample. In this case, the step 240 of the addition is executable before the step 210 of the read-in. In this case, detection particles which are designed to bind to antibodies and / or surface proteins of the particles to be detected if the particles to be detected are biological particles can be added in step 240 of the adding. Additionally or alternatively, in step 240 of adding, paramagnetic

Detection particles are added to the sample.

According to a further embodiment, the method 200 for detecting comprises a step 250 of generating, wherein the magnetic field is generated. In this case, the step 250 of generating is executable prior to the step 210 of the read-in. For example only, the step 250 of generating between the step 240 of the admit and the step 210 of the read in is executable. In this case, the measurement signal read in in step 210 of the read-in represents at least one property of that generated in step 250 of the generation Magnetic field. Optionally, in step 250 of generating, a homogeneous magnetic field is generated as the magnetic field. Additionally or alternatively, in step 250 of generating, a magnetic field is generated that is configured to immobilize at least one detection particle adjacent to the at least one magnetic field sensor.

According to yet another embodiment, the method 200 for detecting comprises a step 260 of circulating the sample with the added detection particles. The recirculation step 260 can be implemented, for example, by stirring or pumping the sample. In this case, the step 260 of

Circulating optionally prior to the step 210 of reading in parallel to the step 210 of reading in, the step 220 of determining and determining step 230, after the step 230 of determining and / or between the step 230 of determining and subsequently performing the

Step 210 of reading in executable.

Fig. 3 shows a diagram of magnetic field strengths over time. In this case, the time is plotted on an abscissa axis of the diagram labeled x, in particular in arbitrary units, with an inscription labeled y

Ordinatenachse of the diagram measured magnetic field strengths are plotted, which are represented in measurement signals. The measurement signals are possible measurement signals which are generated in the detection device from FIG. 1 or a similar detection device or the microfluidic system from FIG. 1 or a similar microfluidic system.

are processed.

A first graph 304 represents a first measurement signal having a first fluctuation width. The first graph 304 represents a measurement signal for a particle bound to a detected particle

Detection particles. In this case, the first graph 304 has a low

Fluctuation strength on, d. H. the changes in the signal within a time step are small.

A second graph 306 represents a second measurement signal having a second fluctuation amount. The second graph 306 represents a measurement signal for a freely moving detection particle without binding to a particle to be detected. In this case, the second graph 306 has a high fluctuation strength, that is, the changes of the signal within one

Time steps are high and higher than in the first graph 304.

As particles move freely in a liquid, they make an erratic path due to collisions with liquid molecules (Brownian motion). If a position of a particle over the time r _{t is} known, the result for the mean displacement square is without external forces where f is the number of dimensions, Do is the diffusion coefficient and Etc is the time elapsed between the measurement of the two positions r _t + At and r _t . For a spherical particle, the diffusion coefficient Do is inversely proportional to the radius of the particle.

In the following, the proportionality factor 2 f Do of equation (1) is generally referred to as fluctuation strength Φ _Γ .

In addition to translation, the collisions with the fluid molecules produce an erratic rotation of the particle.

Moves a magnetic particle, such as the detection particles of Fig. 1 and Fig. 2, by a liquid within a vessel, on the wall of an example one-dimensional magnetic field sensor, for. As Hall sensor, AMR or GMR magnetometer, MEMS sensor or SQUID, is attached, the measured magnetic field strength will fluctuate over time. The reason for this is a changing distance between particle and magnetic field sensor and a change in the direction of the magnetic field due to a rotation of the particle. From the measurement of the field strength over time, a fluctuation strength ΦΒ can be determined analogously to equation (1). The fluctuation strength ΦΒ is higher the smaller the particle is. In other words, the fluctuation amount ΦΒ will decrease as the magnetic detection particle binds to a particle to be detected, for example, a cell to be detected or the like is because the magnetic detection particle and the particle to be detected move together through the sample or the liquid.

Fig. 4 shows a schematic sectional view of a part of a

Microfluidic system 100 according to one embodiment. The microfluidic system 100 here corresponds to the microfluidic system of FIG. 1 or a similar microfluidic system, wherein in the illustration of FIG. 4, only a partial section of the microfluidic system is shown in a more detailed manner compared to FIG. The microfluidic system 100 has, according to the exemplary embodiment illustrated in FIG. 4, a polymeric multilayer structure.

Thus, in FIG. 4 of the microfluidic system 100, the magnetic field sensor 130, the microfluidic channel 140, a holding device 410 for holding the

Magnetic field sensor 130, a first polymer substrate 441 with the microfluidic channel 140, a second polymer substrate 442, a polymer membrane 444 and a recess 445 and a recess portion 445 in the second polymer substrate 442 shown.

The interface for coupling with the magnetic field sensor 130 is in this case designed as a part of the holding device 410, which is not explicitly shown in FIG. 4. Alternatively, the fixture 410 may represent the interface.

In other words, Fig. 4 shows a cross section through a

Multilayer structure of the microfluidic system 100, consisting of two polymer substrates 441 and 442 separated by a flexible polymer membrane 444. In the first polymer substrate 441, the microfluidic channel 140 extends. In the second polymer substrate 442 is the

Recess portion 445 formed so that in this area

Polymer membrane 444 is exposed or exposed. The magnetic field sensor 130 is attached to the holding device 410.

For carrying out a test of a sample or for detecting particles in a sample, for example according to the method of FIG. 2 or a similar method, the holding device 410 is moved in the direction of the Multilayer structure pushed, in particular in the recess portion 445 in until the magnetic field sensor 130 has contact with the polymer membrane 444.

Fig. 5 shows a schematic sectional view of a part of a

Microfluidic system 100 according to one embodiment. Here, the microfluidic system 100 in FIG. 5 corresponds to the microfluidic system from FIG. 4, or the illustration in FIG. 5 corresponds to the illustration from FIG. 4, with the exception that the microfluidic system attached to the holding device 410

Magnetic field sensor 130 is arranged in Fig. 5 in contact with the polymer membrane 444 or moved.

According to the exemplary embodiment illustrated in FIG. 5, the magnetic field sensor 130 is pressed into the polymer membrane 444, so that the polymer membrane 444 is deformed. In this way, it can be achieved that the magnetic field sensor 130 has a full contact with the polymer membrane 444 and is thus close to a sample when it is passed through the microfluidic channel 140.

With reference to Figures 1, 4 and 5, examples of sizes, materials and dimensions are set forth below.

For example, a detection interval or measuring interval Et may be 1

Microseconds to 100 milliseconds, in particular 100 microseconds to 10 milliseconds. One measurement period per particle can be at

Embodiments without circulation or flow 10 seconds to 10 minutes, in embodiments with circulation or flow, d. H. a residence time of the detection particle 106 in the detection area of the

Magnetic field sensor 130, for example 500 milliseconds to 30 seconds. A field strength of a homogeneous magnetic field can be, for example, 10 microtesla to 1000 millitesla, in particular 500 microtesla to 500 millitesla. A diameter of the magnetic detection particles 106 may be, for example, 100 nanometers to 100 micrometers, especially 500

Nanometers to 10 microns.

Examples of materials for the polymer substrates 441 and 442 include polymers, especially thermoplastics, e.g. As PC, PP, PE, PMMA, COP, COC, wherein for the Polymeric membrane 444 can be used for example elastomers, thermoplastic elastomers, thermoplastics, hot-melt adhesive films or the like.

A thickness of the polymer substrates 441 and 442 may be, for example, 0.1 mm to 10 mm, in particular 1 mm to 3 mm. A thickness of the polymer membrane 444 may be, for example, 5 microns to 500 microns, especially 50 microns to 150 microns.

The cross-sectional dimensions of the microfluidic channel 140 may be 10 by 10 square microns to 3 by 3 square millimeters, more preferably 100 by 100 square microns to 1 by 1 square millimeter.

With reference to Figs. 1 to 5 will be hereinafter

Embodiments, principles and advantages summarized and / or explained in other words.

In the method 200 for detecting particles 104 or cells, magnetic detection particles 106 are used, which in the case of

Immunoassays by an immune reaction specifically bind to detectable cells or particles 104. After adding the detection particles 106 into the sample 102, the magnetic field sensor 130 is used to determine the strength and / or direction of the magnetic field over time of at least one detection particle 106 in at least one spatial dimension. From the recorded measurement signal 115, the fluctuation intensity is determined in the next step 220. The intensity of fluctuation for a detection particle 106 without binding to a cell or a particle 104 differs from that of a detection particle 106 bound to a cell or a particle 104. Thus, it is possible to detect the presence of the cells or particles 104 to be detected via the

To determine fluctuation strength.

According to one exemplary embodiment, the microfluidic system 100 is embodied as a polymeric multilayer structure which has an interface 110 to, for example, a magnetic field sensor 130. The magnetic field sensor 130 can be arranged in or adjacent to a drive unit for the lab-on-chip system or microfluidic system 100. According to one embodiment, the method for detecting comprises the following steps:

Providing a sample 102 in a sample vessel;

Providing a magnetic field sensor 130 in the vicinity of the sample vessel, in particular in contact with the wall of the sample vessel;

Add 240 of magnetic detection particles 106, for example, suspended in a liquid, wherein the detection particles 106 bind to the cells or particles 104 to be detected, for example, with

antibodies;

Measuring or detecting the magnetic field strength over time;

Calculate or determine 220 of the fluctuation strength ΦΒ, such as with

Referring to Fig. 3 described; and

Determining 230 the binding state from the fluctuation strength.

In this case, the concentration of the magnetic detection particles 106 is selected, for example, in step 240 of the addition so that in each case only a single detection particle 106 is arranged within a range of the magnetic field sensor 130.

According to one exemplary embodiment, in the method 200 for detection after the measurement of a detection particle 106 and identification of its binding state, the step 260 of the circulation is carried out so that a circulation of the sample 102 takes place and another detection particle 106 can be measured. The circulation can take place for example via a stirrer or by external / internal pumps.

According to a further embodiment, a three-dimensional

Magnetic field sensor 130 used. This makes it possible to at least partially separate a rotational component of the fluctuation intensity from a translation component. Such an embodiment has the particular advantage that the binding state can be determined by means of two separate variables, ie rotational component and translation component, and thus an even higher level of certainty in the detection of the binding state can be achieved. According to another embodiment, the sample 102 is within the

Range of the magnetic field sensor 130 at least during the measuring process of a homogeneous magnetic field interspersed, generated in step 250 of the generating z. B. via a Helmholtz coil arrangement. In this way, the magnetic moments of the detection particles 106 align within the homogeneous magnetic field and a rotational movement is prevented.

In one embodiment, paramagnetic detection particles 106 are used in step 240 of adding. As a result, the magnetic moment of the detection particles 106 is formed in combination with the homogeneous magnetic field. This embodiment has

In particular, the advantage that the detection particles 106 in the sample 102 outside of the homogeneous magnetic field exert no attractive interaction with each other and thus coagulation of the detection particles 106 is prevented.

The fact that the rotational movement of the detection particles 106 is suppressed in the aforementioned ways has the advantage that the measured field strength H is merely a function of the distance d to

Magnetic field sensor 130 is. If this function is known, for example, by means of appropriate simulations, the measurement signal H (t) 115 can be used to directly generate a

Trajectory d (t) of the detection particles 106 derived. With the aid of equation (1), the diffusion coefficient Do and thus the radius of the detection particle 106 can be calculated from the trajectory d (t). This has the advantage that a known quantity, the radius of the free or unbound detection particle 106, is obtained as the measured value and thus, for example, an exact and reliable calibration can be carried out. In this case, it is favorable to additionally consider that the diffusion coefficient Do in the vicinity of a wall is not constant, but depends on the distance to the wall. Of the

Diffusion coefficient Do at the distance z from the wall can be determined from the trajectory d (t), if for each distance z equation (1) with the condition Zstart = z is evaluated. This has the particular advantage that the

Diffusion coefficient Do and thus the radius can be determined more accurately. According to another embodiment, the magnetic field sensor 130 is in

Contact with the microfluidic channel 140 is arranged and the sample 102 including the magnetic detection particles 106 is through the

microfluidic channel 140 pumped, for example by external or microfluidic integrated pumps. Once a detection particle 106 on

Magnetic field sensor 130 generates a measurement signal 115, the flow is stopped and the binding state of the detection particle 106 is evaluated. Subsequently, the process for the next detection particle 106 is repeated. This has the particular advantage that the binding state of each detection particle 106 can be determined exactly once. In addition, the detection particle 106 can be positioned accurately over the magnetic field sensor 130, so that a high measurement signal 115 can be generated. In addition, this allows to determine the number of detection particles 106, each to a

have to be detected cell or a detected particle 104 bound and which not. In this way a concentration of the

Estimate the cells or particles 104 to be detected.

According to yet another embodiment, the magnetic field may be generated in step 250 of the generating so that a potential well is formed in the vicinity of the magnetic field sensor 130 for the detection particle 106, i. H. in the sense of a so-called Magnetic Tweezers. That way that can

Detection particles 106 are more closely held in the vicinity of the magnetic field sensor 130.

According to one embodiment, the sample 102 is continuously pumped through the microfluidic channel 140 in step 260 of the circulation and the

Measurement of the Detection Particles 106 While Passing on

Magnetic field sensor 130 performed. It is advantageous to discard low-frequency components on the measurement signal 115 before the evaluation of the measurement signal 115, which are due to the variable distance to the magnetic field sensor 130 during the

Passing by arise. Additionally, it makes sense to change the interval et between To keep measurements as small as possible in order to minimize the proportion of the signal between two measuring points, which is caused by the constant relative movement between the detection particles 106 and magnetic field sensor 130. To the recorded amount of data per detection particles 106 and thus the

To increase the accuracy of the measurement, the liquid or sample 102 conducted past the magnetic field sensor 130 can be guided past the magnetic field sensor 130 at least a second time. This can be the

Determine the probability that a detection particle 106 has bound to a cell or particle 104 to be detected. The concentration of the cells or particles 104 to be detected can thus also be determined via the known concentration of the detection particles 106.

Lab-on-chip systems or microfluidic systems 100 are common

Disposable parts, which are only used for one measurement. For the application of the method 200 for the detection, it is therefore advantageous to detachably couple the magnetic field sensor to a disposable component, ie to offer an interface 110 to the magnetic field sensor 130, which can be arranged in a drive unit for the lab-on-chip system. This reduces costs for the lab-on-chip system or microfluidic system 100. In addition, more complex and accurate magnetic field sensors 130 can be used.

The aforementioned multi-step immunoassay workflow may be shortened according to embodiments. For example, it eliminates all washing steps and the sample 102 only needs to be added a substance, a buffer with functionalized magnetic detection particles 106. This process times and material costs can be reduced. In addition, the shortened workflow can be more easily integrated into lab-on-chip systems or microfluidic systems 100.

In contrast to conventional detection methods, only a few probes, such as, for example, magnetic detection particles 106 or fluorescence-labeled molecules, are used to obtain a usable one

Receive measurement signal 115. The detection method 200 allows the bonding state of a single magnetic detection particle 106 to be increased determine. This makes it possible to detect a single cell or a single particle 104.

The detection method of the method 200 for detection or under

Use of the detection device 120 and the microfluidic system 100 is contact-free and does not require optically transparent access. Since magnetic fields usually penetrate non-conductive substances without appreciable damping, there are great freedoms in the selection of materials.

In particular, it is possible to use the method 200 for detecting also through the skin of a patient for magnetic detection particles 106 in a blood vessel. This allows a patient to use magnetic beads

Detection particles 106 are injected, the binding state can be monitored continuously, for example via a magnetic field sensor 130 on the wrist, z. B. integrated into a smartwatch or the like. This can be used, for example, for the early detection of cancer, pathogens, viruses or for the follow-up of therapies.

In contrast to lab-on-chip systems with magnetic field sensors, which are integrated directly into parts for single use, the interface 110 enables a magnetic field sensor 130, for example located in the drive system for the lab-on-chip system 100, in close proximity to the sample 102 to position. Since the magnetic field sensor 130 can be used multiple times or in several microfluidic systems 100, costs for a lab-on-chip system or microfluidic system 100 can be reduced.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

Claims

claims

A method (200) for detecting particles (104) in a sample (102), the method (200) comprising:

Reading (210) a measurement signal (115), which represents at least one detected property of a magnetic field extending at least through a subset of the sample (102), from an interface (110) to at least one magnetic field sensor (130), wherein the sample (102 ) magnetic detection particles (106) are added, which are adapted to bind to the particles to be detected (104);

Determining (220) a fluctuation intensity of the at least one property of the magnetic field that is dependent on the detection particles (106); and

Determining (230) a binding condition of at least one

Detection particle (106) as unbound or bound to a particle to be detected (104) depending on the determined

Fluctuation intensity to the particles (104) in the sample (102)

demonstrated.

2. The method (200) according to claim 1, wherein in step (230) of the

Determining the binding state as unbound when the intensity of fluctuation is in a first range of values, wherein in step (230) of determining the binding state is determined to be bound to a particle (104) to be detected if the intensity of fluctuation is in a second range of values, the lower one Fluctuation strengths represented as the first range of values. Method (200) according to one of the preceding claims, wherein in step (210) of the read-in a measuring signal (115) is read in, which represents a strength and / or direction of the magnetic field over time.

The method (200) according to one of the preceding claims, comprising a step (240) of adding a predefined amount of the magnetic detection particles (106) to the sample (102).

The method (200) according to claim 4, wherein in step (240) of adding detection particles (106) are added which are adapted to bind to antibodies and / or surface proteins of the

The particles (104) to be detected are biological particles, and / or paramagnetic detection particles (106) are added to the sample (102) in step (240) of addition.

Method (200) according to one of the preceding claims, comprising a step (250) of generating the magnetic field, wherein the measurement signal (115) read in in step (210) of the read-in represents at least one property of the generated magnetic field.

A method (200) according to claim 6, wherein in the step (250) of generating a homogeneous magnetic field is generated as the magnetic field and / or a magnetic field is generated, which is formed to at least one detection particle (106) adjacent to the at least one magnetic field sensor (130) to immobilize.

The method (200) according to one of the preceding claims, comprising a step (260) of circulating the sample (102) with the

added detection particles (106), wherein the step (260) of the circulation before, during and / or after detecting the at least one property of the magnetic field is executable. Detection device (120) arranged to execute steps of the method (200) according to one of the preceding claims in corresponding units.

A microfluidic system (100) for inspecting a sample (102), comprising: a detection device (120) according to any one of the preceding claims; and an interface (110) for coupling to the at least one magnetic field sensor (130), the measurement signal (115) being across the

Interface (110) to the detection device (120) is transferable.

The microfluidic system (100) according to claim 10, comprising a microfluidic channel (140) in which the sample (102) is feasible, wherein the detection device (120) and / or the interface (110) are arranged adjacent to the microfluidic channel (140) are.

The microfluidic system (100) of claim 11, wherein the interface (110) is configured to receive the at least one

Magnetic field sensor (130) in contact with a wall of the microfluidic channel (140) to arrange or move.

The microfluidic system (100) of any of claims 10 to 12, comprising at least one magnetic field sensor (130) removably coupled or coupleable to the interface (110).

A computer program adapted to execute the method (200) according to any one of the preceding claims.

A machine readable storage medium storing the computer program of claim 14.