Immersion sensor for electrochemical measurements and method for manufacturing an immersion sensor

Abstract

Immersion sensor (100) with multiple electrodes (130, 150, 155). The immersion sensor (100) is designed so that its distal end (191) can be immersed in an assay (90). The immersion sensor (100) can be connected to a measuring system (40) to perform an electrochemical measurement.

Description

TECHNICAL FIELD

[0001] Various examples of the disclosure relate to an immersion sensor for electrochemical measurements and a method for manufacturing such an immersion sensor. Various examples of the disclosure relate to a measurement system for reading an immersion sensor and performing electrochemical measurements based on signals from the immersion sensor. BACKGROUND

[0002] Electrochemical measurements can be used in a variety of applications. For example, electrochemical reduction-oxidation measurements can be used to investigate biological or chemical assays.

[0003] To perform electrochemical reduction-oxidation measurements, an electrode and a counter electrode are immersed in a liquid. A potential difference or current is then measured between the electrode and the counter electrode. Sometimes one of the electrodes is biofunctionalized to measure specific properties of the assay.

[0004] Dip-in-well sensors are used, which also contain the electrodes. Typically, the sensors need to be replaced periodically, e.g., after each measurement, when the electrode surface reacts with the assay, e.g., by binding molecules to the biofunctionalized surface. Therefore, replaceable sensors are required. SUMMARY

[0005] There is a need for advanced immersion sensors and associated measurement systems for electrochemical measurements. In particular, there is a need for sensors that can be biofunctionalized, are easy to manufacture, and can be conveniently attached to the measurement system's mounting bracket.

[0006] This need is met by the features of the independent claims. The features of the dependent claims define embodiments.

[0007] An immersion sensor (hereinafter also simply sensor) for electrochemical measurements is disclosed. The sensor can be at least partially immersed in a fluid / assay. The sensor is designed to be immersed in an assay at its distal end.

[0008] Various types of electrochemical measurements can be facilitated, including but not limited to electrochemical reduction-oxidation measurements.

[0009] The sensor includes a base. The base may have an elongated shape.

[0010] The base has a first surface, a second surface and a perimeter.

[0011] Without loss of generality, the "first surface" will be referred to below as the "upper surface" and the "second surface" as the "lower surface." This is done for reasons of readability.

[0012] The sensor also includes at least one metal electrode. The metal electrode is located on top of the base. Alternatively, the metal electrode can be located on the bottom of the base. The metal electrode extends between the distal end and a proximal end of the sensor. The metal electrode is designed to be immersed in the assay to serve as an electrode or counter electrode for electrochemical measurements.

[0013] The sensor also includes a substrate plate, e.g., made of a semiconductor such as silicon. One possibility is for the substrate plate to be made of borosilicate. Other options include glass, ceramic, or polymers. The substrate plate can have an elongated shape. The substrate plate is attached with its second (lower) surface to the upper surface of the base. The attachment can be done with adhesive. The plate extends along the at least one metal electrode between the distal end and the proximal end.

[0014] Another metal electrode is arranged on the first (upper) surface of the substrate plate. This additional metal electrode also extends between the proximal and distal ends. This additional metal electrode can serve as an electrode or counter electrode for electrochemical measurements.

[0015] Accordingly, the immersion sensor can be a multi-part system. The first part is the base, which supports at least one metal electrode. Attached to this is the second part, namely the substrate plate, which supports the additional metal electrode.

[0016] Such a multi-part sensor design offers certain advantages. In particular, separate manufacturing steps can be performed for the at least one metal electrode attached to the base, on the one hand, and the additional metal electrode attached to the substrate plate, on the other. This allows sensitive manufacturing steps such as the biofunctionalization of a distal end of the at least one electrode or the additional electrode to be performed with little or no impact on other manufacturing steps of the other part.

[0017] More generally, the at least one metal electrode and the further metal electrode can be formed or manufactured separately on the base or the substrate plate, then after the formation of the electrodes, the substrate plate (may also be referred to as substrate plate) can be attached to the base.

[0018] According to examples, a sensing area of ​​the additional metal electrode located at the distal end of the sensor is biofunctionalized. Such biofunctionalization can, for example, involve attaching specific molecules to a metal surface of the additional metal electrode. These molecules can act as binding receptors to test chemical coupling with molecules in the assay.

[0019] The additional metal electrode also forms a connection area that extends away from the sensor area toward the proximal end of the sensor. The connection area may be narrower than the sensor area.

[0020] The width of the sensor area and the connection area of ​​the further metal electrode is defined in the plane of the respective metal layer perpendicular to the longitudinal direction of the sensor, which extends between the distal end and the proximal end.

[0021] In other words, the connection region can form a constriction of the additional metal electrode. The additional metal electrode has a narrow central section. This reduces the area of ​​the additional metal electrode facing the environment—and thus potentially in contact with the assay—in the connection region compared to a scenario in which the connection region has the same width as the sensor region. This makes the electrochemical measurement less sensitive to varying coverage ratios of the assay on the connection region. The signal of the electrochemical measurement therefore originates predominantly from the sensor region of the additional metal electrode. This provides a more reproducible signal, and the electrochemical measurement is more accurate.

[0022] The substrate plate can protrude from the top surface of the base and from the at least one metal electrode. Accordingly, the top surface of the substrate plate can be offset from the top surface of the base perpendicular to the plane of the additional electrode. In other words, the top surface of the overall sensor has a topography / profile. Such a topography of the sensor perpendicular to the plane of the at least one electrode on the base and the additional electrode arranged on the substrate plate can help secure the sensor in a holding clamp of a measuring system.

[0023] According to examples, the at least one metal electrode comprises a first metal electrode and the second metal electrode. The first metal electrode and the second metal electrode can be arranged symmetrically with respect to a central axis that runs parallel to or coincides with a central axis of the further metal electrode.

[0024] According to certain examples, the at least one metal electrode (located on top of the base) comprises a first metal electrode and a second metal electrode. The substrate plate can then be arranged between the first metal electrode and the second metal electrode. A symmetrical arrangement—mirror-symmetrical to the longitudinal central axis of the sensor—can be realized.

[0025] The base can have a narrow immersion area and a wide connection area. The narrow immersion area is used for immersion into the assay and is located at the distal end of the sensor, while the wide connection area serves to enable electrical contact between the at least one metal electrode and a measurement system, as well as between the further metal electrode and the measurement system.

[0026] The at least one metal electrode can comprise a connection region. The connection region is then arranged in the wide connection region of the base and has a width (perpendicular to the longitudinal direction of the at least one metal electrode) that is not less than twice the width of the at least one metal electrode at its distal end. The connection region can be designed as a tab or wing that extends away from the rod-shaped sensor region of the at least one metal electrode. This can form support surfaces for electrical pins of a holder of the measuring system. This allows for reliable and robust electrical contact to be established.

[0027] The base may include one or more engagement features for aligning the immersion sensor and the measurement system retaining bracket.

[0028] The one or more engagement features may be formed as protrusions, ribs, or notches in a periphery of the base. The one or more engagement features may assist in the attachment process of the sensor to the retaining clip. Reliable relative alignment can be ensured. This prevents relative movement of the sensor and the retaining clip during measurement. This reduces noise in the signals acquired by the sensor. This leads to higher accuracy of the electrochemical measurement.

[0029] For example, one or more magnets can be provided to attach the sensor to the measuring system's mounting bracket using magnetic force. This can enable reliable and simple installation.

[0030] In principle, it would be possible for the at least one metal electrode arranged on the top or bottom of the base and the further metal electrode arranged on the top of the substrate plate to consist of different metals. Different manufacturing processes can be used to deposit such a metal. For example, the at least one metal electrode arranged on the top of the elongated base can consist of screen-printed silver. The further metal electrode can consist of a thin gold film. Such a thin gold film can be deposited, e.g., by vapor deposition or sputtering. The elongated base can be made of acrylic.

[0031] A method for manufacturing an immersion sensor for electrochemical measurements comprises manufacturing a base. The method also comprises forming at least one metal electrode on the base. The method also comprises manufacturing a substrate plate. The method also comprises forming another electrode on the substrate plate. The method further comprises attaching the substrate plate to the base after forming the at least one metal electrode and after forming the another electrode.

[0032] In some examples, the at least one metal electrode is made of screen-printed silver. Accordingly, it would be possible to form the at least one metal electrode by screen-printing silver.

[0033] In some examples, the further metal electrode may consist of, or at least contain, gold or another precious metal. The further electrode may contain platinum or aluminum. Forming the further electrode may involve depositing a thin film of such a material. This may be done, for example, by vapor deposition, sputtering, or thermal deposition.

[0034] By separately manufacturing the at least one electrode on the base and the further electrode on the substrate plate, deterioration of the further electrode or biofunctionalization thereof during the process of forming the at least one metal electrode is avoided. Furthermore, biofunctionalization is more flexible because the at least one further electrode or the base is separated from the substrate plate at this stage.

[0035] A measurement system for performing electrochemical measurements of assays in wells of a multi-well plate is disclosed. The measurement system comprises a base, e.g., a base plate, a housing, or a frame.

[0036] A robotic actuator comprising a movable platform is mounted on the base. The movable platform can be relatively movable with respect to a multi-well plate held by a sample holder arranged on the base of the measurement system. For example, the robotic actuator can have two degrees of freedom to position the movable platform in a plane parallel to the multi-well plate.

[0037] The measurement system also includes a holding clamp. The holding clamp is attached to the movable platform. This means that the holding clamp moves along with the movable platform. The holding clamp serves to releasably secure an immersion sensor. The immersion sensor comprises multiple electrodes. Aspects relating to such an immersion sensor have been disclosed above. The immersion sensor can be immersed into the multiwell plate by a corresponding immersion mechanism (e.g., a linear motor) attached to the movable platform. It would also be conceivable for the movable platform to be three-dimensionally repositionable, i.e., to flexibly position the movable platform relative to different wells of the multiwell plate and to immerse the sensor into a corresponding well.

[0038] The multiple electrodes are used to capture signals that form the basis for the electrochemical measurement. For example, a current flow or a potential difference between the multiple electrodes can be detected.

[0039] The measuring system also includes an analog-to-digital converter. The analog-to-digital converter is also located toward the moving platform. This means that the analog-to-digital converter moves along with the moving platform. The analog-to-digital converter is configured to establish an electrical connection to the multiple electrodes of the immersion sensor when the immersion sensor is grasped by the retaining clip, and to convert analog electrical signals received from the immersion sensor into digital signals.

[0040] A control circuit of the measuring system is arranged on the basis of the measuring system and is configured to perform the electrochemical measurements based on the digital signals.

[0041] By placing the analog-to-digital converter on the movable platform, the signal path between the sensor and the analog-to-digital converter is reduced compared to a scenario where the analog-to-digital converters are located on the base. This can increase the signal-to-noise ratio, thus improving the quality of the electrochemical measurements.

[0042] The retaining clip can be configured to releasably hold the sensor in place using a spring-loaded clamping mechanism. For example, a lid can be opened by the user (applying a force against the spring bias) to insert the sensor into the retaining clip, and then the lid can be closed using the spring bias to hold and secure the sensor in the retaining clip.

[0043] This technology allows for easy sensor replacement. Furthermore, the sensors are secured with minimal relative movement between the sensor and the mounting bracket, reducing the electrical noise picked up by this movement.

[0044] To connect the multiple electrodes, the retaining clip contains several contact pins corresponding to various examples. These contact pins can also be spring-loaded to ensure reliable electrical contact between each pin and the electrodes.

[0045] According to examples, the retaining clip may have a corresponding pair of contact pins for each of the plurality of electrodes. The control circuit may then measure a current flow between the contact pins of each pair to determine whether the immersion sensor has been properly secured by the retaining clip. In other words, a test mode may be activated to check whether the electrical contact between the sensor and the analog-to-digital converter is properly established. For example, current fluctuations may be monitored, and if the current fluctuations exceed a certain threshold, it may be determined that the retaining clip is only loosely engaging the sensor. Alternatively or additionally, the signal level of a current flowing between the contact pins of each pair may be determined, and the current amplitude may be used to assess whether the retaining clip is properly engaging the sensor.

[0046] After test mode has ended—i.e., after determining that the immersion sensor has been properly gripped by the retaining clip—measurement mode can begin. In measurement mode, the control circuit is configured to perform the electrochemical measurement based on current flow, e.g., through a single contact pin of each contact pin pair. This allows, for example, the current flow between the contact pins of two different pairs to be monitored. This reduces the number of channels required by the ADC.

[0047] The retaining clip may include structural guide features to align the immersion sensor with a plurality of contact pins of the retaining clip. Such guide features may include a notch that engages the corresponding protrusion of the sensor. Likewise, a protrusion of the retaining clip could engage the corresponding notch of the sensor. The notch may extend in a direction perpendicular to an offset between the plurality of contact pins. This ensures that the contact pins are correctly positioned on the respective contact areas of the electrodes.

[0048] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified but also in other combinations or in isolation without this going beyond the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a top perspective view of an immersion sensor 100 for electrochemical measurements according to various embodiments. Fig. 2 shows schematically the connection of the sensor of Fig. 1 to a measuring system according to various examples. Fig. 3 is a flowchart of a method for manufacturing an immersion sensor for electrochemical measurements according to various examples. Fig. Figure 4 schematically illustrates details of the measuring system. Fig. 5 schematically shows a retaining clip for releasably fastening an immersion sensor according to various examples. Fig. 6 is a top perspective view of an immersion sensor 100 for electrochemical measurements according to various examples. Fig. 7 is a perspective view from below of the immersion sensor 100 of Fig. 6. Fig. 8 is a top perspective view of a plurality of sensors arranged in a common retaining bracket according to various examples. Fig. 9 is a perspective view from below of the system of Fig. 8. Fig. 10 is a schematic plan view of multiple sensors with a common base according to various examples. Fig. 11 is a schematic bottom view of the system of Fig. 10. DETAILED DESCRIPTION

[0049] Embodiments of the invention will be described in detail below with reference to the accompanying drawings. It should be understood that the following description of the embodiments is not to be construed in a limiting sense. The scope of the invention is not intended to be limited by the embodiments described below or by the drawings, which are for illustrative purposes only.

[0050] Fig. 1 is a perspective view of an immersion sensor 100 according to various examples. The sensor 100 has a generally elongated shape, i.e., it extends along a longitudinal direction 51. A corresponding longitudinal central axis 55 (located at the center of the sensor 100 along a width direction 52) of the sensor 100 is shown (dashed-dotted line) extending between a distal end 191 and a proximal end 192.

[0051] The sensor 100 includes an elongated base 101 extending between the distal end 191 and the proximal end 192.

[0052] The base 101 has an upper surface 102 and a lower surface (in Fig. 1 not visible). The upper surface 102 is flat and extends in a plane defined by the longitudinal direction 51 and a width direction 52.

[0053] The base 101 includes a narrow sensor area 105 (for immersion in a well) at the distal end 191 and a wider connection area 106 to enable electrical contact between a measuring system and a plurality of electrodes 150, 155, 130 of the sensor 100.

[0054] The metal electrodes 150, 155 are arranged on the upper surface 102 of the base 101 and extend between the distal end 191 and the proximal end 192. The metal electrode 150, 155 can be made, for example, of silver (in particular silver paste) by a screen printing process.

[0055] The metal electrode 130 is arranged on the upper side 122 of an elongated substrate plate 121, which is connected with its underside (in Fig. 1 not visible) is attached to the top side 102 of the base 101. The elongated substrate plate 121 extends along the metal electrodes 150, 155 between the distal end 191 and the proximal end 192.

[0056] The electrode 130, e.g., a thin metal film possibly containing gold, is arranged on the top side 122 of the elongated substrate plate 121. Such a thin film can be defined by lithography, e.g., by defining a lithography mask and subsequently depositing the thin film, or by first forming the thin film and subsequently etching it using a lithography mask.

[0057] By attaching the substrate plate 121 to the top surface 102 of the base 101, the elongated substrate plate 121 protrudes from both the top surface 102 of the elongated base 101 and the metal electrodes 150, 155. The corresponding offset 139 is shown in Fig. 1 marked.

[0058] This offset 139 - which extends in a thickness direction 53, perpendicular to the longitudinal direction 51 and the width direction 52 - facilitates the alignment of the sensor 100 in a holding clamp of the measuring system by providing a guide for the relative positioning along the width direction 52.

[0059] As in Fig. 1, the arrangement of the electrodes 150, 155, 130 is mirror-symmetrical about the central axis 55. The electrode 130 is arranged between the electrodes 150, 155 along the width direction 52.

[0060] In particular, a distance between a sensor region 151 of the electrode 150 and a sensor region 131 of the electrode 130 is equal to a distance between the sensor region 131 of the electrode 130 and a sensor region 156 of the electrode 155. Accordingly, it is also possible to perform the electrochemical measurement by determining a current or a voltage between the electrode pair 130, 150 or between the electrode pair 155, 130.

[0061] The sensor area 131 of the electrode 130 can be biofunctionalized (not shown).

[0062] Adjacent to the sensor region 131 is a connection region 132, which tapers in the width direction 52 compared to the sensor region 131, as well as with respect to a connection region 134 for engaging with one or more electrical pins of a holding clip of a measurement system and thereby establishing electrical contact. By having the connection region 132 less wide than the sensor region 131, variable fill levels of the assay, which lead to different coverage levels of the connection region 132, have a smaller impact on the measurement signal compared to the scenario in which the connection region 132 would have the same width as the biofunctionalized sensor region 131. The narrower width of the connection region 132 makes the electrochemical measurement more accurate overall.

[0063] Also in Fig. 1 shows the connection region 152 (may also be referred to as the "contact region") of the electrode 150, which has a greater width (along the width direction 52) than the sensor region 151 to be immersed in the assay. Likewise, the width of the connection region 157 of the electrode 155 is greater than the width of the sensor region 156 of the electrode 155. The width of the connection regions 152, 157 of the electrodes 150, 155 generally cannot be less than three times the width of the electrodes 150, 155 at the distal end 191. This facilitates both reliable electrical contact with pins of the measurement system at the connection regions 152, 157 and the ability to immerse the sensor 100 in a narrow well.

[0064] The shape of the elongated base 101 with the wide connection region 106 and the narrow sensor region 105 facilitates the alignment and fastening of the sensor 100 in a holding clamp of a measuring system. In particular, the base area of ​​the connection region 106 of the base 101 can be aligned in a corresponding recess of the holding clamp, which is facilitated by the edges of the connection region 106. In general, the elongated base 101 can have one or more engagement features for aligning the sensor 100 in the holding clamp, e.g., ribs, edges, etc. formed in a circumference of the base 101. It would also be possible for the sensor 100 to comprise one or more magnets to magnetically attach the sensor 100 to the holding clamp. The magnets can, for example, be arranged in the connection region 106 (in Fig. 1 not shown) to the base 101.

[0065] Fig. Figure 2 schematically shows how the sensor 100 is aligned and attached to a support bracket 42 of a measurement system 40, such that an electrical connection is established between the terminal areas of each of the electrodes 150, 155, 130 and a control circuit 41 of the measurement system 40. The sensor 100 is shown immersed in an assay 90 at its distal end 91.

[0066] Fig. Figure 3 is a flow diagram illustrating a method for manufacturing an immersion sensor for electrochemical measurements in a well. The sensor 100 according to Fig. 1 can, for example, be calculated according to the procedure of Fig. 3 can be produced. Fig. 3 illustrates a method for manufacturing a multi-part sensor with separate processing strands 1001 and 1011.

[0067] In processing line 1001, an elongated base, e.g. made of acrylic, is produced in box 1005. Then, in box 1010, one or more electrodes are formed on this base. Relatively high temperatures can be used, e.g., around 150°C to 200°C. For example, multiple electrodes can be produced using a screen printing process. Silver electrodes can be formed. Silver screen printing is a technique used to apply metallic silver ink to a variety of surfaces such as paper, fabric, or plastic. A stencil with the desired design is created on a fine-mesh screen, leaving the areas to be printed open. The screen is then placed on the surface to be printed, and the silver ink is pressed through the open areas with a squeegee. The ink is transferred to the surface, creating the desired silver metallic design.Finally, the printed material is dried or cured to ensure proper ink adhesion. Typical curing temperatures are between 150 and 175°C.

[0068] Such temperatures can damage biofunctionalized surfaces. Accordingly, the second production line 1001 is separated from the first production line 1001.

[0069] In box 1015, a substrate plate is manufactured. A chip can be produced, for example, by dicing a wafer. Typical dimensions of the substrate plate are: thickness: 250 µm–500 µm; length along a longitudinal direction of the elongated substrate plate: 1 cm–5 cm; width perpendicular to the thickness and longitudinal direction: 1 mm–1 cm.

[0070] In box 1020, electrodes are then formed on the elongated substrate plate using a lithography mask. For example, the lithography mask can first be formed on the elongated substrate plate, and then the metal for the electrodes can be applied. This can be done, for example, by chemical or physical vapor deposition. The mask can then be removed again. Alternatively, a continuous gold film can first be deposited, followed by the mask being formed on the gold film (a reverse mask compared to the first scenario), and excess gold can then be removed by etching, for example, by wet etching or dry etching.

[0071] In Box 1025, at least part of the electrode(s) formed in Box 1020 can be biofunctionalized. Various methods are available for the biofunctionalization of the electrodes, e.g., the formation of self-assembling monolayers. In this case, the sulfur in an alkanethiol adheres to the electrode surface, while the other end of the molecule can be functionalized with various chemical groups. In another variant, biomolecules can be adsorbed directly onto the surface, exploiting the affinity between metal and certain functional chemical groups. Another option involves a layered assembly in which oppositely charged polyelectrolytes, proteins, or nanoparticles form a multilayer structure. In a further scenario, biomolecules can be covalently bound to the surface of electrodes through bioconjugation.This can involve using a reactive group of the biomolecule or a linker molecule that connects the electrode surface and the biomolecules. Another possibility is electrochemical grafting, in which specific organic molecules can be grafted onto the surface of the electrodes using an electrochemical process. In each of these scenarios, the biofunctionalized surface of the electrode can be sensitive to the temperatures required for the formation of the electrodes in box 1010; therefore, it is beneficial to separate processing strands 1001 and 1011.

[0072] Finally, in box 1030, the substrate plate carrying the electrode(s) formed in box 1020 is attached to the base carrying the electrode(s) formed in box 1010. For example, an adhesive bond may be established.

[0073] In Fig. 4, details of the measurement system 40 are shown schematically. The measurement system 40 includes the control circuit 41. The control circuit 41 may be implemented by a general-purpose central processing unit (CPU), a field-programmable gate array (FPGA), and / or an application-specific integrated circuit (ASIC). The control circuit 41 may include a memory that stores program code executed by the CPU, the FPGA, or the ASIC. The control circuit 41 is configured to perform an electrochemical measurement based on digital signals originating from an analog-to-digital converter (ADC) 822. The digital signal obtained from the ADC 822 is an indicator of a current flow or a potential difference between the electrodes of an immersion sensor, such as the one described above in connection with Fig. Sensor 100 described in section 1.

[0074] The control circuit 41 is arranged on a fixed base 810 of the measuring system 40. The ADC 822 is arranged on a movable platform 812 of a robot actuator 811. The movable platform 812 can be moved relative to the fixed base 810 by means of the robot actuator 811. The robot actuator 811 is configured to reposition the movable platform 812 within a specific measuring range 813. Such repositioning can, for example, have two degrees of freedom, as shown in Fig. 4, as indicated by the arrows. For example, two motors can be provided, coupled to the movable platform 812 via a belt system. It would also be possible to use a robot arm with more than two degrees of freedom.

[0075] The ADC 822 converts analog signals originating from the sensor, which engages the retaining clip 42, also arranged on the movable platform 812.

[0076] By providing the ADC 822 to the movable platform 812, the cable length between the sensor engaged with the retaining clip 42 and the ADC 822 can be kept comparatively short. Accordingly, the signal-to-noise ratio of the analog signal converted by the ADC 822 is comparatively high. This increases the accuracy of the electrochemical measurements performed by the control circuit 41. It has been shown that such placement of the ADC 822 in close proximity to the sensors is helpful for performing the electrochemical measurements with high accuracy, since the measured currents are often on the order of nanoamperes.

[0077] Fig. 5 schematically illustrates a possible implementation of the retaining clip 42. In the example of Fig. 5, the retaining clip 42 is shaped to releasably engage the sensor 100.

[0078] For this purpose, a first notch or recess 854 is provided, which is shaped to engage the connection area 106 of the base 101 of the sensor 100; furthermore, a second notch or recess 855 is provided, which has a shape adapted to the protruding substrate plate 121. More generally, the retaining clip may have a plurality of engagement features or guide features to align the sensor electrodes with a plurality of contact pins 861, 862, 863 of the retaining clip 42.

[0079] In the scenario of Fig. 5, the retaining clip 42 includes a cover 851 configured to releasably engage the sensor. The cover 851 may be spring-loaded. Other types of clamping mechanisms are also generally conceivable.

[0080] It is also possible that the multiple contact pins 861-863 are spring-loaded. This means that the contact pins 861-863 can be pressed against the surfaces of the electrodes by a corresponding spring force.

[0081] As in Fig. As shown in Figure 5, the retaining clip 42 comprises three pairs of electrical contact pins 861-863. One pair of electrical contact pins 861-863 is provided for each electrode 130, 150, 155. This means that the connection regions 134, 152, 157 of each of the electrodes 130, 150, 155 are contacted by two contact pins 861-863 each. For example, the connection region 152 can be contacted by both contact pins 861, the connection region 134 by both electrical contact pins 863, and the connection region 157 by both contact pins 862 (see Fig. 1). The control circuit 41 of the measuring system 40 can then, in a test mode, measure a current flow between the contact pins of each pair, e.g., between contact pins 861 of the respective pair, to determine whether the sensor has been properly engaged by the retaining clip 42. For example, only when there is a sufficiently large current flow between the contact pins of each of the three pairs can it be determined that the sensor is properly engaged, and then the electrochemical measurement can be performed. Alternatively or additionally, a temporal change in the current can also be monitored. The electrochemical measurement can then be based on a current flow through an individual contact pin of each pair. For example, the electrochemical measurement can be based on a current flow from one of the electrical contact pins 863 to one of the electrical contact pins 861.By using only a single contact pin per electrode for the actual electrochemical measurement, the number of channels required for the ADC is reduced.

[0082] Scenarios were discussed above in which the metal electrodes 150, 155 are arranged on the upper surface 102 of the elongated base 101. This is only one example, and another example is shown in Fig. 6 and Fig. 7 shown. Fig. 6 is a top perspective view of another embodiment of the sensor 100. As with the embodiment in Fig. 1, the elongated substrate plate 121 is attached to the top surface 102 of the elongated base 101. In this scenario, the metal electrodes 150, 155 are arranged on the bottom surface 103 of the elongated base 101, as shown in the bottom perspective view of Fig. 7. As can be seen from Fig. 6 and Fig. As can be seen in Figure 7, the metal electrodes 150, 155 are arranged symmetrically with respect to a central axis 998, which is parallel to the central axis 999 of the electrode 130. Both the central axis 998 and the central axis 999 and the central axis 55 of the sensor (see Figure 7) are parallel. Fig. 1) are aligned with each other and in one plane.

[0083] Fig. Figure 8 is a perspective top view of a system 980 with multiple sensors 100. The multiple sensors 100—here four sensors, but a larger or smaller number would generally be possible—are arranged in a row. In the illustration of Fig. 8, the sensors 100 are each according to the variant of Fig. 6 and Fig. 7; in principle, however, the sensors could also be set up differently, for example, according to the variant of Fig. 1 (ie all electrodes 130, 150, 155 are arranged on the same side of the sensor 100).

[0084] The system 980 also includes a fastening structure 49 which is secured with a clamp (see Fig. 5: bracket 42) for fastening the system. The bases 101 of the sensors 100 are attached to the fastening structure 49, e.g., by gluing. The fastening structure 49 has a through-hole that enables contacting of the connection area 134. This is shown in Fig. 9, the lower perspective view, which corresponds to the upper perspective view of Fig. 8 corresponds.

[0085] If several sensors 100 are mounted next to each other, as in Fig. 8 and Fig. 9, it is possible that a single base 101 is used for the multiple sensors 100. This is shown in the schematic plan view of Fig. 10 and in the schematic bottom view of Fig. 11. Such a scenario can also be applied to configurations in which the metal electrodes 150, 155 are attached to the top 102 of the base, e.g., as in connection with Fig. 1. Such a device facilitates the use of a common retaining clip (in Fig. 10 and Fig. 11 not shown), which engages the individual base 101 at the respective engagement features 989 at the outer ends (through holes). Such an implementation of the system 980 using a single, integrated base 101 has the following advantages: easier manual handling, since each small sensor 100 does not have to be handled individually. In the embodiments of the Fig. 8-11, it is possible to provide larger engagement features 989 at both ends of the array of sensors 100, allowing for easy attachment.

[0086] Although the invention has been shown and described with reference to certain preferred embodiments, equivalents and modifications will become apparent to those skilled in the art after reading and understanding the specification. The present invention includes all such equivalents and modifications and is limited only by the scope of the appended claims.

[0087] For illustrative purposes, the surfaces of the substrate plate and the surfaces of the base have been referred to as the "top" and "bottom." This is not intended to be a limiting or absolute term: the top and bottom surfaces are located on opposite sides of the respective element.

Claims

[1] An immersion sensor (101) for electrochemical measurements by immersing it at a distal end (191) into an assay (90), the immersion sensor (101) comprising: - a base (101), - at least one metal electrode (150, 155) arranged on a first surface (102) or a second surface (103) of the base (101) and extending between the distal end (191) and a proximal end (192) of the immersion sensor (100), - a substrate plate (121) attached at its second surface to the first surface (102) of the base (101) and extending along the at least one metal electrode (150, 155) between the distal end (191) and the proximal end (192), and - a further metal electrode (130) arranged on a first surface of the substrate plate (121) and extending between the distal end (191) and the proximal end (192). [2] Immersion sensor (100) according to claim 1, wherein a sensor area (131) of the further metal electrode (130) arranged at the distal end (191) is biofunctionalized, wherein a connection region (132) of the further metal electrode (130), which extends from the sensor region (131) to the proximal end (192), has a smaller width than the sensor region. [3] The immersion sensor (300) according to claim 1 or 2, wherein the substrate plate (121) protrudes from the first surface (102) of the base (101). [4] Immersion sensor (100) according to one of the preceding claims, wherein the at least one metal electrode (150, 155) comprises a first metal electrode (150) and a second metal electrode (155). [5] Immersion sensor (100) according to claim 4, wherein the first metal electrode (150) and the second metal electrode (155) are arranged symmetrically with respect to a central axis (998) which is parallel to a central axis (999) of the further metal electrode (130). [6] Immersion sensor (100) according to one of the preceding claims, wherein the base (101) comprises a narrow immersion region (105) and a wide connection region (106) to enable electrical contact between the at least one metal electrode (150, 155) and a measuring system and between the further metal electrode (130) and the measuring system (40). [7] The immersion sensor according to claim 6, wherein the at least one metal electrode (150, 155) comprises a terminal region (152, 157) arranged in the wide terminal region (106) of the base (101), which has a width perpendicular to a longitudinal direction (51) of the at least one metal electrode (150, 155) that is not less than three times a width of the at least one metal electrode (150, 155) at the distal end (191). [8] Immersion sensor (100) according to one of the preceding claims, wherein the base (101) has one or more engagement features for aligning the immersion sensor (100) in a retaining clip (42) of a measuring system (40). [9] Immersion sensor (100) according to one of the preceding claims, further comprising - one or more magnets for attaching the immersion sensor (100) to a holding clamp (42) of a measuring system (40). [10] System (980) comprising a plurality of immersion sensors (100) according to any one of the preceding claims. [11] The system of claim 10, wherein the bases (101) of the plurality of immersion sensors (100) are integrally formed. [12] The system of claim 10 or 11, wherein the plurality of immersion sensors (100) are arranged in a row, the system further comprising: - a plurality of engagement features (989) arranged at both ends of the row for aligning the immersion sensor (100) in a retaining bracket (42) of a measuring system (40). [13] A method of manufacturing an immersion sensor for electrochemical measurements, the method comprising: - Providing a base (101), - forming at least one metal electrode (150, 155) on the base, - producing a substrate plate (121), - forming a further electrode (130) on the substrate plate, - after forming the at least one metal electrode and the further electrode, attaching the substrate plate to the base. [14] The method of claim 13, further comprising: - biofunctionalization of at least a part of the further electrode, wherein the substrate plate is attached to the base after the biofunctionalization of at least a part of the further electrode. [15] The method according to claim 13 or 14, wherein the manufactured immersion sensor is the immersion sensor according to any one of claims 1 to 12.

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