Microfluidic component suitable for characterizing a biological object

Abstract

The invention relates to a microfluidic component used for electrical impedance measurement through a biological object (O), said microfluidic component comprising: - A support in which is made a main microfluidic channel (C_1) defining a path for the circulation of a fluid containing the biological object (O), - A trapping device positioned in the main microfluidic channel (C_1) on the circulation path of said biological object, - At least one first electrode and a second electrode intended to be each brought to a distinct electrical potential, in order to perform said impedance measurement, - Said trapping device being composed of at least one first central pillar (P_1) and a second central pillar (P_2) positioned inside the microfluidic channel, - The first central pillar being configured to form the first electrode and the second central pillar being configured to form the second electrode.

Description

Technical field of the invention

[0001] The present invention relates to a microfluidic component used for electrical impedance measurement through a biological object, this component being able to be used to characterize the biological object, in particular for the purpose of studying its viability. State of the art

[0002] Studies are currently underway to better characterize a biological object such as a spheroid formed by a cluster of biological cells. This characterization focuses particularly on the viability of the biological cells that compose the spheroid. Studies show that there may be a correlation between the viability of cells present in the spheroid and electrical impedance measurements across the spheroid. Transepithelial / transendothelial electrical resistance (TEER) is a widely accepted quantitative technique for measuring the integrity of tight junction dynamics in cell culture models of endothelial and epithelial monolayers. TEER values ​​are good indicators of the integrity of cell barriers before they are evaluated for drug or chemical transport.TEER measurements can be performed in real time without damaging the cells and are generally based on measuring ohmic resistance or impedance over a wide frequency spectrum.

[0003] In other words, the higher the electrical impedance measured across the spheroid, the more living cells the spheroid contains. Although this relationship is not yet fully established, numerous studies are attempting to demonstrate it. These studies rely on the use of microfluidic devices for measuring electrical impedance. Examples include the following studies: Wu_2018 - Electrical impedance tomography for real-time and label-free cellular viability assays of 3D tumor spheroids - Analyst / University of Edinburgh .Viswam_2018 - Impedance Spectroscopy and Electrophysiological Imaging of cells with a high-density CMOS microelectrode array system - IEEE Transactions on biomedical circuits and systems / Ecole polytechnique de Zurich (ETH) Heileman_2015 - Microfluidic platform for assessing pancreatic islet functionality through dieletric spectroscopy - Biomicrofluidics / McGill University, Montreal

[0004] However, the various methods used in these studies are not satisfactory for the following reasons: The electrodes used are coplanar, and the biological objects to be characterized are either in contact with the electrodes or too far away. In some cases, the magnetic field lines produced between the electrodes will not optimally penetrate the biological objects being characterized. The materials used for integrating the electrodes into these fluidic systems are often not transparent (electrode or chamber materials), or the device configuration is not suitable for visualizing and monitoring the biological object. It is often impossible to implement transmission microscopy monitoring, yet this observation method is a standard in biology. These systems are not suitable for perfusion of the trapped biological object.

[0005] US patent 8454813B2 describes a cell sorting device (cytometer). This device is not intended to characterize a biological object through measurements. The electrodes are positioned so that the resulting field forces the cell against the bottom of the well.

[0006] Patent application US2010 / 270176A1 describes a device for characterizing neurons. This device uses coplanar electrodes arranged at the bottom of the cavity. This solution allows the biological object to be pressed against the bottom of the cavity, which is not optimal for characterizing it through measurements.

[0007] Patent EP4147780B1 describes the principle of characterizing a biological object by impedance measurements, using electrodes integrated into the substrate. The electrodes are made as conductive deposits and are arranged so that the field lines pass through the biological object.

[0008] This latter solution, however, has some drawbacks. It does not allow for measurements to be taken very close to the biological object. Its design does not allow for perfusion of the trapped biological object. It is also not suitable for monitoring the fluidic environment surrounding the biological object.

[0009] Patent application WO2022 / 084821A1 describes a deterministic lateral displacement (DLD) particle sorting device. This device comprises pillars, each serving as an electrode. The combination of the DLD principle and electrophoresis notably increases the device's sorting throughput.

[0010] US patent application 2012 / 129192A1 describes a cancer cell detection (CTC) device, using an array of metallic nanoneedles that can be used to measure the resistance of cells captured between two pairs of distinctly polarized nanoneedles.

[0011] The aim of the invention is to provide a method for easily monitoring a biological object and / or its surrounding fluidic environment. Description of the invention

[0012] This goal is achieved by a process for characterizing a biological object in its surrounding environment, implemented using a measurement system comprising a microfluidic component and a potentiostat, this microfluidic component being used for measuring electrical impedance through said biological object present in a surrounding fluidic environment, said microfluidic component comprising: A support in which a main microfluidic channel is formed, defining a path for the circulation of a fluid containing the biological object; a trapping device positioned in the main microfluidic channel on the circulation path of said biological object, this trapping device defining a trapping zone; said trapping device is composed of at least a first central pillar and a second central pillar positioned inside the main microfluidic channel; the first central pillar carrying a first electrode and the second central pillar carrying a second electrode; the support comprising a first lateral channel connected to the main microfluidic channel by a first junction zone and a second lateral channel connected to the main microfluidic channel by a second junction zone, the first junction zone and the second junction zone being located opposite the trapping device.The component comprising a first series of one or more lateral pillars positioned at the first junction zone and a second series of one or more lateral pillars positioned at the second junction zone, each lateral pillar of the first series and the second series also carrying a separate electrode intended to be held at an electrical potential, each electrode being connected to said potentiostat to be held at an electrical potential, The said process consists of: Select an area of ​​interest to monitor in the microfluidic component, said area being chosen from the biological object trapping area, the first junction area and the second junction area containing the surrounding fluidic medium, Apply a first electrical potential to the electrode of the first central pillar, a second electrical potential to the electrode of the second central pillar, a third electrical potential to the electrode of each lateral pillar of the first series and a fourth electrical potential to the electrode of each lateral pillar of the second series, taking into account the selected area of ​​interest, The first electrical potential, the second electrical potential, the third electrical potential and the fourth electrical potential being each chosen taking into account the selected area of ​​interest to come to monitor that area of ​​interest.

[0013] Another objective of the invention is also to propose a system integrating a microfluidic component enabling the characterization of a biological object and which is: Suitable for performing reliable electrical impedance measurements as close as possible to the biological object; Suitable for enabling perfusion of the biological object; Feasible using already mastered manufacturing technologies; Suitable for monitoring the fluidic environment surrounding the biological object;

[0014] This goal is achieved by a system for measuring electrical impedance through a biological object, comprising a microfluidic component and a potentiostat, the microfluidic component comprising: A support in which a main microfluidic channel is formed, defining a path for the circulation of a fluid containing the biological object; a trapping device positioned in the main microfluidic channel on the circulation path of said biological object, this trapping device defining a trapping zone; said trapping device is composed of at least a first central pillar and a second central pillar positioned inside the main microfluidic channel; the first central pillar carrying a first electrode and the second central pillar carrying a second electrode; the support comprising a first lateral channel connected to the main microfluidic channel by a first junction zone and a second lateral channel connected to the main microfluidic channel by a second junction zone, the first junction zone and the second junction zone being located opposite the trapping device.The component comprising a first series of one or more lateral pillars positioned at the first junction zone and a second series of one or more lateral pillars positioned at the second junction zone, each lateral pillar of the first series and the second series also carrying a separate electrode intended to be held at an electrical potential, each electrode being connected to said potentiostat to be held at an electrical potential, A processing unit of the system is configured to analyze measurement data generated by the implementation of the process defined above and to determine properties of the trapped biological object and / or its surrounding environment.

[0015] According to one particular feature, the main microfluidic channel extends lengthwise along a longitudinal axis and has a constant cross-section over at least part of its length, the first central pillar and the second central pillar being positioned symmetrically on either side of said longitudinal axis.

[0016] According to another feature, the trapping device has a third central pillar and a fourth central pillar positioned symmetrically on either side of said longitudinal axis, the third central pillar being located on the same side relative to the longitudinal axis as the first central pillar and the fourth central pillar on the same side as the second central pillar.

[0017] According to another peculiarity, the third central pillar carries a third electrode and the fourth central pillar carries a fourth electrode.

[0018] According to another peculiarity, the trapping device has a fifth central pillar, called the median pillar, positioned along the longitudinal axis, the median pillar carrying a fifth electrode, intended to be put at a neutral electrical potential.

[0019] Another distinctive feature is that the central pillars of the trapping device are positioned along an arc of a circle.

[0020] Another distinctive feature is that the central pillars of the trapping device each have a circular cross-section.

[0021] According to another distinctive feature, the first central pillar and the second central pillar each have a kidney-shaped cross-section.

[0022] Another distinctive feature is that each lateral pillar has a triangular cross-section.

[0023] Another distinctive feature is that each lateral pillar has a hemispherical shape. Another distinctive feature is that the support structure includes an intermediate layer made of a doped silicon-type material, this intermediate layer being configured to form each pillar.

[0024] According to another distinctive feature, the intermediate layer includes a body constructed around said pillars, configured to be electrically insulating. Brief description of the figures

[0025] Other features and advantages will appear in the detailed description that follows, in conjunction with the attached figures listed below: There figure 1 illustrates, in perspective, the principle of realizing the microfluidic component according to the invention, according to a first embodiment; The figure 2 represents, viewed from above, the microfluidic component according to the invention in the first embodiment; The figures 3A to 3Fshow different configurations of the microfluidic component; The Figures 4A to 4D illustrate, through current density simulations, the targeted area of ​​interest according to several distinct electrical configurations; The figure 5 represents an example of the realization of the multilayer structure of the microfluidic component support; Detailed description of at least one embodiment

[0026] In the following description, the terms "lower", "higher", "above", "below" or equivalent are to be considered taking into account the position of the microfluidic component on a horizontal support.

[0027] The term "longitudinal" is to be understood in the directions parallel to the horizontal support and the term "transverse" in the directions perpendicular to the horizontal support.

[0028] The invention aims in particular to enable the measurement of electrical impedance through a biological object O.

[0029] The biological object O is, for example, a cell aggregate. According to the invention, a cell aggregate is defined as the self-assembly of one or more cell types in three dimensions. Such a cell aggregate may be called, among other things, a spheroid, organoid, tumoroid, or neurosphere. This aggregate may also be an islet of Langerhans. In the following description, the term "biological object," referenced as O, will be used generically to refer to such an aggregate, as this term is commonly used in the field of live cell culture. Without limitation, such a biological object O may, for example, have a diameter ranging from a few tens of micrometers to a few hundred micrometers. Microfluidic component Figure 1 Figure 2

[0030] The microfluidic component of the invention includes a support.

[0031] The support may have a multi-layered structure (see below in connection with the figure 5 ).

[0032] The microfluidic component support includes a main microfluidic channel C_1. This channel advantageously has a rectangular cross-section. It extends straight along a designated longitudinal axis (X). It is designed to form a flow path for the biological object O to be analyzed. It thus includes an inlet through which the biological object O is introduced, and an outlet.

[0033] The component also includes a biological object trapping device, positioned inside the main microfluidic channel C_1, between its inlet and outlet.

[0034] According to the invention, the trapping device comprises at least two first pillars, referred to as central pillars P_1, P_2, erected in the main microfluidic channel C_1, interposed in the fluidic flow. These central pillars P_1, P_2 are erected (in a transverse direction) in the main microfluidic channel and are positioned so as to block the biological object O when it is injected into the main microfluidic channel along the longitudinal axis (X).

[0035] Advantageously, the two central pillars P_1, P_2 are positioned symmetrically, on either side of the longitudinal axis (X) of the main microfluidic channel C_1.

[0036] In an advantageous implementation shown on the figure 1 and on the figure 2The trapping device comprises four central pillars P_1, P_2. These four central pillars are also advantageously positioned symmetrically, two by two, on either side of the longitudinal axis (X) of the main microfluidic channel.

[0037] In another configuration, it is also possible to integrate a fifth central pillar, called the median pillar P_3, into the trapping device, positioned along the longitudinal axis (X) ( figure 3F (see below).

[0038] In an advantageous configuration, the central pillars of the trapping device are positioned to form an arc. The arc is shaped to create a concave space to receive the biological object O as it flows from the inlet to the outlet of the main microfluidic channel C_1.

[0039] According to a particular embodiment, the component can integrate into its support one or more lateral microfluidic channels C_20, C_30, each lateral channel having at least one junction zone Z_20, Z_30 with the main microfluidic channel C_1, through which it communicates with the main microfluidic channel C_1. On the figures 1 and 2 Two lateral channels, C_20 and C_30, are shown. Each lateral microfluidic channel, C_20 and C_30, is advantageously used to transport a culture medium suitable for the perfusion of the biological object O trapped by the trapping device. According to a specific feature, each junction zone, Z_20 and Z_30, is thus positioned opposite the trapping zone of the biological object O.

[0040] According to a particular and advantageous embodiment, the component comprises a series of one or more lateral pillars P_20, P_30 at each junction zone Z_20, Z_30 existing between a lateral microfluidic channel C_20, C_30 and the main microfluidic channel C_1. In other words, with two lateral microfluidic channels, two series of one or more lateral pillars are present at each junction zone. The two series of one or more lateral pillars are positioned symmetrically with respect to the longitudinal axis (X). Without limitation, the first series may comprise five lateral pillars P_20 and the second series may comprise five lateral pillars P_30. The lateral pillars P_20 of the first series and the lateral pillars P_30 of the second series are positioned symmetrically with respect to the longitudinal axis (X). In each series, the lateral pillars are advantageously aligned in a direction parallel to the longitudinal axis (X).

[0041] According to the invention, the component also incorporates several electrodes, used to perform impedance measurements across the biological object O when it is trapped by the trapping device. The electrodes are polarized and are therefore placed, in pairs, at distinct and opposite electrical potentials.

[0042] Opposite electrical potentials mean that the two potentials have the same magnitude but opposite signs (one is positive and the other is negative). For example, the positive electrical potential is set at +10 mV and the negative electrical potential at -10 mV. In the measurement technique used, namely electrochemical impedance spectroscopy, a sinusoidal potential is applied that oscillates between +10 and -10 mV.

[0043] According to the invention, each central pillar P_1, P_2 of the trapping device is configured to form a separate electrode.

[0044] In the case where lateral pillars P_20, P_30 are present, these are each configured to form a separate electrode.

[0045] Each electrode of the component can be placed at a distinct electrical potential.

[0046] In the following description, it is assumed that, as each pillar is configured to form an electrode, it can be placed at a particular electrical potential.

[0047] To position each pillar at a specific electrical potential, the microfluidic component is connected to a potentiostat, to which each electrode of the component is connected. The potentiostat is configured to regulate the electrical potential applied to each electrode. The potentiostat and the component thus form a complete measurement system for performing impedance measurements on the biological specimen.

[0048] Several advantageous options can be considered: The lateral pillars P_20 of the first series are placed at the same electrical potential; The lateral pillars P_30 of the second series are placed at the same electrical potential; The lateral pillars P_20 of the first series and the lateral pillars P_30 of the second series are at the same electrical potential or at opposite electrical potentials; The central pillars P_1, P_2 (with the exception of the middle pillar P_3) are placed at the same electrical potential; The central pillars are divided into a first series (pillars P_1) at a first electrical potential and a second series (pillars P_2) at a second electrical potential opposite to the first electrical potential; The middle pillar P_3 is placed at a neutral electrical potential;

[0049] By playing with these different options, we can change the configuration of the device and focus the analysis on one or more areas of interest.

[0050] Depending on the electrical potentials assigned to each pillar, different field lines are created, thus allowing the characterization of the biological object O and / or its surrounding environment. According to the invention, it is possible to activate each electrical potential independently and to create one or more field lines within the component. The various impedance measurements taken between two pillars are data collected for analysis. A processing unit can be configured to analyze this measurement data and determine properties of the trapped biological object O and / or its surrounding environment. Layout configurations Figures 3A to 3F

[0051] In conjunction with the attached figures, several configurations can be considered, though this list is not exhaustive. These configurations are given as examples and are not exhaustive.

[0052] First configuration - Figure 3A This is the simplest configuration, allowing the biological object O to be trapped while measurements are taken as close as possible to it. This configuration incorporates only two central pillars, P_1 and P_2, placed at two distinct and opposite electrical potentials (+10mV and -10mV). They are positioned symmetrically with respect to the longitudinal axis.

[0053] Second configuration - Figure 3B : this is a configuration with only four central pillars, a first series of two central pillars P_1 located on the same side of the longitudinal axis (X) being at the same first electrical potential (for example +10mV), and a second series of two central pillars P_2 located on the other side of the longitudinal axis (X) at a second electrical potential (for example -10mV), opposite to that of the first electrical potential.

[0054] Third configuration - Figure 3C: Four central pillars P_1, P_2 in two series (as in the second configuration) and at least two lateral pillars P_20, P_30, a first lateral pillar P_20 at the level of the first junction zone Z_20 and a second lateral pillar P_30 at the level of the second junction zone Z_30. The two central pillars P_1 of the first series, located on the same side of the longitudinal axis (X), are at the same first electrical potential (for example +10mV), and the two central pillars P_2 of the second series, located on the other side of the longitudinal axis (X), are at the same second electrical potential (for example -10mV), opposite to that of the first electrical potential.

[0055] The two lateral pillars P_20 and P_30 each have a distinct electrical potential, with the two potentials being opposite. Lateral pillar P_20 is at the same electrical potential (+10mV) as the central pillars P_1 of the first series. Lateral pillar P_30 is at the same electrical potential (-10mV) as the central pillars P_2 of the second series.

[0056] Fourth configuration - 3D Figure It is identical to the third configuration, with several lateral pillars P_20, P_30 for each series. On the 3D figureThus, five lateral pillars are used for each series of lateral pillars. The lateral pillars P_20 of the first series are all at the same electrical potential (for example, +10mV), and the lateral pillars P_30 of the second series are all at the same electrical potential (for example, -10mV), opposite to that applied to the pillars of the first series. The pillars (central and lateral) located on the same side of the longitudinal axis (X) are all at the same electrical potential, and the pillars located on the opposite side of the longitudinal axis (X) are at the opposite electrical potential.

[0057] Fifth configuration - Figure 3EIts structure is identical to that of the fourth configuration. However, the lateral pillars P_20 of the first series and those (P_30) of the second series are all at the same electrical potential (for example, +10mV). And the central pillars P_1 and P_2 are all at the same electrical potential (for example, -10mV), opposite to that applied to the lateral pillars.

[0058] Sixth configuration: This configuration is identical to the fourth configuration ( 3D figure ), with the addition of the median pillar P_3 located in the axis of the longitudinal channel (X). This pillar is placed at a neutral electrical potential (0mV). Manufacturing principles Figure 5

[0059] To form an electrode at the level of a pillar of the component, several solutions can be considered.

[0060] One solution would be to deposit a metallic layer on each pillar and integrate a via into the support to connect each pillar to the potentiostat. In this case, the intermediate layer incorporating the pillars could be made of silicon and hollowed out at each pillar to allow for the metallic deposit. It would also be possible to deposit a metallic layer directly onto the surface of each pillar. The metal could be replaced by a metal oxide, a conductive material such as graphene, amorphous carbon (DLC), a material like indium oxide (ITO) or molybdenum disulfide (MoS₂), or any other biocompatible electrically conductive material.

[0061] Another advantageous and illustrated solution is figure 5This involves creating the electrodes using a specific intermediate layer L_2 with conductive properties. For example, this intermediate layer L_2 incorporates the component's pillars. It is, for instance, made of doped silicon.

[0062] In this configuration of a conductive intermediate layer, the multilayer structure is, for example, as follows: A first lower layer L_1 advantageously made of an electrically insulating material, such as COC (Cyclo Olefin Copolymer), COP (Cyclo Olefin Polymer), or a PMMA (Polymethyl Methacrylate) type material. A second layer, forming the intermediate layer L_2, made of doped silicon, this second layer being shaped to create the central and lateral pillars (if present) – designated P_X on the figure 5; A third layer L_3 made of silica (SiO 2) integrating the electrical connections 10 to each pillar; A fourth layer L_4 forming a hood, made of glass and including the electrical tracks 11;

[0063] The manufacturing principle of the glass (L_4)-pillar interface is, for example, as follows: PVD (vapor deposition) of a 20nm titanium bonding layer onto the glass layer; PVD of a platinum layer onto the titanium layer; Deposition of the L_2 doped silicon layer; Deposition of a mask on the doped silicon layer to protect the areas intended to form the pillars and electrical connections; Plasma etching of the L_2 doped silicon layer to form the pillars;

[0064] By way of example, the intermediate silicon layer L_2 is N+ doped with arsenic. Its resistivity is given to be less than 3 mohm.cm.

[0065] As mentioned above, the electrical connections / tracks are, for example, made of platinum or gold.

[0066] It should be noted that when the intermediate layer L_2 is made of doped silicon, the entire intermediate layer L_2 has conductive properties, and therefore also the body of the support in which the main microfluidic channel C_1 and the lateral microfluidic channels C_20, C_30 are formed. However, it is also possible to make this volume electrically insulating and to make only the pillars of the structure conductive.

[0067] The central and lateral pillars can take various forms, but are not limited to: The central pillars P_1, P_2 can all be identical and cylindrical; Two central pillars located closest to the longitudinal axis (X) can have a kidney-shaped cross-section; The lateral pillars P_20, P_30 can have a triangular cross-section; The lateral pillars P_20, P_30 can have a semi-cylindrical shape; Any other shape could of course be considered. Generally speaking, it may be advisable to avoid shapes with sharp edges, in order to prevent point effects when creating field lines between the pillars.

[0068] Without limitation, the pillars have a suitable height, at most equal to the depth of the microfluidic channel and at least equal to half the largest dimension (e.g., its diameter) of the biological object O, in order to maintain effective trapping. For example, the cylindrical central pillars have a cross-section of 100 µm in diameter. The height of the triangular cross-section of the lateral pillars is also 100 µm. The electrical connections are, for example, thin platinum lines, 50 µm wide. The central pillars are, for example, spaced 80 µm apart, and the lateral pillars are, for example, spaced 45 µm apart. Functional simulations Figures 4A to 4E

[0069] Depending on the chosen geometric and electrical configuration, it is possible to observe a specific area of ​​interest (designated Z in the figures). Different configurations are shown below: Figure 4AThis is the fourth configuration described above, in which the central pillars p_1, P_2 are chosen to be cylindrical and the lateral pillars p_20, P_30 to be semi-cylindrical in shape. The body of the intermediate layer L_2 is electrically isolated. On one side of the longitudinal axis, the two central pillars P_1 and the lateral pillars P_20 are at the same electrical potential (+10mV) and on the other side of the longitudinal axis, the two other central pillars P_2 and the other lateral pillars P_30 are at the opposite electrical potential (-10mV).

[0070] We note that the impedance measurement at 1MHz is concentrated on a Z zone which typically corresponds to the zone where the biological object O is positioned when it is trapped in the component.

[0071] Figure 4BThis is also the fourth configuration described above, in which triangular-sectioned lateral pillars P_20 and P_30 are used. It can thus be seen that it is possible to focus the measurements on a zone Z that corresponds to the trapping zone of the biological object.

[0072] Figure 4C We retain the same geometric and electrical configuration as that of the figure 3EAll central pillars P_1 and P_2 are set to the same electrical potential (e.g., -10 mV), and all lateral pillars P_20 and P_30 are set to the opposite electrical potential (+10 mV). Numerical simulations show that, in this configuration, impedance measurements will preferentially be taken over a region Z corresponding to that occupied by the surrounding medium, with the exception of the area where the biological object is trapped. Such a current distribution is quite useful for performing reference measurements; for example, it will be possible to characterize the solution present in the surrounding medium, without the biological object O.

[0073] Figure 4D This is the configuration with five central pillars ( figure 3F), including a central pillar P_3 located on the longitudinal axis and at a neutral electrical potential. The two central pillars P_1 and the lateral pillars P_20 located on the same side of the longitudinal axis (X) are at the same electrical potential (+10mV), and the two other central pillars P_2 and the other lateral pillars P_30 located on the opposite side of the longitudinal axis (X) are at the opposite electrical potential (-10mV). The body of the intermediate layer L_2 is electrically isolated. In this configuration, it is possible to study a zone Z, which corresponds to the trapping zone of the biological object.

[0074] Figure 4EThis configuration involves changing the shape of two central pillars, P_1 and P_2 (one from each series), located closest to the longitudinal axis (X). These are shaped into a kidney-like form. The lateral pillars, P_20 and P_30, are chosen with a semi-cylindrical shape. The body of the intermediate layer, L_2, is electrically insulated. Electrically, the central pillars P_1 and lateral pillars P_20 are at the same potential (+10mV), while the central pillars P_2 and lateral pillars P_30 are at opposite potentials (-10mV). In this configuration, it is possible to focus on a Z zone, which corresponds to the trapping zone of the biological object. Furthermore, there are fewer losses with the semi-cylindrical shape of the lateral pillars P_20 and P_30.

[0075] The solution of the invention thus makes it possible to fulfill the function of trapping the biological object O as well as the function of impedance measurement, by allowing one to get as close as possible to the trapped biological object O.

[0076] Furthermore, the different possible connection configurations allow targeting, as desired, different areas of interest, including the biological object or its surrounding environment.

[0077] Finally, manufacturing using an intermediate layer L_2 of doped silicon, this intermediate layer integrating the pillars, simplifies the manufacturing process.

Claims

1. A method for characterizing a biological object in its surrounding environment, implemented using a measurement system comprising a microfluidic component and a potentiostat, this microfluidic component being used for measuring electrical impedance through said biological object (O) present in a surrounding fluidic medium, said microfluidic component comprising: - A support in which a main microfluidic channel (C_1) is formed, defining a path for the circulation of a fluid containing the biological object (O), - A trapping device positioned in the main microfluidic channel (C_1) on the circulation path of said biological object, this trapping device defining a trapping zone, - Said trapping device is composed of at least a first central pillar (P_1) and a second central pillar (P_2) positioned inside the main microfluidic channel.- The first central pillar carrying a first electrode and the second central pillar carrying a second electrode, - The support comprising a first lateral channel (C_20) connected to the main microfluidic channel (C_1) by a first junction zone (Z_20) and a second lateral channel (C_30) connected to the main microfluidic channel (C_1) by a second junction zone (Z_30), the first junction zone and the second junction zone being located opposite the trapping device, - The component comprising a first series of one or more lateral pillars (P_20) positioned at the level of the first junction zone (Z_20) and a second series of one or more lateral pillars (P_30) positioned at the level of the second junction zone (Z_30), each lateral pillar (P_20, P_30) of the first series and the second series also carrying a separate electrode intended to be placed at an electrical potential,- Each electrode being connected to said potentiostat to be brought to an electrical potential, said process being , characterized in thatIt consists of: - Selecting a zone of interest (Z) to monitor in the microfluidic component, said zone being chosen from the biological object trapping zone, the first junction zone and the second junction zone containing the surrounding fluidic medium, - Applying a first electrical potential to the electrode of the first central pillar, a second electrical potential to the electrode of the second central pillar, a third electrical potential to the electrode of each lateral pillar of the first series and a fourth electrical potential to the electrode of each lateral pillar of the second series, taking into account the selected zone of interest, - The first electrical potential, the second electrical potential, the third electrical potential and the fourth electrical potential being each chosen taking into account the selected zone of interest to monitor this zone of interest.

2. System for measuring electrical impedance through a biological object, comprising a microfluidic component and a potentiostat, characterized in thatThe microfluidic component comprises: - A support in which a main microfluidic channel (C_1) is formed, defining a path for the circulation of a fluid containing the biological object (O), - A trapping device positioned in the main microfluidic channel (C_1) on the circulation path of said biological object, this trapping device defining a trapping zone, - Said trapping device is composed of at least a first central pillar (P_1) and a second central pillar (P_2) positioned inside the main microfluidic channel, - The first central pillar carrying a first electrode and the second central pillar carrying a second electrode, - The support comprising a first lateral channel (C_20) connected to the main microfluidic channel (C_1) by a first junction zone (Z_20) and a second lateral channel (C_30) connected to the main microfluidic channel (C_1) by a second junction zone (Z_30),the first junction zone and the second junction zone being located opposite the trapping device, - The component comprising a first series of one or more lateral pillars (P_20) positioned at the first junction zone (Z_20) and a second series of one or more lateral pillars (P_30) positioned at the second junction zone (Z_30), each lateral pillar (P_20, P_30) of the first series and the second series also carrying a separate electrode intended to be held at an electrical potential, - Each electrode being connected to said potentiostat to be held at an electrical potential, - A processing unit of the system being configured to analyze measurement data generated by the implementation of the method defined in claim 1 and to determine properties of the trapped biological object (O) and / or its surrounding environment.

3. System according to claim 2, characterized in thatthe main microfluidic channel (C_1) extends lengthwise along a longitudinal axis (X) and in that it has a constant cross-section over at least part of its length, the first central pillar (P_1) and the second central pillar (P_2) being positioned symmetrically on either side of said longitudinal axis.

4. System according to claim 3, characterized in that the trapping device comprises a third central pillar and a fourth central pillar positioned symmetrically on either side of said longitudinal axis (X), the third central pillar being located on the same side with respect to the longitudinal axis (X) as the first central pillar and the fourth central pillar on the same side as the second central pillar.

5. System according to claim 4, characterized in that The third central pillar carries a third electrode and the fourth central pillar carries a fourth electrode.

6. System according to claim 4 or 5, characterized in that the trapping device includes a fifth central pillar, called the median pillar (P_3), positioned along the longitudinal axis (X), the median pillar carrying a fifth electrode, intended to be placed at a neutral electrical potential.

7. System according to any one of claims 2 to 6, characterized in that the central pillars (P_1, P_2, P_3) of the trapping device are positioned along an arc of a circle.

8. System according to any one of claims 2 to 7, characterized in that the central pillars (P_1, P_2, P_3) of the trapping device each have a circular cross-section.

9. System according to any one of claims 2 to 7, characterized in that The first central pillar (P_1) and the second central pillar (P_2) each have a kidney-shaped cross-section.

10. System according to claim 2, characterized in thatEach lateral pillar (P_20, P_30) has a triangular cross-section.

11. System according to claim 2, characterized in that Each lateral pillar (P_20, P_30) has a semicylindrical shape.

12. System according to any one of claims 2 to 11, characterized in that the support includes an intermediate layer (L_2) made of a doped silicon-type material, said intermediate layer (L_2) being configured to make each pillar (P_1, P_2, P_3, P_20, P_30).

13. System according to claim 12, characterized in that the intermediate layer (L_2) comprises a body made around said pillars, configured to be electrically insulating.

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