Holding apparatus for holding a microfluidic chip, and method for using a microfluidic chip

Abstract

The invention relates to a holding apparatus (1) for holding a microfluidic chip (2), the holding apparatus (1) comprising a chip carrier (3) for, in particular detachably, positioning a microfluidic chip (2) in order to feed a fluid, in particular oil, into a microfluidic channel system (8) of the microfluidic chip (2) via a fluid inlet (6) of the microfluidic chip (2). According to the invention, for an optimized application, the holding apparatus (1) comprises a fiber-optic pressure sensor (14) for measuring a fluid pressure of the fluid fed into the microfluidic channel system (8) when in use, and / or the holding apparatus (1) comprises a plurality of individually controllable heating elements (27) in order to controlledly heat the microfluidic chip (2) or the fluid when in use. The invention also relates to a method for using a microfluidic chip (2).

Description

[0001] Holding device for holding a microfluidic chip and method for using a microfluidic chip

[0002] The invention relates to a holding device for holding a microfluidic chip, wherein the holding device has a chip carrier for the, in particular detachable, arrangement of a microfluidic chip in order to supply a fluid, in particular oil, into a microfluidic channel system of the microfluidic chip via a fluid inlet of the microfluidic chip.

[0003] Furthermore, the invention relates to a method for using a microfluidic chip, wherein a microfluidic chip is arranged on a chip carrier of a holding device for holding the microfluidic chip, wherein a fluid, in particular oil, is supplied into a microfluidic channel system of the microfluidic chip via a fluid inlet of the microfluidic chip.

[0004] To investigate the flow behavior of a fluid in the rock of underground deposits, it is known to simulate the rock structure of the rock using a microfluidic chip, wherein a microfluidic channel system of the microfluidic chip is designed to correspond to the rock porosity or a rock channel system of the rock. For this purpose, it is usually provided that the microfluidic chip is held with a holding device and a fluid is introduced into the microfluidic channel system via a fluid inlet of the microfluidic chip in order to investigate the flow behavior of the fluid in the microfluidic channel system, usually under microscopic observation. For example, with a view to exploring oil extraction from the rock, oil can first be introduced into the microfluidic channel system in order to then investigate the possibility of extracting the oil from the rock by introducing water into the microfluidic channel system.The holding device typically comprises a chip carrier for holding the typically plate-shaped microfluidic chip. The microfluidic chip is typically designed to allow light to pass through it, allowing the flow behavior of the fluid in the microfluidic channel system to be observed with a microscope while light passes through the microfluidic chip.

[0005] This is where the invention comes in. The object of the invention is to provide a holding device of the type mentioned above, which enables an optimized application of a microfluidic chip, in particular an optimized investigation of the flow behavior of a fluid supplied to the microfluidic chip. A further object of the invention is to provide a method of the type mentioned above, which enables an optimized application of a microfluidic chip, in particular an optimized investigation of the flow behavior of a fluid supplied to the microfluidic chip.

[0006] The object is achieved according to the invention in that, in a holding device of the type mentioned at the outset, the holding device has a fiber optic pressure sensor in order to measure a fluid pressure of the fluid supplied into the microfluid channel system in the use state, and / or the holding device has a plurality of individually controllable heating elements in order to heat the microfluidic chip or the fluid in a controlled manner in the use state.

[0007] The invention is based on the idea of ​​simulating the behavior of a fluid in a rock using the microfluidic chip and a fluid added to the microfluidic channel system with precisely defined boundary conditions. A precise representation of a fluid pressure and / or a temperature of the fluid in the microfluidic channel system has proven particularly relevant for this purpose. However, a precise determination or setting of the fluid pressure and / or temperature of the fluid has proven difficult, particularly due to the typically very small volumes of microfluidic channels in the microfluidic channel system. This is particularly true for an investigation of the behavior of microfluidic flows of the fluid in the microfluidic channel system of the microfluidic chip. Accordingly, it is advantageous if the holding device is designed to enable a precise fluid pressure measurement and / or a precise setting of the temperature of the fluid in the microfluidic chip in an operational state.This can be achieved if the holding device has a fiber optic pressure sensor for measuring fluid pressure and / or a plurality of individually controllable, in particular adjustable, heating elements for heating the microfluidic chip or the fluid in the microfluidic channel system. The fiber optic pressure sensor enables fluid pressure measurement with high accuracy, in particular as explained below. The plurality of individually controllable, in particular separately controllable heating elements enable a homogeneous temperature to be set with high accuracy along the microfluidic chip or along the fluid in the microfluidic channel system. As a result, as a result of precisely known boundary conditions, the behavior of the fluid can be realistically simulated, reproduced and investigated. A meaningful fluid pressure measurement of a fluid in the microfluidic channel system has proven particularly difficult due to the generally small volumes of microfluidic channels in the microfluidic channel system orof a fluid introduced into them, has proven difficult to implement. In particular, a pressure measurement often leads to a change in the system to be measured in terms of the fluid present in the microfluidic channel system, so that an accurate and reliable pressure measurement is prevented or the system to be measured is impaired for an investigation. This can, for example, lead to microstructural, often microbiological, processes that are intended to take place in the microfluidic channels taking place in the area of ​​a pressure sensor. A relevant cause is often that conventional pressure sensors usually cause a dead volume that is many times the volume of the microfluidic channel system or its microfluidic channels. A typical volume of a microfluidic channel system, for example, is around 20 pl. Conventional pressure sensors usually have a dead volume of more than 200 pl.Typically, the dead volume is a volume introduced into a system to be measured by a pressure sensor or caused by the pressure measurement that influences the system to be measured. It has been shown that the aforementioned problem can be solved by using a fiber-optic pressure sensor to measure the fluid pressure in the microfluidic channel system, or by using a fiber-optic pressure sensor in the holding device for this purpose. This makes it possible to perform a fluid pressure measurement of the fluid with generally negligible interference with the measuring system from the fluid in the microfluidic channel system. A fiber-optic pressure sensor can be connected to the microfluidic chip as part of the holding device without significantly impairing the design of the microfluidic channel system. The fiber-optic pressure sensor can be coupled to the microfluidic chip or microfluidic chip, preferably with a negligible dead volume.This allows an application or an investigation of a fluid supplied to the microfluidic chip, in particular its behavior, usually flow behavior, to be optimized.

[0008] The microfluidic chip typically has a microfluidic channel system and a fluid inlet for supplying a fluid to the microfluidic channel system via the fluid inlet. A fluid located in the microfluidic channel system can be discharged from the microfluidic channel system via a fluid outlet of the microfluidic chip. The fluid inlet or fluid outlet is typically fluidically connected to the microfluidic channel system. The microfluidic channel system is generally connected to several fluidically connected fluid channels. In this way, rock porosity or a rock channel system, through which a fluid can be conducted, can be simulated with the microfluidic chip or the microfluidic channel system. A microfluidic channel system typically has a volume for accommodating fluid of between 5 pl and 100 pl, in particular between 10 pl and 50 pl, preferably between 15 pl and 30 pl, in particular approximately 20 pl.The diameter of the fluid channels is generally less than 1000 pm, in particular less than 500 pm, preferably less than 100 pm, particularly preferably less than 50 pm, particularly preferably less than 10 pm, especially preferably less than 1 pm. The microfluidic chip is generally plate-shaped. The microfluidic chip typically has a length and a width of less than 10 cm, in particular less than 8 cm. The height of the microfluidic chip is typically orthogonal to a length and width of the microfluidic chip, wherein the height is generally less than both the length and the width of the microfluidic chip.

[0009] The chip carrier is typically designed to arrange or fix a microfluidic chip, in particular detachably, on the holding device. The holding device can have a fluid supply device with which a fluid can be supplied to a microfluidic chip arranged with the chip carrier, typically via a fluid inlet of the microfluidic chip.

[0010] It is practical if the fiber optic pressure sensor is coupled to the chip carrier in such a way that the fiber optic pressure sensor, in the use state, is connected to the microfluidic channel system, in particular in a fluid pressure transmitting manner, in order to measure a fluid pressure of the fluid supplied into the microfluidic channel system.

[0011] Typically, the microfluidic chip with the chip carrier can be arranged in an imaginary arrangement plane for establishing the use state, wherein the arrangement plane is oriented parallel to a longitudinal extent and a width extent of the microfluidic chip. An observation line of sight along which the microfluidic chip is usually observed in the use state is generally oriented transversely, in particular orthogonally, to the arrangement plane. The microfluidic chip is typically designed to allow light to pass through it, in particular opposite to the observation line. Typically, the microfluidic chip has two light-transmissive or transparent cover surfaces, usually formed with or from quartz glass, between which the microfluidic channel structure is formed. The cover surfaces are each oriented parallel to a longitudinal extent and a width extent of the microfluidic chip.

[0012] The operational state usually refers to a state when a microfluidic chip with the chip carrier is arranged on the holding device in order to examine a fluid located in a microfluidic channel system of the fluid or a fluid to be supplied to the microfluidic channel system, in particular its behavior.

[0013] The fiber optic pressure sensor typically has a measuring head for measuring a fluid pressure acting on the measuring head in the use state with the fiber optic pressure sensor. For this purpose, the fiber optic pressure sensor, in particular the measuring head, usually has a measuring surface for measuring a fluid pressure acting on the measuring surface with the fiber optic pressure sensor, usually through deformation, in particular elastic deformation, of the measuring surface. The measuring head is usually arranged in such a way, in particular coupled to the chip carrier, that the measuring head is in fluid pressure-transmitting communication with a fluid supplied to the microfluidic channel system in the use state. The measuring head is usually arranged in such a way that it is guided essentially from a lateral direction to the chip carrier or, in the use state, to the microfluidic chip and coupled to it. This applies in particular in a plan view of the arrangement plane.The lateral direction is usually oriented essentially parallel to the arrangement direction.

[0014] The fiber optic pressure sensor can be coupled to the chip carrier in such a way that, in the use state, the measuring surface is connected to the microfluidic chip, in particular the microfluidic channel system, in such a way that it contacts the fluid, in particular connecting it to the microfluidic channel system, in order to measure the fluid pressure of the fluid with the measuring surface.

[0015] For high accuracy, it is advantageous if the chip carrier has a fluid transfer channel, which, in the use state, is fluidly connected to the microfluidic channel system of the microfluidic chip, in particular adjoins it, wherein the measuring surface of the fiber optic pressure sensor is connected to the fluid transfer channel for measuring a fluid pressure of a fluid in the fluid transfer channel. In this case, it is usually provided that a fluid supplied to the microfluidic channel system fills the fluid transfer channel. The measuring surface is usually connected to the fluid transfer channel for fluid pressure measurement. In this way, the fluid pressure of the fluid in the microfluidic channel system can be measured by measuring the fluid pressure of the fluid in the fluid transfer channel.It is advantageous if the fluid transmission channel has a volume for receiving the fluid that is less than 10 pl, in particular less than 5 pl, preferably less than 1 pl, particularly preferably less than 0.5 pl. This allows a dead volume of the fluid pressure measurement or the fiber optic pressure sensor to be kept particularly small.

[0016] Typically, the chip carrier has a supply channel for supplying fluid to the fluid inlet of the microfluidic chip via the supply channel when in use. It is expedient if the supply channel is fluidically connected to the fluid inlet when in use, in particular if it adjoins it. It is advantageous if the measuring surface or fluid transfer channel is arranged such that, when in use, it adjoins a section of the microfluidic chip in which the fluid inlet of the microfluidic chip is located. It is practical if the fluid transfer channel adjoins the supply channel. Typically, this allows fluid supplied to the supply channel to be directed into the fluid transfer channel for fluid pressure measurement.

[0017] It is expedient if the holding device has a supply valve so that, in the use state, a supply of fluid to the fluid inlet can be controlled, in particular regulated, by controlling, in particular regulating, the supply valve. The chip carrier typically has an inlet connection which, in the use state, is fluidly connected to the fluid inlet of the microfluidic chip in order to supply fluid to the fluid inlet via the inlet connection. For this purpose, the supply channel can be formed as part of the inlet connection. The supply valve can be connected to the inlet connection and can be designed to control, in particular regulate, a flow of fluid through the inlet connection in the use state.For example, the holding device can have a supply line which is fluidically connected to the inlet connection, wherein the supply valve is arranged between the supply line and the inlet connection in order to control, in particular regulate, an inflow of fluid from the supply line to the inlet connection with the supply valve. The holding device can have a discharge valve so that, in the use state, a discharge of the fluid from the fluid outlet can be controlled, in particular regulated, by controlling, in particular regulating, the discharge valve. The chip carrier usually has an outlet connection which, in the use state, is fluidically connected to the fluid outlet of the microfluidic chip in order to discharge fluid from the fluid outlet via the outlet connection. The discharge valve can be connected to the outlet connection and can be designed to control, in particular regulate, a flow of fluid through the outlet connection in the use state.For example, the holding device can have a discharge line that is fluidically connected to the output connection, wherein the supply valve is arranged between the discharge line and the output connection in order to control, in particular regulate, an outflow of fluid from the output connection into the discharge line with the discharge valve. The holding device can have one or more operating devices, for example operating levers, with which the supply valve and / or discharge valve can be controlled, in particular regulated, in particular separately from one another. The holding device can expediently have an electronic control unit that is designed to control, in particular regulate, the supply valve or discharge valve.

[0018] It is advantageous if the chip carrier and the measuring head are detachably connected to one another. It has proven useful if the chip carrier and the measuring head are connected to one another in a form-fitting and / or force-fitting manner, usually detachably. Although less preferred, the measuring head and the chip carrier can be connected to one another in a materially bonded manner. It is advantageous if the chip carrier has a measuring head receptacle and the measuring head has an outer casing whose shape corresponds to that of the measuring head receptacle, wherein the outer casing is inserted into the measuring head receptacle in a form-fitting manner to connect the chip carrier and the measuring head. The measuring head can be connected to the chip carrier in a form-fitting and / or force-fitting manner, for example with a screw connection, opposite to an insertion direction in which the measuring head is inserted into the measuring head receptacle.For this purpose, the measuring head can have a thread that corresponds in shape to a thread of the measuring head mount, in order to connect the measuring head and the measuring head mount by screwing the threads together. The thread can be formed as part of a screw body of the measuring head.

[0019] It is advantageous if the chip carrier and the measuring head of the fiber optic pressure sensor are connected to one another in a fluid-tight manner, in particular in a liquid-tight and / or gas-tight manner. For this purpose, the measuring head can have a sealing element. The sealing element can be formed with, in particular from, polytetrafluoroethylene (PTFE). For a robust, fluid-tight connection, it is advantageous if the chip carrier and the measuring head are connected to one another in such a way that a press connection is created between the sealing element and the chip carrier, in particular the measuring head holder. It is advantageous if the sealing element surrounds the measuring head circumferentially or forms a circumference of the measuring head. The sealing element can be part of the outer casing. It has proven useful if the outer casing, in particular the sealing element, is conical in shape, at least in sections.It is advantageous if, in an insertion direction in which the measuring head is inserted into the measuring head receptacle, a support element, usually a support ring, is arranged in front of at least one segment of the sealing element, so that the sealing element is pressed against the support element when the measuring head is inserted into the measuring head receptacle. Several such sealing elements can expediently be provided.

[0020] For high measurement accuracy, it is advantageous if the fiber optic pressure sensor has an optical waveguide, wherein the optical waveguide is coupled to a measuring surface of the fiber optic pressure sensor, such that a change in a fluid pressure acting on the measuring surface corresponds to a change in an optical signal line, in particular a change in an interference signal, of a lightwave signal coupled into the optical waveguide in order to measure the fluid pressure. The change in the optical signal line can, for example, be a change in the optical path length of the lightwave signal or a change in an interference signal formed by interference of the lightwave signal. The measuring surface can be part of the optical waveguide, in particular a first end piece of the optical waveguide. The first end piece can be formed as part of the measuring head.The measuring surface can be elastically deformable so that, for fluid pressure measurement, the fluid pressure acting on the measuring surface causes an elastic deformation of the measuring surface. For this purpose, the measuring surface can expediently be an elastically deformable membrane. The measuring surface can be coupled to a mirror element so that an elastic deformation of the measuring surface corresponds to a displacement of the mirror element. For this purpose, an inner side of the measuring surface, in particular of the membrane, can be a mirror or be connected to a mirror. In this way, by displacement of the mirror element, an optical path length of a lightwave signal reflected by the mirror element can change in order to measure the fluid pressure. It is advantageous if the displacement of the mirror causes an interference signal, formed by interference with a lightwave signal coupled into the optical fiber, in order to measure the fluid pressure.

[0021] For high accuracy, it is advantageous if the measuring surface and the optical fiber are coupled to one another via an optical resonator in order to effect a change in the optical signal transmission. The optical resonator is usually formed with several mirrors in order to effect multiple reflections of a light wave signal coupled into the optical fiber between the mirror elements, so that the light wave signal forms an interference signal in order to measure the fluid pressure by measuring the interference signal. For this purpose, at least one of the mirrors is usually partially transparent to the light wave signal. Another of the mirrors can be the aforementioned mirror element. For example, a partially transparent mirror can be arranged in front of the mirror element in the direction in which the light wave is coupled into the optical fiber in order to generate multiple reflections between the mirror element and the partially transparent mirror to form an interference signal.The mirror element can be designed to be entirely reflective. It is preferred if the optical resonator is a Fabry-Perot resonator. Typically, the interference signal is redirected along the optical waveguide opposite to the lightwave coupling direction, particularly for detection by a detector.

[0022] The optical wave coupling direction usually refers to the direction along the optical waveguide in which the optical wave signal is coupled into the optical waveguide using a light emission source.

[0023] In a practical manner, the fluid pressure can be measured interferometrically, particularly in the manner described above. Preferably, the fiber optic pressure sensor comprises an interferometer for measuring the fluid pressure. For example, the interferometer can be a Fabry-Perot interferometer.

[0024] The fiber optic pressure sensor can have a detector for measuring a change in the optical signal transmission, in particular a change in an interference signal, of a lightwave signal coupled into the optical fiber. The detector is typically coupled to a second end piece of the optical fiber in order to measure a lightwave signal, in particular an interference signal, conducted via the optical fiber to the second end piece. The lightwave signal is typically guided to the second end piece or detector in the opposite direction to the lightwave coupling direction. The second end piece is generally an end piece of the optical fiber facing away from the measuring surface. The detector can be a photodetector, for example. In particular, the detector can measure a change in the optical path length, in particular the aforementioned change, or an interference signal.The detector is typically connected to an electronic evaluation unit for data transmission. The electronic evaluation unit can be designed for data collection and / or further processing.

[0025] The fiber optic pressure sensor typically has a light emission source coupled to the optical fiber in such a way that a light wave signal generated by the light emission source can be coupled into the optical fiber. For this purpose, the light emission source is typically coupled to a second end piece, in particular the aforementioned second end piece, of the optical fiber. The light wave signal can be an electromagnetic wave, in particular in the electromagnetic UV wavelength spectrum, in the electromagnetic wavelength spectrum visible to humans, or in the electromagnetic infrared wavelength spectrum. Accordingly, the optical fiber is typically configured to transmit such a light wave signal, and the detector is configured to detect such a light wave signal.The detector and the light emission source can be connected to the second end piece of the optical waveguide, for example, by an optical coupler, such as an optical splitter.

[0026] A compact design is possible if the first end piece of the optical fiber is formed as part of the measuring head. The measuring head can have a fixing body arranged on the first end piece of the optical fiber, typically by means of a force-fitting, form-fitting, and / or material-fitting connection. The fixing body can enclose the first end piece circumferentially, for example, in a tubular manner. The sealing element and / or the support element are typically arranged on the fixing body. A robust design can be achieved if the sealing element and the support element are arranged on the fixing body in a force-fitting manner, for example, clamped to the fixing body.

[0027] For accurate fluid pressure measurement, it is advantageous if the dead volume of the fluid pressure measurement with the fiber optic pressure sensor is less than 10 pl, in particular less than 5 pl, preferably less than 1 pl, particularly preferably less than 0.5 pl. The fiber optic pressure sensor is typically coupled to the microfluidic chip or microfluidic channel system with such a dead volume for fluid pressure measurement.

[0028] It is practical if the chip carrier has an adapter holder detachably connected to a chip carrier body of the chip carrier, in order to connect the microfluidic chip to the chip carrier body by means of the adapter holder. The adapter holder can be designed for a form-fitting and / or force-fitting detachable connection to a microfluidic chip. The adapter holder can have a chip receptacle configured to correspond to the size and / or shape of a microfluidic chip, to which the microfluidic chip can be connected in a form-fitting and / or force-fitting manner. The chip receptacle can be designed with a receptacle frame.The chip holder can expediently have a fixing element, in particular one that can be detachably connected to the holding frame. For arranging the microfluidic chip on the holding frame, the microfluidic chip can be arranged between the holding frame and the fixing element, so that the microfluidic chip can be connected to the adapter holder in a form-fitting and / or force-fitting manner by fastening the fixing element to the holding frame. High practical application can be achieved if the adapter holder is designed to correspond to the shape and / or size of a class of microfluidic chips of the same shape and / or size, in order to connect different classes of microfluidic chips to the chip carrier body using different adapter holders. The holding device can have a plurality of adapter holders, wherein different adapter holders are designed for connection to different classes of microfluidic chips.A class of microfluidic chips typically defines microfluidic chips of the same shape and / or size. Microfluidic chips of different classes typically have different shapes and / or sizes.

[0029] It is advantageous if the holding device has a plurality of individually controllable, in particular adjustable, heating elements in order to heat the microfluidic chip in a controlled, in particular regulated, manner in the use state. This allows a temperature of the microfluidic chip or of a fluid supplied to the microfluidic chip to be set, in particular controlled, preferably regulated. The heating elements are usually arranged such that, in the use state, the microfluidic chip can be heated from different sides with respect to the microfluidic chip using the heating elements. The heating elements are usually arranged such that, in the use state, a heating element is present on each side of the microfluidic chip next to the microfluidic chip, wherein, in particular, each side is assigned its own heating element. An arrangement of the heating elements refers in particular to a view orthogonal to the arrangement plane.An arrangement of the heating elements with respect to a microfluidic chip in the use state can apply analogously to an arrangement of the heating elements with respect to the chip carrier. Typically, at least two heating elements are arranged such that, in the use state, they are arranged on opposite sides of the microfluidic chip. For this purpose, the at least two heating elements are usually arranged on opposite sides of the chip carrier. The heating elements are usually arranged laterally next to the microfluidic chip or the chip carrier in a plan view of the arrangement plane. As a result, an observation line of sight along which the microfluidic chip is usually observed in the use state is not obscured. The arrangement plane is usually aligned parallel to a longitudinal extension and a width extension of the microfluidic chip. The observation line of sight is usually oriented transversely, in particular orthogonally, to the arrangement plane.It is advantageous if, in a plan view of the arrangement plane, a plurality of heating elements are arranged circumferentially around the chip carrier or, in the use state, circumferentially around the microfluidic chip. Preferably, more than three, in particular between three and five, individually controllable, in particular adjustable, heating elements are provided. The heating elements are usually arranged such that, in the use state, the microfluidic chip can be heated from a lower side. Alternatively or cumulatively, it can be advantageous if the heating elements are arranged such that, in the use state, the microfluidic chip can be heated from an upper side. The heating elements can be designed as electrical resistance heaters. The heating elements are usually plate-shaped, in particular as heating foils. The heating elements can advantageously be designed or arranged to heat the microfluidic chip orto heat the fluid to a temperature of more than 100 °C, in particular more than 130 °C, preferably between 25 °C and 200 °C.

[0030] It is advantageous if the holding device has a fan for generating an air flow in order to distribute heat generated by the heating elements with the air flow along the microfluidic chip when in use. This makes it possible to achieve a homogeneous temperature distribution on the microfluidic chip or in a fluid supplied to it. Typically, the fan is individually controllable, in particular adjustable. In particular, it is separate from the heating elements. Preferably, several fans are provided, each of which is individually controllable, in particular adjustable. In particular, a temperature of the microfluidic chip or of a fluid supplied to it can be adjusted with high precision by means of individually controllable, in particular adjustable, heating elements and at least one, preferably several individually controllable, in particular adjustable, fans.It is advantageous if the holding device has an electronic control device which is designed to individually control, in particular to regulate, the heating elements and / or the fans.

[0031] Individual control of the heating elements or fans refers, in particular, to controlling the heating elements so that the heating intensity of the heating elements can be controlled separately from one another or the air acceleration can be controlled separately from one another using the fans. This applies analogously to regulating the heating elements or fans. This can be implemented using a common control device or multiple control devices of the holding device. The chip carrier can expediently have one or more valves that are connected to the fan in an airflow-conducting manner in order to direct an air flow generated by the fan via the valves to the microfluidic chip. For this purpose, the valves can be coupled to the fan via air supply lines.For high accuracy, it is advantageous to couple different valves to different fans, allowing airflow generated by different fans to be directed to the microfluidic chip via different valves. Typically, each fan is assigned at least one separate valve for this purpose.

[0032] Precise temperature control can be achieved if the holding device has one or more thermocouples in order to control, in particular regulate, the heating elements and / or the fan depending on a temperature measurement with the thermocouples. The thermocouples are usually arranged laterally next to the chip carrier in a plan view of the arrangement plane or laterally next to the microfluidic chip in the use state. Typically, at least two thermocouples are arranged such that they are arranged on opposite sides of the microfluidic chip in the use state. For this purpose, the at least two heating elements are usually arranged on opposite sides of the chip carrier. Preferably, at least four thermocouples are provided, which are arranged on different sides of the microfluidic chip in the use state in a plan view of the arrangement plane.

[0033] The chip carrier can be formed with a holding frame to which the microfluidic chip can be connected in a form-fitting and / or force-fitting manner, for example by means of a screw connection and / or clamp connection. The chip carrier can have a fastening element, which can be connected, in particular, detachably to the holding frame. For arranging the microfluidic chip on the holding device, the microfluidic chip can be arranged between the holding frame and the fastening element, so that the microfluidic chip can be connected to the chip carrier in a form-fitting and / or force-fitting manner by fastening the fastening element to the holding frame. The fastening element can be a frame structure. In this way, the microfluidic chip can be arranged with the chip carrier in the arrangement plane.The microfluidic chip can be arranged with the chip carrier on the holding device in such a way that a central region of the microfluidic chip is uncovered in the observation direction in order to observe or examine the central region. The observation direction is usually a view of the microfluidic chip from above, generally substantially orthogonal to the arrangement direction. The holding device is usually designed such that, in the use state, the microfluidic chip can be irradiated with light, in particular passed through, from an underside, in particular substantially opposite to the observation direction. For this purpose, the holding device can have a light source or be designed such that a light source can be arranged beneath the microfluidic chip for irradiating, in particular passing through, the microfluidic chip.

[0034] Advantageously, an examination arrangement for examining the behavior of a fluid can be provided, wherein the examination arrangement comprises a holding device and a microfluidic chip, wherein the microfluidic chip is arranged, in particular detachably, on the holding device with a chip carrier. The holding device and the microfluidic chip can be designed as described in this document.

[0035] The further object of the invention is achieved by a method of the type mentioned above for using a microfluidic chip, in particular for investigating the flow behavior of a fluid, when a fluid pressure of the fluid supplied to the microfluidic channel system is measured using a fiber-optic pressure sensor and / or the microfluidic chip or the fluid is heated using a plurality of individually controllable heating elements. The method can be implemented, in particular, using an aforementioned holding device. The fiber-optic pressure sensor can be used to determine the fluid pressure in the microfluidic channel system with high accuracy. The fiber-optic pressure sensor can expediently be connected to the microfluidic channel system for fluid pressure measurement. By individually controlling, in particular regulating, the heating elements, a temperature of the microfluidic chip or of the fluid in the microfluidic channel system can be adjusted with high accuracy.In this way, boundary conditions for investigating fluid behavior, particularly its flow behavior, can be defined with high precision. Accordingly, investigations can be conducted with high reliability. This is especially true for simulating or replicating the behavior of a fluid in a rock. Preferably, the microfluidic chip, particularly its microfluidic channel system, is used to replicate a channel system, particularly a pore system, of a rock.

[0036] It is understood that the method for using a microfluidic chip can be designed according to the features and effects described in this document in the context of a holding device, in particular above. The same applies to the holding device with regard to the method. The fluid can be liquid and / or gaseous. It is advantageous if the fluid is formed with, in particular from, oil, in particular petroleum, and / or with, in particular from, natural gas.

[0037] It is advantageous if the microfluidic chip is heated with heating elements, with a fan generating an airflow to distribute the heat generated by the heating elements along the microfluidic chip. The heating elements and the fan are individually controlled, in particular regulated, from each other. In this way, the temperature of the microfluidic chip or fluid can be adjusted, in particular controlled, preferably regulated, with high precision.

[0038] Preferably, the heating elements and the fan are controlled, in particular regulated, depending on a temperature measured by several thermocouples.

[0039] Further features, advantages, and effects of the invention will become apparent from the following description of an exemplary embodiment. The drawings, to which reference is made, show:

[0040] Fig. 1 is an exploded view of a holding device for holding a microfluidic chip in a front view;

[0041] Fig. 2 shows the holding device in a view from above;

[0042] Fig. 3 is an exploded view of the holding device from the rear;

[0043] Fig. 4 is a representation of a portion of a chip carrier of the holding device with a fiber optic pressure sensor coupled to the chip carrier;

[0044] Fig. 5 to Fig. 7 show partial views of the fiber optic pressure sensor;

[0045] Fig. 8 is a cross-sectional view of the holding device in a view from below.

[0046] Fig. 1 shows a schematic representation of a holding device 1 for holding a microfluidic chip 2 in an exploded view, as well as a microfluidic chip 2. The microfluidic chip 2 can be detachably arranged, usually fixed, on the holding device 1 using a chip carrier 3. The chip carrier 3 has a holding frame 4, to which the microfluidic chip 2 can be connected in a form-fitting and / or force-fitting manner. For this purpose, the chip carrier 3 has a fastening element 5 that can be detachably connected to the holding frame 4 and can be designed as a frame structure. In order to arrange the microfluidic chip 2 on the holding device 1, the microfluidic chip 2 can be arranged between the holding frame 4 and the fastening element 5, such that the microfluidic chip 2 can be connected to the chip carrier 3 in a form-fitting and / or force-fitting manner by fastening the fastening element 5 to the holding frame 4.In this way, the microfluidic chip 2 can be arranged with the chip carrier 3 in an imaginary arrangement plane, wherein a length and a width of the microfluidic chip 2 are generally oriented parallel to the arrangement plane. The microfluidic chip 2 can be arranged with the chip carrier 3 on the holding device 1 such that, in an observation direction B, a central region of the microfluidic chip 2 is uncovered in order to observe or examine the central region. The observation direction B is usually a view from above onto the microfluidic chip 2, usually essentially orthogonal to the arrangement direction. Fig. 2 shows a schematic representation of the holding device 1 of Fig. 1 in a view from above or a view from the observation direction B.

[0047] The microfluidic chip 2 has a microfluidic channel system 8, a fluid inlet 6, and a fluid outlet 7. In use, the microfluidic channel system 8 is introduced via the fluid inlet 6 and discharged from the microfluidic channel system 8 via the fluid outlet 7. The microfluidic channel system 8 typically corresponds to a channel structure or pore structure of a rock.

[0048] Fig. 3 shows a schematic representation of the holding device 1 of Fig. 1 in an exploded view viewed obliquely from the rear. The holding device 1 has a supply valve 9 such that, in the use state, with control, in particular regulation, of the supply valve 9, a supply of fluid to the fluid inlet 6 can be controlled, in particular regulated. The holding device 1 has a discharge valve 10 such that, in the use state, with control, in particular regulation, of the discharge valve 10, a discharge of the fluid from the fluid outlet 7 can be controlled, in particular regulated. The holding device can have one or more operating levers 11 with which the supply valve 9 and discharge valve 10 can be controlled, in particular separately from one another.The chip carrier 3 typically has an inlet port 12 which, in the use state, is fluidly connected to the fluid inlet 6 of the microfluidic chip 2 in order to supply fluid to the fluid inlet 6 via the inlet port 12. This is typically done via a supply channel 13 of the inlet port 12 which, in the use state, is fluidly connected to the fluid inlet 6. The supply valve 9 can be designed to control, in particular to regulate, a flow of fluid through the inlet port 12 in the use state. The chip carrier 3 typically has an outlet port which, in the use state, is fluidly connected to the fluid outlet 7 of the microfluidic chip 2 in order to discharge fluid from the fluid outlet 7 via the outlet port. The discharge valve 10 can be designed to control, in particular to regulate, a flow of fluid through the outlet port in the use state.

[0049] The holding device has a fiber optic pressure sensor 14 for measuring a fluid pressure of the fluid supplied to the microfluidic channel system 8 in the use state. The fiber optic pressure sensor has a measuring head 15 having a measuring surface 16 for measuring a fluid pressure acting on the measuring surface 16. The fiber optic pressure sensor 14 has an optical fiber 17, wherein a first end piece 18 of the optical fiber 17 is formed as part of the measuring head 15. The measuring head 15 is coupled to the chip carrier 3 in such a way that a fluid supplied via the input connection 12 in the use state acts to transmit fluid pressure to the measuring surface 16. Fig. 4 shows a schematic representation of a region of the chip carrier 3 of Fig. 1, in which the measuring head 15 of the fiber optic pressure sensor 14 is coupled to the chip carrier 3.The chip carrier 3 has a fluid transfer channel 20, which is fluidically connected to the supply channel 13 of the input port 12. The measuring surface 16 is connected to the fluid transfer channel 20 for fluid pressure measurement. In the operating state, the supply channel 13 is typically connected to the fluid inlet 6 of the microfluidic chip 2.

[0050] The chip carrier 3 has a measuring head receptacle 21, which is designed to correspond in shape to an outer casing of the measuring head 15, wherein the outer casing is positively inserted into the measuring head receptacle 21 in order to connect the chip carrier 3 and the measuring head 15. The measuring head 15 has a sealing element 22, which forms part of the outer casing in order to implement a fluid-tight connection between the measuring head receptacle 21 and the measuring head 15. The sealing element 22 runs circumferentially around the first end piece 18 of the optical waveguide 17 and is conical in sections. It is advantageous if the sealing element 22 is formed from polytetrafluoroethylene (PTFE). The measuring head 15 has a tubular fixing body 23, which is arranged on the first end piece 18 of the optical waveguide 17 by means of a force-fitting, form-fitting and / or material-fitting connection. The fixing body 23 can expediently enclose the first end piece 18 circumferentially.A support element 24, typically a support ring, is arranged upstream of a segment of the sealing element 22 in an insertion direction in which the measuring head 15 is inserted into the measuring head receptacle 21, so that the sealing element 22 is pressed against the support element 24 when the measuring head 15 is inserted into the measuring head receptacle 21. The sealing element 22 and the support element 24 are arranged on the fixing body 23. It is practical if the sealing element 22 is clamped to the fixing body 23 with the support element 24. The measuring head 15 can have a screw body 25 with a thread 26, which is designed to correspond in shape to a thread of the measuring head receptacle 21, in order to connect the measuring head 15 by screwing the threads together.

[0051] The first end piece 18 is coupled to the measuring surface 16, so that a fluid pressure acting on the measuring surface 16 or a change in the fluid pressure corresponds to a change in an optical signal line, in particular an interference signal, of a lightwave signal coupled into the optical fiber 17. The measuring surface 16 is preferably designed as an elastically deformable membrane. The measuring surface 16 can be coupled to a mirror element, so that an elastic deformation of the measuring surface 16 corresponds to a displacement of the mirror element. The mirror element is preferably designed as part of a measuring interferometer of the fiber optic pressure sensor 14, wherein an interference signal is formed with the lightwave signal in order to measure the fluid pressure interferometrically, wherein a displacement of the mirror element corresponds to a change in the interference signal.Typically, multiple reflections of the lightwave signal are formed between the mirror element and a mirror to generate the interference signal. This can be implemented using a Fabry-Perot resonator. The mirror is typically partially transparent to the lightwave signal in order to couple out the interference signal for measurement. Typically, the interference signal is reflected back along the optical waveguide 17 in order to measure the interference signal with a detector, usually a photodetector, which is connected to a second end piece 19 of the optical waveguide 17. The second end piece 19 is typically coupled to a light emission source, usually a laser, for coupling in the lightwave signal. The detector and the light emission source can be connected to the optical waveguide 17, for example, using an optical coupler. In Fig. 5 to Fig.7 shows a detail of the fiber optic sensor of the holding device 1 of Fig. 1.

[0052] Fig. 8 shows a schematic cross-sectional view of the holding device 1 of Fig. 1 in a view from below. The holding device 1 has a plurality of individually controllable, in particular adjustable, heating elements 27 in order to heat the microfluidic chip 2 in a controlled, in particular regulated, manner in the use state. The heating elements 27 are arranged orthogonally to the arrangement plane next to the microfluidic chip 2, so that the microfluidic chip 2 can be heated from different sides with respect to the microfluidic chip 2 using the heating elements 27. Preferably, a heating element is present on each side of the microfluidic chip 2 next to the microfluidic chip 2, with each side being assigned its own heating element. Because the heating elements 27 are individually controllable, i.e., separately from one another, in particular adjustable, a temperature of the microfluidic chip 2 or of the fluid supplied to the microfluidic channel system 8 can be adjusted with high precision.The holding device 1 can have a fan 28 for generating an air flow in order to distribute heat generated by the heating elements 27 along the microfluidic chip 2 with the air flow during use. This ensures a particularly pronounced homogeneity of a temperature distribution along the microfluidic chip 2 or in a fluid supplied thereto. The holding device 1 can have one or more thermocouples in order to control, in particular regulate, the heating elements 27 and / or the fan 28 depending on a temperature measured with the thermocouples.

[0053] If the holding device 1 has a fiber-optic pressure sensor 14 for measuring fluid pressure and / or a plurality of individually controllable heating elements 27 for heating the microfluidic chip 2 or the fluid in the microfluidic channel system 8, a pressure and / or a temperature of the fluid in the microfluidic channel system 8 can be represented with high accuracy. This allows the behavior, in particular the flow behavior, of the fluid to be realistically simulated or recreated and investigated. This enables an optimized application of the holding device 1 or the microfluidic chip 2, in particular for predicting the behavior, in particular the flow behavior, of a fluid in a rock.

Claims

Patent claims 1. Holding device (1) for holding a microfluidic chip (2), wherein the holding device (1) has a chip carrier (3) for the, in particular detachable, arrangement of a microfluidic chip (2) in order to supply a fluid, in particular oil, into a microfluidic channel system (8) of the microfluidic chip (2) via a fluid inlet (6) of the microfluidic chip (2), characterized in that the holding device (1) has a fiber optic pressure sensor (14) in order to measure a fluid pressure of the fluid supplied to the microfluidic channel system (8) in the operating state, and / or the Holding device (1) has several individually controllable heating elements (27) in order to heat the microfluidic chip (2) or the fluid in a controlled manner during operation.

2. Holding device (1) according to claim 1 , characterized in that the fiber optic pressure sensor (14) is coupled to the chip carrier (3) in such a way that the fiber optic pressure sensor (14) is in contact with the microfluidic channel system (8) in the operating state in order to measure a fluid pressure of the fluid supplied to the microfluidic channel system (8).

3. Holding device (1) according to claim 1 or 2, characterized in that the chip carrier (3) has a fluid transfer channel (20) which, in the operating state, fluidly connects the fluid transfer channel (20) to the microfluidic channel system (8) of the microfluidic chip (2), wherein a measuring surface (16) of the fiber optic pressure sensor (14) for measuring the fluid pressure is connected to the fluid transfer channel (20).

4. Holding device (1) according to one of claims 1 to 3, characterized in that the chip carrier (3) and a measuring head (15) of the fiber optic pressure sensor (14) are fluid-tightly connected to each other.

5. Holding device (1) according to claim 4, characterized in that the measuring head (15) has a sealing element (22), preferably made of polytetrafluoroethylene, to connect the chip carrier (3) and the measuring head (15) together in a fluid-tight manner.

6. Holding device (1) according to one of claims 1 to 5, characterized in that the chip carrier (3) and a measuring head (15) of the fiber optic pressure sensor (14) are positively and / or force-fit connected to each other.

7. Holding device (1) according to claim 6, characterized in that the chip carrier (3) has a measuring head receptacle (21), preferably conical, and the measuring head (15) has an outer shell corresponding in form to the measuring head receptacle (21), wherein the outer shell is positively inserted into the measuring head receptacle (21) for connecting the chip carrier (3) and the measuring head (15).

8. Holding device (1) according to one of claims 1 to 7, characterized in that the fiber optic pressure sensor (14) has an optical waveguide (17), wherein the optical waveguide (17) is coupled to a measuring surface (16) of the fiber optic pressure sensor (14), such that a fluid pressure acting on the measuring surface (16) corresponds to a change in an optical signal line, in particular a change in an interference signal, of a light wave signal coupled into the optical waveguide (17) in order to measure the fluid pressure.

9. Holding device (1) according to claim 8, characterized in that the measuring surface (16) and the optical waveguide (17) are coupled via an optical resonator to effect a change in the optical signal transmission.

10. Holding device (1) according to one of claims 1 to 9, characterized in that the chip carrier (3) has an adapter holder detachably connected to a chip carrier body of the chip carrier (3) in order to connect the fluid microchip to the chip carrier body by means of the adapter holder, wherein the adapter holder is designed to correspond in shape to a shape and / or size of a class of fluid microchips in order to connect different classes of fluid microchips with different adapter holders to the chip carrier body.

11. Holding device (1) according to one of claims 1 to 10, characterized in that the holding device (1) has a fan (28) for generating an airflow in order to distribute heat generated with the heating elements (27) along the microfluidic chip (2) with the airflow in the operating state.

12. Holding device (1) according to one of claims 1 to 11, characterized in that the holding device (1) has one or more thermocouples to carry out control, in particular regulation, of the heating elements (27) and / or optionally of the fan (28) depending on a temperature measurement with the thermocouples.

13. Investigation arrangement for investigating the behavior of a fluid, wherein the investigation arrangement comprises a holding device (1) and a microfluidic chip (2), wherein the microfluidic chip (2) is arranged on the holding device (1) with a chip carrier (3), in particular detachably, characterized in that the holding device (1) is designed according to one of claims 1 to 12.

14. Method for using a microfluidic chip (2), in particular for investigating the flow behavior of a fluid, wherein a microfluidic chip (2) is arranged on a chip carrier (3) of a holding device (1), in particular a holding device (1) according to one of claims 1 to 13, for holding the microfluidic chip (2), wherein a fluid, in particular oil, is supplied to a microfluidic channel system (8) of the microfluidic chip (2) via a fluid inlet (6), characterized in that a fluid pressure of the fluid supplied to the microfluidic channel system (8) is measured with a fiber optic pressure sensor (14) and / or the microfluidic chip (2) or the fluid is heated with several individually controllable heating elements (27).

15. Method according to claim 14, characterized in that an airflow is generated by a fan (28) to distribute heat generated by the heating elements (27) along the fluid microchip, wherein the heating elements (27) and the fan (28) are individually controlled, in particular regulated, from one another.

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