Fluid sensor device with a gel portion covering at least partially one electrode and method of using such a fluid sensor device

Abstract

In various aspects, a fluid sensor device and a method of using such a fluid sensor device are provided. According to some illustrative embodiments herein, the fluid sensor device comprises a sensor substrate, at least one sensor electrode formed on the sensor substrate, and at least one gel portion associated with the at least one sensor electrode. The at least one sensor electrode has a sensor surface for exposure to a sample liquid in an operational state of the fluid sensor device and the sensor surface of the at least one electrode is at least partially covered by the associated gel portion in an non-operational state of the fluid sensor device.

Description

[0001] FLUID SENSOR DEVICE WITH A GEL PORTION COVERING AT LEAST PARTIALLY ONE ELECTRODE AND METHOD OF USING SUCH A FLUID SENSOR DEVICE

[0002] Field of the invention

[0003] The present invention relates to a fluid sensor device, preferably a liquid sensor device such as a water sensor device, and to a method of using such a fluid sensor device.

[0004] Background

[0005] Sensors of this type are applied in a great variety of applications where measurements are carried out for measuring physical and chemical characteristics of a fluid. For example, such sensors may be intended for carrying out measurements in chemistry, in the food industry for water quality control, such as the quality of potable water or water in swimming pools and the like.

[0006] In the context of the determination of the quality of drinking water, it is important to monitor the water quality for reasons of human health, limited resources and industrialization of countries by means of permanent monitoring and / or mobile monitoring via hand held devices. This is an important application of fluid sensors as water is capable of dissolving different particles, which can reduce its quality. Herein, the water quality may be determined on the basis of chemical, physical and electrical parameters so as to identify dispersed particle in water consisting of chemical and physical materials including heavy metals, minerals, toxic organic and inorganic materials and its pH value. Therefore, electrical conductivity, temperature, and the pH value of a fluid are major parameters for analyzing the quality of a fluid.

[0007] In general, measurements of a fluid characteristic, such as the characteristic of a liquid, preferably an aqueous liquid, are for example measurements of pH, chlorine concentration, oxidation reduction potential, and solute concentrations which are of interest in a wide variety of industrial, commercial, and domestic processes and situations.

[0008] In a swimming pool, the quality of the water is closely related to the pH and the oxidation reduction potential of the water. In swimming pools, the oxidation reduction potential of the water is a measure of the free chlorine level in the water, and the solute level may be of chlorine species resulting from addition of, for example, hypochlorous acid or sodium hypochlorite or sodium dichloroisocyanurate (NaDCC). The concentrations of free chlorine and other chlorine species relate to the biological antiseptic quality of the water. The pH value and concentration of chlorine species (“chlorine level”) of swimming pool water are usually monitored by hand and the owner or caretaker in charge of maintaining the swimming pool is repeatedly taking samples from the swimming pool water to determine the amount of chemicals needed to adjust to the proper pH and / or chlorine level in the swimming pool.

[0009] Fluid sensors for such measurements are often operated on a potentiometric electrochemical principle that incorporates a reference electrode and a sensing electrode representing sensor electrodes of a fluid sensor device. Conventional reference electrodes for use in such potentiometric electrochemical measurements typically incorporate an internal reference fill solution in contact with an electrode in contact with a test solution through a porous junction which allows a slow leak of the internal reference fill solution to provide the necessary electrolytic contact with the liquid being tested. A metal or electrochemical electrode in contact with a test solution completes the circuit and an electrical potential on the reference electrode remains relatively constant while the sensing electrode responds to chemical changes in the test solution.

[0010] Usually, fluid sensors to be used in measurements as described above have a considerable settle time limiting the measurement speed together with calibration steps, which counteract repeated measurement and require some preparation of the fluid sensor device prior to its application as a measurement device. If the fluid sensors are not properly prepared and stored, the settle time and measurement speed deteriorates throughout the use of a fluid sensors lifetime and its long-term stability decreases.

[0011] In view of the above situation it is desirable to provide a fluid sensor device with improved accuracy, quality and speed of measurement that has a reduced settle time and improved long term stability behavior. Furthermore, it is desirable to provide a method of using such a fluid sensor device in order to achieve a reduced settle time and improved long term stability behavior for the fluid sensor.

[0012] Summary

[0013] In a first aspect of the present disclosure, a fluid sensor device is provided. In some illustrative embodiments herein, the fluid sensor device may be a liquid sensor device e.g. a liquid sensor device for aqueous liquids, in particular a water sensor device.

[0014] In the illustrative embodiments of the first aspect, the fluid sensor device comprises a sensor substrate, at least one sensor electrode formed on the sensor substrate, the at least one sensor electrode having a sensor surface for exposure to a sample liquid in an operational state of the fluid sensor device, and at least one gel portion associated with the at least one sensor electrode. The sensor surface of the at least one sensor electrode is at least partially covered by the associated gel portion in a non-operational state of the fluid sensor device. Preferably, the sensor surface of the at least one electrode is completely covered by the associated gel portion in the non-operational state of the fluid sensor device.

[0015] In some illustrative examples herein, the fluid sensor device may have a single sensor electrode formed on the sensor substrate, optionally coupled with a separate reference electrode provided as a remote second sensor electrode not present on the sensor substrate, wherein the sensor surface of the single sensor electrode on the sensor substrate is at least partially, preferably completely, covered by the gel portion which is provided as a single gel portion in the fluid sensor device.

[0016] In some other illustrative examples herein, the fluid sensor device may have two or more sensor electrodes formed on the sensor substrate and fluid sensor device may further comprise a single gel portion associated with the at least two sensor electrodes. That is, the sensor surfaces of the at least two sensor electrode are at least partially, preferably completely, covered by the single gel portion in the non-operational state of the fluid sensor device. For example, at least one sensor surface of the at least one sensor surface may be partially covered by the single gel portion and / or at least one sensor surface of the at least one sensor surface may be completely covered by the single gel portion. This formulation means that there is one sensor surface and this sensor surface is at least partially covered by the single gel portion or there are at least two sensor surfaces and one of the following three possibilities (a), (b), (c) may be implemented: (a) all of the at least two sensor surfaces are partially covered by the single gel portion; (b) all of the at least two sensor surfaces are completely covered by the single gel portion; and (c) there are two subsets of sensor surfaces (first and second subsets of sensor surfaces, each subset comprising one or more sensor surfaces such that a partition of the set of sensor surfaces provided by the at least two sensor surfaces is provided, the partition of this set indicating a grouping of the at least two sensor surfaces into non-empty subsets given by first and second subsets) out of the at least two sensor surfaces, the first subset of sensor surfaces being partially covered by the single gel portion and the second subset of sensor surfaces being completely covered by the single gel portion.

[0017] In some other illustrative examples herein, the fluid sensor device may comprise a plurality of sensor electrodes and a plurality of gel portions, wherein each gel portion is associated with a subset of sensor electrodes of the plurality of sensor electrodes. Each subset may be composed of at least one sensor electrode. That is, a single gel portion may be associated with a single electrode of the plurality of electrodes or each gel portion may be associated with one or more out of the plurality of sensor electrodes. As the gel portion at least partially covers the associated sensor electrode(s), it is possible to ensure that the sensor electrode(s) of the fluid sensor device on the sensor substrate may be stored under appropriate conditions such that the quality, the speed of measurement and the long term stability of the fluid sensor device is maintained. In particular, the sensor electrode(s) of the fluid sensor device on the sensor substrate can be stored in an appropriate humidified or wet environment with a predetermined chemical characteristic considered optimum for storing the electrode of the fluid sensor device in a non-operational state of the fluid sensor device. Therefore, the time for preparation and the settlement time of the fluid sensor device may be considerably shortened due to the at least one gel portion ensuring that the sensor electrode(s) is / are stored under optimum conditions.

[0018] Herein, the expression “gel” is to be understood as a semi solid with properties ranging from soft and weak to hard and tough, in particular representing a substantially dilute cross linked system which exhibits no flow when in the steady state, although the liquid phase in a gel may still diffuse through the system. Under phenomenological considerations, a gel may be understood as representing a soft, solid or solid like material consisting of two or more components, one of which is a liquid, present in substantial quantity. In other words, a gel may be understood as representing a sol in which solid particles are mashed such that a rigid or semi-rigid mixture results, where cross-linking within the gels polymer or colloidal network causes a gel to behave as a solid in its steady state and makes it feel tacky. Herein, “sol” denotes a type of colloid in which solid particles are suspended in a liquid. The particles in a sol are very small and a colloidal solution shows the Tyndall effect and is stable.

[0019] In accordance with some illustrative embodiments of the first aspect, the fluid sensor device may be provided as a sensor card having a card body with a recess into which the sensor substrate is accommodated. For example, the sensor card may be a smart card or the sensor card may be of a smart card type comprised of a card body. The card body may be a laminated card body as used in the fabrication of smart cards, for example, representing a laminated sheet body comprising one or more optional overlay foils, one or more plastic sheets made of PVC (polyvinyl chloride), ABS (acrylonitrile butadiene styrene), PP (polypropylene), Teslin or other materials, and one or more optional inlays containing electronic components such as battery, LED, LCD display, buttons, fingerprint sensors, buzzers, and the like. The recess may be formed in the card body such that the sensor substrate is accommodated into the recess such that the surface of the card body having the recess formed therein is flush after accommodation of the sensor substrate. In other examples, the sensor substrate with the at least one sensor electrode formed thereon may be accommodated into the recess such that the sensor with the sensor electrode(s) formed thereon is flush in the surface of the card body. Accordingly, a compact and bendable fluid sensor device may be provided, allowing mobile measurements.

[0020] In other illustrative embodiments of the first aspect, the fluid sensor device may further comprise a sensor covering element equipped with the at least one gel portion. The sensor covering element may comprise a fixation structure of the at least one gel portion in the covering element comprising at least one of a hydrogel clip, a plastic frame with clamping and a plastic frame with textile mesh. Herein the at least one gel portion is reliably mounted to the sensor covering element so as to be in contact with the at least one sensor electrode in the non-operational state in which the sensor covering is arrange with respect to the sensor substrate so as to cover the at least one electrode. Accordingly, the at least one sensor electrode may be exposed to the at least one gel portion in the non-operational state.

[0021] In some illustrative examples herein, one sensor electrode may be formed on the sensor substrate and the sensor covering element may have a gel portion arranged thereon. In the non-operational state, the gel portion may be in contact with the sensor electrode when the sensor covering element is arranged with respect to the sensor substrate such that the sensor electrode is covered by the sensor covering element. For example, the sensor covering element may have a projecting nose or pin formed on a surface region of the sensor covering element facing towards the sensor electrode in the non-operational state such that the projecting nose or pin faces towards the sensor electrode in the non-operational state. The projecting nose or pin may be configured for mechanical engagement with the gel portion such that the gel portion may be removably fixed to the sensor covering element. For example, the gel portion may have an engagement opening formed therein such that the projecting nose or pin may releasably engage with the engagement opening. Accordingly, upon the projecting nose or pin being positioned in alignment with the sensor electrode, the gel portion is in contact with the sensor electrode in the non-operational state. In some other examples herein, more than one projecting nose or pin and engagement opening may be formed for removably coupling the gel portion with the sensor covering element. In some alternative examples herein, the projecting nose(s) or pin(s) may be formed on the gel portion, while the sensor covering element may have respective engagement opening(s) formed therein.

[0022] In some other illustrative examples herein, two or more sensor electrodes may be formed on the sensor substrate and the sensor covering element may have two or more gel portions arranged thereon. In the non-operational state, the gel portions may be in contact with the sensor electrodes (one gel portion in contact with a dedicated one of the sensor electrodes) when the sensor covering element is arranged with respect to the sensor substrate such that the sensor electrode is covered by the sensor covering element. For example, the sensor covering element may have at least one projecting nose or pin formed on a surface region of the sensor covering element facing towards the sensor electrodes in the non-operational state such that the at least one projecting nose or pin faces towards the sensor electrodes in the non-operational state. The at least one projecting nose or pin may be configured for mechanical engagement with the gel portions such that the gel portions may be removably fixed to the sensor covering element. For example, the gel portions may be provided as a combined unit of gel portions having one engagement opening formed therein such that the projecting nose or pin may releasably engage with the engagement opening. Accordingly, upon the projecting nose or pin being positioned in alignment with the sensor electrodes, the gel portions are in contact with the sensor electrodes in the non-operational state. In some other examples herein, more than one projecting nose or pin and engagement opening may be formed for removably coupling the gel portions separately with the sensor covering element, e.g., different gel portions that may be individually attached or removed from the sensor covering element. In some alternative examples herein, the projecting nose(s) or pin(s) may be formed on the gel portions, while the sensor covering element may have respective engagement opening(s) formed therein.

[0023] In some other illustrative examples herein, one or more gel portions may be removably or permanently attached to the sensor covering element by a frame with a clamping structure configured for holding at least one gel portion in a mechanical clamping engagement. For example, the frame may be formed by a plurality of wall sections formed on a surface of the sensor covering element facing towards one or more sensor electrodes when the sensor covering element is arranged with respect to the sensor substrate such that the one or more sensor electrodes are covered by the sensor covering element. For example, the sensor covering element may have a frame formed of wall sections that laterally enclose the one or more sensor electrodes in a non-operational state when the sensor covering element covers the one or more sensor electrodes. Furthermore, the frame comprises one or more clamp portions attached to the wall sections by one or more bridging wall sections, the clamp portions being configured such that each clamp portion may permanently or releasably engage a dedicated one of the one or more gel portions. For example, the clamp portions may be formed as at least partially circular or at least partially elliptical wall sections (in a view normal to the surface of the sensor covering element on which the frame is formed) configured for mechanically clamping one or more gel portions within the frame at specified positions in alignment with the one or more sensor electrodes in the non-operational state. The clamp portions may comprise clamping wall sections arranged in a positional relation such that the clamping wall sections mechanically engage one or more gel portions in a clamping relation. In some other illustrative examples herein, one or more gel portions may removably or permanently attached to the sensor covering element by a frame with a mesh structure, e.g., a textile or plastic mesh permanently or releasably attached to wall sections of the frame. Accordingly, the frame is configured for holding at least one gel portion by the mesh structure spanning over one or more gel portions arranged within a space defined by the wall sections of the frame. For example, the frame may be formed by the plurality of wall sections formed on a surface of the sensor covering element facing towards one or more sensor electrodes when the sensor covering element is arranged with respect to the sensor substrate such that the one or more sensor electrodes are covered by the sensor covering element. For example, the sensor covering element may have a polygonal frame formed of wall sections that laterally enclose the one or more sensor electrodes and the one or more gel portions in a non- operational state when the sensor covering element covers the one or more sensor electrodes. Furthermore, the frame comprises the mesh structure which is permanently attached to the wall sections or releasably attached to the wall sections. For example, the mesh structure may be integrally formed with the wall sections, i.e., formed of the same material and integral with the wall sections, or it may be formed as a separate element permanently attached to the wall sections by permanent attachment techniques (e.g., gluing, welding etc.). In case of permanent attachment of the mesh structure to the wall sections, the frame as such may be releasably coupled to the sensor covering element. In case that the mesh structure is releasably attached to the wall sections, the mesh structure may be hooked, temporarily pasted or spanned via elastic spanning elements onto the wall sections, while the wall sections may either be permanently attached on the surface of the sensor covering element or may be integrally formed with the sensor covering element. Accordingly, one or more gel portion may be hold by the frame in a space defined by the wall sections for being in contact with the sensor electrode(s) in the non-operational state.

[0024] In some illustrative embodiments of the first aspect, the sensor covering element may be configured for removable mounting to the card body over the at least one sensor electrode in the non-operational state. Accordingly, the at least one electrode is at least partially covered by the associated gel portion in the non-operational state of the fluid sensor device. The at least one sensor electrode may be easily brought into contact with the gel portion when the fluid sensor device is in the non-operational state. Additionally or alternatively, the sensor covering element may be mounted over the sensor electrode during a calibration process to which the at least one sensor electrode is exposed.

[0025] In accordance with some illustrative examples herein, the sensor covering element may be mountable to the card body so as to completely house the sensor substrate in the non- operational state. Accordingly, the sensor electrode may be protected in the non-operational state, while being kept in appropriate conditions for storing the sensor electrode in the non- operational state.

[0026] In accordance with some illustrative embodiments of the first aspect, the at least one gel portion may comprise at least one of a hydrogel and a jelly-like substance. Accordingly, an appropriate chemical environment may be easily provided by hydrogel and a jelly-like substances which may easily and reliably prepared by a great variety of chemistry. In its explicit illustrative but non-limiting examples herein, the at least one gel portion may comprise at least one of polyacrylacid, polyvinylalcohol, agar-agar, hyaluronic acid, chitosan, heparin, alginate, fibrin, , polyethylene glycol, sodium polyacrylate, acrylate polymers, and copolymers.

[0027] In accordance with some illustrative embodiments of the first aspect, the at least one gel portion may be prepared to further comprise a storage liquid and / or a calibration liquid and / or a disinfectant and / or cleaning liquid. For example, the storage liquid may be one of water, NaCI solution or KCI solution (any of these solutions with low concentration or as saturated solution), and antioxidant, the calibration liquid may be a buffer solution having a predefined pH level, e.g. a pH level of 7 or 4 or 9, and the disinfectant and / or cleaning liquid may comprise distilled water or alcohol. Accordingly, an appropriate chemical environment for storing and / or a calibrating and / or a disinfecting and / or cleaning may be provided.

[0028] In accordance with some embodiments of the first aspect, the sensor substrate may be a flexible substrate, thereby allowing a bendable sensor device. In some illustrative examples herein, the flexible substrate may be formed of a heat resistant material made of polymers, like Polyimide or Polyethylene terephthalate (PET), Polycarbonate and polypropylene adipate, Polyethersulfone. The flexible substrate may have a thickness of at most 800 pm, such as in the range from 100 pm to 800 pm, preferably 300 pm to 800 pm.

[0029] In some embodiments of the first aspect, the at least one sensor electrode may be formed of one of a polyaniline (PANI) electrode, an Ag / AgCI electrode, and a metal electrode, such as an electrode of gold or of a noble metal. Alternatively or additionally, at least one sensor electrode may be formed of an organic or inorganic semiconductor and a conductor, such as Polythiophene, polytriaryamines, polypyrol and other substance.

[0030] Herein, polyaniline (PANi or PANI - previously known as Aniline black in 1862) is the oxidative polymeric product of aniline under acidic conditions, built up from reduced (B — NH — B — NH) and oxidized (B — N — Q=N — ) repeat units. The presence of an — NH group in the polymer backbone makes PANI easily doped / undoped under an acidic or alkaline environment. The protonation / deprotonation phenomenon gave rise to a changing in the electronic conductivity and color of PANI, thus PANI having a wide range of applications especially in industrial and sensor applications. The composite form of PANI (either with metal, metal oxide, or carbonbased materials) has been applied in a number of applications, including in anti-corrosive coatings, energy storage and conversion systems, gas sensors, and electrocatalytic devices. Additionally, PANI has also been widely exploited as a potential material for biosensing and tunable electrical and optical properties. In a redox or enzymatic reaction, PANI plays the role as an effective mediator for electron transfer and it can also be deployed as a matrix for the immobilization of biomolecules. In other words, PANI is a conducting organic material with good environmental stability, moderately high conductivity upon doping with simple protonic acid, lower production costs and easy synthesis compared with other conducting polymers, such as polyphenol and polyethylene. PANI is considered as an air stable organic conducting polymer.

[0031] In accordance with some embodiments of the first aspect, the fluid sensor device may further comprise at least one additional sensor electrode formed on the sensor substrate such that a plurality of sensor electrodes is provided. Herein, the sensor electrodes of the plurality of sensor electrodes is selected of at least one of a PANI-type electrode, an Ag / AgCl-type electrode, and a metal-type electrode. For example, a metal-type electrode may be formed of a noble metal such as silver (Ag) or gold (Au) or a metal of the platinum group such as ruthenium, rhodium, palladium, osmium, iridium, platinum and / or a combination thereof.

[0032] In a second aspect, a method of using the fluid sensor device of the first aspect is provided. In the illustrative embodiments of the second aspect, the method comprises arranging the at least one gel portion on an associated one of the at least one sensor electrode in a storing mode of use of the fluid sensor device and / or a calibrating mode of use of the fluid sensor device. Upon using the fluid sensor device of the first aspect, a reduced settle time and improved long term stability behavior for the fluid sensor device is achieved.

[0033] In some illustrative examples herein, the fluid sensor device may comprise the sensor covering element as described above in accordance with some illustrative embodiments of the first aspect. This fluid sensor device may be subjected to the method of the second aspect, wherein arranging the at least one gel portion on the at least one sensor electrode comprises assembling the sensor covering element to the sensor substrate. The sensor covering element may serve for protecting and / or supplying the at least one gel portion to the sensor electrode(s). For example, the at least one gel portion (or a subset thereof) may be supplied to the sensor electrode and, subsequently, the sensor covering element may be assembled for covering the sensor electrode(s). Alternatively or additionally, the at least one gel portion (or a subset thereof) may be provided to the sensor covering element and, subsequently, the sensor covering element may be assembled for covering the sensor electrode(s).

[0034] For example, the method may further comprise, in the storing mode of use of the fluid sensor device, preparing one or more prepared storing gel portions by supplying storage liquid to one or more gel portions, the arranging of the at least one gel portion comprising arranging the one or more prepared storing gel portions on the associated one of the at least one sensor electrode in the storing mode of use. Accordingly, the at least one sensor electrode may be stored under optimum storing conditions.

[0035] In some examples herein, the method may further comprise performing a first calibration step in the calibrating mode of use, the first calibration step comprising preparing one or more prepared calibrating gel portions by supplying first calibrating liquid to one or more gel portions. Herein arranging the at least one gel portion of the method of the second aspect comprises arranging the one or more prepared calibrating gel portions on the associated one of the at least one sensor electrode in the calibrating mode of use. Furthermore, the method may comprise performing a second calibration step, the second calibration step comprising preparing a second gel portion by supplying a second calibrating liquid to the second gel portion to obtain a prepared second calibrating gel portion, wherein the second calibrating liquid is different from the first calibrating liquid. For example, the difference in the first and second calibrating liquids may be a difference in pH level of the first and second calibrating liquids (e.g., a first pH level in the first calibration step and a different second pH level in the second calibration step). For example, each of the first and second pH level may be one of a pH value selected from pH = 1 to 14. Alternatively, the first and second calibrating liquids may differ in a different physical and / or chemical characteristic associated with a characteristic to be measured. The second calibration step may further comprise arranging the second gel portion as the prepared second calibrating gel portion on the at least one sensor electrode subsequent to the first calibration step.

[0036] In some examples of the second aspect, the calibrating mode of use may be performed after the storing mode of use is performed. Accordingly, the fluid sensor device may be calibrated directly subsequent to the storing mode before entering into operational mode by using the fluid sensor device for measurements.

[0037] In some illustrative embodiments of the second aspect, the method may comprise performing a cleaning and / or disinfecting step, the cleaning and disinfecting step comprising preparing one or more prepared disinfecting and / or cleaning gel portions by supplying a disinfectant and / or cleaning liquid to one or more gel portions. Herein, arranging the at least one gel portion in the method of the second aspect comprises arranging the one or more prepared disinfecting and / or cleaning gel portions on the associated one of the at least one sensor electrode in a disinfecting and / or cleaning mode of use. Accordingly, the fluid sensor device may be cleaned and disinfected.

[0038] In illustrative examples herein, the cleaning and / or disinfecting mode of use may be performed prior to any of the storing mode of use and the calibrating mode of use. Accordingly, contamination of prepared storing gel portions is avoided.

[0039] In some illustrative embodiments of the second aspect, the method may further comprise preparing the at least one gel portion by supplying a chemistry to the gel portion to obtain at least one prepared gel portion prior to arranging the prepared gel portion on the at least one sensor electrode to expose the at least one sensor electrode to a chemical environment defined by the chemistry. The chemistry may comprise one or more chemicals or chemical agents. Herein, arranging the at least one sensor electrode of the second aspect comprises arranging the at least one prepared gel portion on the at least one sensor electrode.

[0040] In some illustrative examples herein, the chemistry may comprise one of a storage liquid, a disinfectant and / or cleaning liquid, and a calibration liquid. For example, the storage liquid may be one of water, a NaCI solution and a saturated KCI solution. The disinfectant and / or cleaning liquid may comprise distilled water or an antioxidant or an alcohol. The calibration liquid may be a buffer solution having a predefined pH level in the range from a pH value of 1 to a pH value of 14, such as a pH level of 7 or 4 or 9, for example.

[0041] In some illustrative examples herein, the method may further comprise repeatedly preparing at least one prepared additional gel portion with different chemistries for sequentially exposing the at least one sensor electrode to different chemical environments. Accordingly, a sequence of cleaning and / or disinfecting and / or calibrating and / or storing processes may be iteratively supplied by the prepared additional gel portion(s) in a non-operational mode of use of the sensor device. For example, different modes of a storage mode, disinfectant mode, cleaning mode, and a calibration mode may be sequentially performed in various permutations. Each one of the storage mode, disinfectant mode, cleaning mode, and a calibration mode may comprise at least one storage step, disinfectant step, cleaning step, and a calibration step, wherein each of the storage step, disinfectant step, cleaning step, and a calibration step comprises a step of preparing at least one prepared additional gel portion with a dedicated chemistry.

[0042] Brief description of the drawings In the drawings, like or same reference numerals among the drawings generally refer to same or like features throughout the different drawings. In addition, the drawings are not necessarily to scale, while emphasis is instead generally placed upon illustrating the principles of the disclosure. Embodiments of the disclosure are now be illustrated for the sake of example only with reference to the following drawings, in which:

[0043] Fig. 1 schematically illustrates a fluid sensor device in accordance with some illustrative embodiments of the present disclosure at an initial stage during a non-operational state of the fluid sensor device;

[0044] Fig 2 schematically illustrates the fluid sensor device of Fig. 1 at a later stage during the non- operational state of the fluid sensor device;

[0045] Fig. 3 schematically illustrates a fluid sensor device in accordance with other illustrative embodiments of the present disclosure in a non-operational state of the fluid sensor device;

[0046] Fig. 4 schematically illustrates a fluid sensor device in accordance with still other illustrative embodiments of the present disclosure in an operational state of the fluid sensor device;

[0047] Fig. 5 schematically illustrates the fluid sensor device of Fig. 4 in a non-operational state of the fluid sensor device;

[0048] Figs. 6a and 6b schematically illustrate two calibration steps in a calibration process of a fluid sensor device in accordance with some illustrative embodiments of the present disclosure;

[0049] Figs. 7a, 7b, and 7c schematically illustrate each a fixation of gel portions to a sensor covering element.

[0050] Detailed description

[0051] In accordance with various illustrative embodiments of the first aspect of the present disclosure a fluid sensor device, as described above, comprises a sensor substrate, at least one sensor electrode formed on the sensor substrate, and at least one gel portion associated with the at least one sensor electrode. In an operational state of the fluid sensor device, a sensor surface of the at least one sensor electrode is exposed to a sample liquid. In a non-operational state of the fluid sensor device, the sensor surface of the at least one sensor electrode is at least partially covered by the associated gel portion.

[0052] With regard to Fig. 1 , some illustrative embodiments of the present disclosure at an initial stage during a non-operational state are described, schematically showing a fluid sensor device 1 in the initial stage. Fig. 2 shows some illustrative embodiments of the present disclosure at a later stage during the non-operational state.

[0053] As schematically shown in Fig. 1 , the fluid sensor device 1 comprises a sensor substrate 2 and three sensor electrodes 4a, 4b and 4c. For example, the sensor electrodes 4a, 4b and 4c may represent various kinds of sensor electrodes. Without limitation and for mere illustration, the sensor electrode 4a may be an electrode such as a polyaniline (PANI) electrode, the sensor electrode 4b may be a reference electrode, e.g. an Ag / AgCI electrode, and the sensor electrode 4c may be a metal electrode, such as a noble metal electrode. Furthermore, although not explicitly illustrated in Fig. 1 , separating wall sections may be formed between two neighboring electrodes for providing dedicated compartments associated with each sensor electrode such that any of the compartments may contain a dedicated fluid without interfering with another of the compartments.

[0054] In special illustrative examples herein, the sensor electrode 4a may be formed as a graphene / polyaniline / polystyrene / nano porous fibers modified electrode for determination of heavy metals, such as lead and cadmium. Alternatively, the sensor electrode 4a may be a polyaniline coated glassy carbon electrode, which in some illustrative applications may be used for virus infection detection, such as the detection of dengue virus infection. Still alternatively, the sensor electrode 4a may be an electrode based on polyaniline thin films deposited on the sensor substrate 2 coated with indium tin oxide (ITO) at the sensor electrode 4a. Herein, polyaniline thin films may be abstained by potentiostatic deposition techniques, applying an electric potential in the range up to 5 volt for a duration in a range to about 200 seconds. An accordingly formed PANI based sensor electrode 4a may be used in some illustrative applications as an electrode of a fluid sensor device for pH monitoring.

[0055] In illustrative examples where the sensor electrode 4b is provided in form of an Ag / AgCI sensor electrode (also referred to as “silver chloride electrode”), such an electrode may be embodied as a reference electrode of the fluid sensor device 1 , the sensor electrode 4b being integrated onto the sensor substrate 2. This does not limit the present disclosure and a reference electrode may be provided separate from the sensor substrate 2 as a connectable module for electrically coupling the connectable module with the fluid sensor device 1 during the operational state of the fluid sensor device 1 . The silver chloride electrode 4b may comprise a metallic silver layer (not illustrated) coated with a thin layer of silver chloride (not illustrated).

[0056] The metal electrode 4c may be a noble metal electrode, such as an electrode comprising a noble metal such as silver (Ag) or gold (Au) or a metal of the platinum group such as ruthenium, rhodium, palladium, osmium, iridium, platinum and / or a combination thereof. For example, a palladium or platinum oxide layer may be formed on the electrode and may be employed in analytical applications using measurements in acidic and base solutions.

[0057] With ongoing reference to Fig. 1 , the fluid sensor device 1 further comprises a single gel portion 6 associated with the plurality of sensor electrodes 4a, 4b and 4c. The single gel portion 6 is dimensioned such that the single gel portion 6 may at least partially cover each of the sensor electrodes 4a, 4b, and 4c as will be described below.

[0058] Referring to Fig. 2, the fluid sensor device 1 is schematically illustrated in a stage after the initial stage shown in Fig. 1 in a non-operational state of the fluid sensor device 1. In particular, Fig. 2 shows the fluid sensor device 1 in a state in which it is not used for measurements, i.e. it is not in the operational state. Herein, the single gel portion 6 is arranged on the sensor electrodes such that surfaces of the sensor electrodes 4a to 4c, i.e. the surface 4as of the sensor electrode 4a, the surface 4bs of the sensor electrode 4b, and the surface 4cs of the sensor electrode 4c, is covered by the single gel portion 6 such that the surfaces 4as, 4bs, 4cs (representing upper surfaces of the sensor electrodes 4a to 4c) are completely covered by the single gel portion 6, while side surfaces of at least some of the sensor electrodes 4a to 4c are not necessarily completely covered or even covered by the single gel portion 6. For example, side surfaces of the sensor electrode 4a may be only partially covered by the single gel portion 6, while side surfaces of the reference electrode 4b may be completely covered by the single gel portion 6 and at least some side surfaces of the sensor electrode 4c may remain uncovered by the single gel portion 6. This however does not impose any limitation on the present disclosure and side surfaces of the sensor electrodes 4a to 4c may be only partially covered or completely covered or remain uncovered or a combination of different possibilities herein. For example, the sensor electrodes 4a to 4c may be completely covered with regard to surfaces exposed to sample liquids in the operational state of the fluid sensor device 1 .

[0059] In accordance with some illustrative embodiments herein, the gel portion 6 may be prepared prior to its arrangement on the sensor electrodes 4a to 4c by supplying an appropriate chemistry to the single gel portion 6. For example, the gel portion 6 may be equipped with a storage liquid or a disinfectant and / or cleaning liquid or a calibration liquid. For example, the storage liquid may be one of water, such as distilled water, a saturated NaCI solution or a saturated KCI (Potassium Chloride Solution) solution. For example, saturated KCI solution helps ensure that the sensor electrode 4b produces fast response times and accurate results. Herein, the saturated KCI solution is a concentrated electrolyte solution used in accordance with some illustrative examples herein to store the sensor electrode 4b as at least one of a pH electrode and a redox electrode when not in use, i.e., in the non-operational mode. Particularly when providing the sensor electrode 4b as a glass electrode, such an electrode needs to be kept moist. If a glass electrode dries out during storage, a regeneration procedure is required to restore the hydrated glass layer and the reference junction in order to make the electrode operable, thereby negatively affecting settle time, measurement speed, calibration and long term stability. For example, preparing the single gel portion 6 with a potassium chloride solution keeps the electrodes 4a to 4c hydrated to maximize electrode performance and extend electrode life for the electrodes 4a to 4c.

[0060] As used in the present disclosure, the term “saturated solution” means a solution that contains the maximum amount of solute that is capable of dissolving.

[0061] In some special illustrative example, the disinfectant and / or cleaning liquid may comprise distilled water or an alcohol or an antioxidant containing solution. For example, the calibration liquid may comprise a buffer solution having a predefined pH level from a pH value in the range from 1 to 14, such as a pH level of 7 or 4 or 9. However, this does not limit the present disclosure and the person skilled in the art will appreciate that the buffer solution may have any predefined pH level appropriate for the calibration of the fluid sensor device, such as any pH value from 1 to 14.

[0062] From the complete lecture of the present disclosure, the person skilled in the art will appreciate that, depending on the intended use of the fluid sensor device in the non-operational stage, at least one of storage, disinfection, cleaning, and calibration may be performed by selecting an appropriate chemistry for preparing the single gel portion 6, possibly repeatedly preparing the single gel portion 6 with appropriate chemistries. For example, a storage liquid may be selected for humidifying or hydrating the sensor electrodes 4a to 4c in the non-operational state of the fluid sensor 1 . Furthermore, the storage liquid may have additional chemistry for keeping the sensor electrodes 4a to 4c under defined condition to ensure proper operation and accuracy of the sensor when being used in the operational state of the fluid sensor 1. The gel portion 6 allows the sensor electrodes 4a, 4b and 4c to be kept hydrated in the non- operational state.

[0063] Upon supplying a disinfectant and / or cleaning liquid to the single gel portion 6, disinfecting and / or cleaning of the fluid sensor device 1 may be achieved. Herein, the single gel portion 6 may be arranged on the sensor electrode 4a to 4b for a predetermined time interval.

[0064] Regarding a calibration of the fluid sensor device 1 , the gel portion 6 may allow to perform a one point calibration when being arranged on the sensor electrodes 4a to 4c after being supplied with a calibration liquid. Furthermore, a two point calibration may be performed when sequentially arranging different single gel portions 6 on the sensor electrodes 4a to 4c after having the gel portion 6 appropriately prepared by the supply of appropriate calibration liquids to the single gel portion 6. Alternatively, differently prepared gel portions 6 having different calibration liquids supplied thereto may be sequentially arranged on the sensor electrode 4a to 4c for performing a sequence of calibration points such as two point calibration, three point calibration, four point calibration, five point calibration and so on.

[0065] In accordance with some illustrative embodiments, selecting an appropriate storage liquid may comprise composing an appropriate chemistry for sensor storage by preparing an aqueous solution having an appropriate chemistry added thereto for allowing an appropriate sensor storage by providing a predefined pH level, chloride concentration and so on to the aqueous solution and supplying the prepared aqueous solution to the single gel portion 6.

[0066] In accordance with some illustrative embodiments of the present disclosure, the single gel portion 6 may comprise a chemical indicator for indicating a chemical characteristic of the hydrogel. For example, a state of the hydrogel may indicate a state of the fluid sensor device 1 such as a change in the pH level or chloride concentration or oxidation level of the sensor electrode such that the chemical indicator in the gel portion 6 may indicate a refreshing and / or disinfecting and / or cleaning and / or calibration of the sensor electrode(s) 4a, 4b, 4c in the course of the non-operational state.

[0067] In accordance with some illustrative embodiments of the present disclosure, the gel portion 6 may comprise a hydrogel and / or a jelly like substance. In some illustrative examples herein, the hydrogel and / or jelly like substance (e.g., on agar-agar basis) may be provided in a permeable pouch or pad or shell, allowing liquid contained in the gel portion 6 to permeate the permeable pouch or pad or shell of the gel portion 6.

[0068] In accordance with the disclosure herein, a hydrogel is represented by a cross linked hydrophilic polymer that does not dissolve in water.

[0069] Referring to Fig. 3, a fluid sensor device 10 in accordance with another illustrative embodiment of the present disclosure is schematically illustrated. As schematically shown in Fig. 3, the fluid sensor device 10 comprises a sensor substrate 12 and three sensor electrodes 14a, 14b and 14c. For example, the sensor electrodes 14a, 14b and 14c may represent various kinds of sensor electrode(s). Without limitation and for mere illustration, the sensor electrode 4a may be an electrode such as a polyaniline (PANI) electrode, the sensor electrode 4b may be a reference electrode, e.g. an Ag / AgCI electrode, and the sensor electrode 4c may be a metal electrode, such as a noble metal electrode. Furthermore, although not explicitly illustrated in Fig. 3, separating wall sections may be formed between two neighboring electrodes for providing dedicated compartments associated with each sensor electrode such that any of the compartments may contain a dedicated fluid without interfering with another of the compartments.

[0070] In special illustrative examples herein, the sensor electrode 14a may be formed as a graphene / polyaniline / polystyrene / nano porous fibers modified electrode for determination of heavy metals, such as lead and cadmium. Alternatively, the sensor electrode 4a may be a polyaniline coated glassy carbon electrode, which in some illustrative applications may be used for virus infection detection, such as the detection of dengue virus infection. Still alternatively, the sensor electrode 14a may be an electrode based on polyaniline thin films deposited on the sensor substrate 12 coated with indium tin oxide (ITO) at the sensor electrode 14a. Herein, polyaniline thin films may be abstained by potentiostatic deposition techniques, applying an electric potential in the range up to 5 volt for a duration in a range to about 200 seconds. An accordingly formed PAN I based sensor electrode 14a may be used in some illustrative applications as an electrode of a fluid sensor device for pH monitoring.

[0071] In illustrative examples where the sensor electrode 14b is provided in form of an Ag / AgCI sensor electrode (also referred to as “silver chloride electrode”), such an electrode may be embodied as a reference electrode of the fluid sensor device 10, the sensor electrode 14b being integrated onto the sensor substrate 12. This does not limit the present disclosure and a reference electrode may be provided separate from the sensor substrate 12 as a connectable module for electrically coupling the connectable module with the fluid sensor device 10 during the operational state of the fluid sensor device 10. The silver chloride electrode 14b may comprise a metallic silver layer (not illustrated) coated with a thin layer of silver chloride (not illustrated).

[0072] The metal electrode 14c may be a noble metal electrode, such as an electrode comprising a noble metal such as silver (Ag) or gold (Au) or a metal of the platinum group such as ruthenium, rhodium, palladium, osmium, iridium, platinum and / or a combination thereof. For example, a palladium or platinum oxide layer may be formed on the electrode and may be employed in analytical applications using measurements in acidic and base solutions.

[0073] With ongoing reference to Fig. 3, the fluid sensor device 10 further comprises a plurality of gel portions 16a, 16b, 16c. Each of the plurality of gel portions 16a, 16b, 16c is associated with a dedicated one of the plurality of sensor electrodes 14a, 14b and 14c. Each of the plurality of gel portions 16a, 16b, 16c is dimensioned such that each of the plurality of gel portions 16a, 16b, 16c may at least partially a dedicated one of the sensor electrodes 14a, 14b, and 14c as will be described below. Fig. 3 schematically illustrates a stage in a non-operational state of the fluid sensor device 10 after the plurality of gel portions 16a, 16b, 16c are arranged on the sensor electrodes 14a, 14b, 14c. In particular, Fig. 3 shows the fluid sensor device 10 in a state in which it is not used for measurements, i.e. it is not in the operational state. Herein, the plurality of gel portions 16a, 16b, 16c is arranged on the sensor electrodes 14a, 14b, 14c such that surfaces of the sensor electrodes 14a to 14c, i.e. the surface as of the sensor electrode 14a, the surface Mbs of the sensor electrode 14b and the surface Mcs of the sensor electrode 14c, is covered by the gel portions 16a to 16c such that the surfaces Mas, Mbs, Mcs (representing upper surfaces of the sensor electrodes 14a to 14c) are completely covered by the gel portions 16a to 16c, while side surfaces of at least some of the sensor electrodes 14a to 14c are not necessarily completely covered or even covered by the gel portions 16a, 16b, 16c. For example, side surfaces of the sensor electrode 14a may be only partially covered by the gel portion 16a, while side surfaces of the reference electrode 14b may be completely covered by the gel portion 16b and at least some side surfaces of the sensor electrode 14c may remain uncovered by the gel portion 16c. This however does not impose any limitation on the present disclosure and side surfaces of the sensor electrodes 14a to 14c may be only partially covered or completely covered or remain uncovered or a combination of different possibilities herein. For example, the sensor electrodes 14a to 14c may be completely covered with regard to surfaces exposed to sample liquids in the operational state of the fluid sensor device 10.

[0074] In accordance with some illustrative embodiments herein, the plurality of gel portions 16a to 16c may be prepared prior to the arrangement of the plurality of gel portions 16a to 16c on the sensor electrodes 14a to 14c by supplying an appropriate chemistry to each of the plurality of gel portions 16a to 16c. For example, each of the plurality of gel portions 16a to 16c may be equipped with a dedicated one of a storage liquid or a disinfectant and / or cleaning liquid or a calibration liquid. For example, the storage liquid may be one of water, such as distilled water, a saturated NaCI solution or a saturated KCI (Potassium Chloride Solution) solution. For example, saturated KCI solution helps ensure that the sensor electrode 4b produces fast response times and accurate results. Herein, the saturated KCI solution is a concentrated electrolyte solution used in accordance with some illustrative examples herein to store the sensor electrode 14b as at least one of a pH electrode and a redox electrode when not in use, i.e., in the non-operational mode. Particularly when providing the sensor electrode 14b as a glass electrode, such an electrode needs to be kept moist. If a glass electrode dries out during storage, a regeneration procedure is required to restore the hydrated glass layer and the reference junction in order to make the electrode operable, thereby negatively affecting settle time, measurement speed, calibration and long term stability. For example, preparing at least one of the plurality of gel portions 16a to 16c with a potassium chloride solution keeps the dedicated one or ones of the electrodes 14a to 14c hydrated to maximize electrode performance and extend electrode life for the dedicated one or ones of the electrodes 14a to 14c.

[0075] In some special illustrative example, the disinfectant and / or cleaning liquid may comprise distilled water or an alcohol or an antioxidant containing solution. For example, the calibration liquid may comprise a buffer solution having a predefined pH level from a pH value in the range from 1 to 14, such as a pH level of 7 or 4 or 9. However, this does not limit the present disclosure and the person skilled in the art will appreciate that the buffer solution may have any predefined pH level appropriate for the calibration of the fluid sensor device, such as any pH value from 1 to 14.

[0076] From a complete lecture of the present disclosure, the person skilled in the art will appreciate that, depending on the intended use of the fluid sensor device in the non-operational stage, at least one of storage, disinfection, cleaning, and calibration may be performed by selecting an appropriate chemistry for preparing plurality of gel portions 16a to 16c, possibly repeatedly preparing the each of the plurality of gel portions 16a to 16c with appropriate chemistries. For example, a storage liquid may be selected for humidifying or hydrating at least one of the sensor electrodes 14a to 14c in the non-operational state of the fluid sensor 10. Furthermore, the storage liquid may have additional chemistry for keeping the dedicated one or ones of the sensor electrodes 14a to 14c under defined condition to ensure proper operation and accuracy of the sensor when being used in the operational state of the fluid sensor 10. The gel portions 16a to 16c allow the sensor electrodes 14a, 14b and 14c to be kept hydrated in the non- operational state.

[0077] Upon supplying a disinfectant and / or cleaning liquid to at least one of the plurality of gel portions 16a to 16c, disinfecting and / or cleaning of the fluid sensor device 10 may be achieved. Herein, the gel portions 16a to 16c may be arranged on dedicated ones of the sensor electrodes 14a to 14b for a predetermined time interval.

[0078] Regarding a calibration of the fluid sensor device 10, at least one of the gel portions 16a to 16c may allow to perform a one point calibration when being arranged on the dedicated one or ones of the sensor electrodes 14a to 14c after being supplied with a calibration liquid. Furthermore, a two point calibration may be performed when sequentially arranging one or more differently prepared gel portions of the plurality of gel portions 16a to 16c on the dedicated one or ones of the sensor electrodes 14a to 14c after having the gel portions 16a to 16c appropriately prepared by the supply of appropriate calibration liquids to the dedicated one or ones of the gel portions 16a to 16c. Alternatively, one or more differently prepared of the gel portions 16a to 16c having different calibration liquids supplied thereto may be sequentially arranged on the dedicated one or ones of the sensor electrodes 14a to 14c for performing a sequence of calibration points such as two point calibration, three point calibration, four point calibration, five point calibration and so on at least one of the sensor electrodes 14a to 14c.

[0079] In accordance with some illustrative embodiments, selecting an appropriate storage liquid may comprise composing an appropriate chemistry for sensor storage by preparing an aqueous solution having an appropriate chemistry added thereto for allowing an appropriate sensor storage by providing a predefined pH level, chloride concentration and so on to the aqueous solution and supplying the prepared aqueous solution to at least one of the plurality of gel portions 16a to 16c.

[0080] In accordance with some illustrative embodiments of the present disclosure, at least one of the plurality of gel portions 16a to 16c may comprise a chemical indicator for indicating a chemical characteristic of the hydrogel. For example, a state of the hydrogel may indicate a state of the fluid sensor device 10 such as a change in the pH level or chloride concentration or oxidation level of the sensor electrode such that the chemical indicator in at least one of the plurality of gel portions 16a to 16c may indicate a refreshing and / or disinfecting and / or cleaning and / or calibration of the dedicated one or ones of the sensor electrodes 14a, 14b, 14c in the course of the non-operational state.

[0081] In accordance with some illustrative embodiments of the present disclosure, at least one of the plurality of gel portions 16a to 16c may comprise a hydrogel and / or a jelly like substance. In some illustrative examples herein, the hydrogel and / or jelly like substance (e.g., on agar- agar basis) may be provided in a permeable pouch or pad or shell, allowing liquid contained in the dedicated on of the gel portions 16a to 16c to permeate the permeable pouch or pad or shell of the dedicated one of the gel portions 16a to 16c.

[0082] Referring to Fig. 4, a fluid sensor device 20 in accordance with other illustrative embodiments of the present disclosure is schematically illustrated in an operational state of the fluid sensor 20. The fluid sensor 20 comprises a sensor substrate 22 and a plurality of sensor electrodes 24a, 24b, and 24c formed on the sensor substrate 22. The sensor substrate 22 is integrated into a support frame 25. The support frame 25 may have a recess formed in a surface 25s thereof, the sensor substrate 22 being accommodated into the recess 25s such that a surface 22s of the sensor substrate 22 (the surface 22s on which the plurality of sensor electrodes 24a to 24c is formed) is formed flush with the surface of the support frame 25 in which the recess is formed (i.e., the surface 22s and the surface 25s forms a continuous planar surface). Alternatively, the sensor substrate 22 may have a coating on the surface 22s embedding the sensor electrodes 24a to 24c into the coating such that upper surfaces 24as, 24bs, 24cs of the sensor electrodes 24a to 24c are exposed and the exposed surfaces 24as, 24bs, 24cs of the sensor electrodes 24a to 24 c are flush with the surface 25s of the support frame 25 in which the recess is formed (i.e. , the surface 22s is recessed with respect to the surface 25s). In the state illustrated in Fig. 4 of the fluid sensor device 20, the sensor device 20 may be employed for measurements and the sensor electrodes 24a to 24c may be exposed to a sample liquid.

[0083] In accordance with some illustrative examples of the present disclosure, the support frame 25 may be a card body of a smart card and, accordingly, a compact fluid sensor device 20 may be provided. Alternatively, the support frame 25 may be part of a housing structure mating with a covering element 27 (see Fig. 5) for housing the sensor substrate 22 with the sensor electrodes 24a to 24c into a housing upon assembling the covering element 27 to the support frame 25. Accordingly, the sensor substrate 22 with the sensor electrodes 24a to 24c may be completely housed into a housing 28 composed of the support frame 25 in mating connection with the covering element 27 as illustrated in Fig. 5 where the fluid sensor device 20 is in a non-operational state.

[0084] Referring to Fig. 5, the fluid sensor device 20 as shown in the non-operational state (i.e., the state in which the covering element 27 is assembled to the support frame 25, e.g. a card body of a sensor card such as a smart card optionally comprising further electric and / or electronic modules integrated into the smartcard). The sensor covering element 27 may be equipped with at least one gel portion, such as a dedicated gel portion 26a, 26b, 26c associated with each sensor electrode of the sensor electrodes 24a to 24c or, alternatively, with a single gel portion (not illustrated) corresponding to the single gel portion 6 as described above with regard to Figs. 1 and 2. The gel portions 26a, 26b and 26c are arranged on the sensor electrodes 24a to 24c as schematically illustrated in Fig. 5 once the fluid sensor device 20 is brought into the non-operational state.

[0085] With regard to Figs. 6a and 6b, a sequence of process steps in a specific process mode will be described in accordance with some illustrative embodiments of the present disclosure. Figs. 6a and 6b each show the fluid sensor device 20 in the non-operational state but in different process step of a specific process mode. Accordingly, reference numerals of Figs. 6a and 6b indicate same features as described with respect to Figs. 4 and 5 above, the disclosure of which is incorporated by reference in its entirety, , while similar reference numerals with respect to Fig. 1 to 3 possibly denote similar features when appropriate, so that the teaching regarding a feature described with respect to Fig. 1 to 3 may transfer in a straightforward manner to a feature designates with like reference numeral in Figs. 6a to 6b. As shown in Figs. 6a and 6b, the fluid sensor device 20 comprises the housing 28 which houses the sensor substrate 22 with the sensor electrodes 24a to 24c and at least one gel portion of the illustrated gel portions 26a to 26c.

[0086] From a complete lecture of the present disclosure, the person skilled in the art will appreciate that, depending on the intended use of the fluid sensor device 20 in the non-operational stage, at least one process mode out of storage mode, disinfection mode, cleaning mode, and calibration mode may be performed for implementing an according function out of at least one of a storage function, disinfection function, cleaning function, and calibration function. A specific process mode may be implemented by selecting an appropriate chemistry for preparing plurality of gel portions 26a to 26c, possibly repeatedly preparing the each of the plurality of gel portions 26a to 26c with appropriate chemistries suitable for realizing the specific process mode.

[0087] In a storage mode of the fluid sensor device 20, a storage liquid may be selected for humidifying or hydrating at least one of the sensor electrodes 24a to 24c in the non-operational state of the fluid sensor 20, for example. In some special but non-limiting examples herein, the storage liquid may have additional chemistry for keeping the dedicated one or ones of the sensor electrodes 24a to 24c under defined condition to ensure proper operation and accuracy of the sensor when being used in the operational state of the fluid sensor 20. The gel portions 26a to 26c allow the sensor electrodes 24a, 24b and 24c to be kept hydrated in the non- operational state.

[0088] In a disinfecting mode of the fluid sensor device 20, a disinfecting liquid may be supplied to at least one of the plurality of gel portions 26a to 26c such that a disinfection of at least one of the sensor electrodes 24a to 24c of the fluid sensor device 20 may be achieved. Herein, the at least one of the gel portions 26a to 26c may be arranged on dedicated one or ones of the sensor electrodes 24a to 24b for a predetermined time interval.

[0089] In a cleaning mode of the fluid sensor device 20, a cleaning liquid may be supplied to at least one of the plurality of gel portions 26a to 26c such that a cleaning of at least one of the sensor electrodes 24a to 24c of the fluid sensor device 20 may be achieved. Herein, the at least one of the gel portions 26a to 26c may be arranged on dedicated one or ones of the sensor electrodes 24a to 24b for a predetermined time interval.

[0090] In a calibration mode of the fluid sensor device 20, at least one of the gel portions 26a to 26c may allow to perform a one point calibration when being arranged on the dedicated one or ones of the sensor electrodes 24a to 24c after a calibration liquid is supplied to the one ore more gel portions. The calibration mode may be an one point calibration mode, a two point calibration mode and so on, generally an n point calibration mode with n being an integer n > 0.

[0091] For example, the one point calibration mode comprises a single calibration step in which at least one of the sensor electrodes 24a to 24c (that is the at least one sensor electrode intended for calibration) is exposed to an according one of the gel portions 26a to 26b in Fig. 6a, the according gel portion(s) being prepared with a dedicated calibration liquid such that the one point calibration may be performed. Herein, the one point calibration mode may be illustrated with respect to a single calibration step as shown in Fig. 6a. In particular, the one point calibration mode terminates after the stage shown in Fig. 6a without a subsequent calibration step according to Fig. 6b being shown.

[0092] In some illustrative examples, the calibration mode may comprise a two point calibration mode. The two point calibration mode comprises two calibration step which may be sequentially performed by sequentially arranging one or more differently prepared gel portions of the plurality of gel portions 26a to 26c on a dedicated one or dedicated ones of the sensor electrodes 24a to 24c after having the gel portions 26a to 26c appropriately prepared. Herein, one or more gel portions may be prepared by supplying appropriate first calibration liquid(s) to the dedicated one or ones of the gel portions 26a to 26c in a first calibration step shown in Fig. 6a and subsequently the one or more gel portions being prepared by supplying appropriate second calibration liquid(s) to the dedicated one or ones of the gel portions 26a’, 26b’, and 26c’ in a second calibration step, as shown in Fig. 6b. That is, one or more of the gel portions 26a to 26c having different calibration liquids supplied thereto in the first calibration step may be subsequently followed by the corresponding one or more of the gel portions now being subjected to the second calibration liquid in the second calibration step, resulting in the corresponding one or more of the gel portions 26a’, 26b’, and 26c’. Herein, one or more of the gel portions 26a to 26c in the first calibration step of Fig. 6a and the corresponding one of the gel portions 26a’ to 26c’ in the second calibration step of Fig. 6b may are sequentially arranged on the dedicated one or ones of the sensor electrodes 24a to 24c for performing the sequence of calibration steps in the two point calibration mode. Upon iteratively performing a sequence of a number of calibration steps, any multi-point calibration may be achieved, such as two point calibration, three point calibration, four point calibration, five point calibration and so on.

[0093] In accordance with some illustrative embodiments, selecting an appropriate storage liquid may comprise composing an appropriate chemistry for sensor storage by preparing an aqueous solution having an appropriate chemistry added thereto for allowing an appropriate sensor storage by providing a predefined pH level, chloride concentration and so on to the aqueous solution and supplying the prepared aqueous solution to at least one of the plurality of gel portions 26a to 26c.

[0094] In accordance with some illustrative embodiments of the present disclosure, at least one of the plurality of gel portions 26a to 26c may comprise a chemical indicator for indicating a chemical characteristic of the hydrogel. For example, a state of the hydrogel may indicate a state of the fluid sensor device 20 such as a change in the pH level or chloride concentration or oxidation level of the sensor electrode such that the chemical indicator in at least one of the plurality of gel portions 26a to 26c may indicate a refreshing and / or disinfecting and / or cleaning and / or calibration of the dedicated one or ones of the sensor electrodes 24a, 24b, 24c in the course of the non-operational state.

[0095] In accordance with some illustrative embodiments of the present disclosure, at least one of the plurality of gel portions 26a to 26c may comprise a hydrogel and / or a jelly like substance. In some illustrative examples herein, the hydrogel and / or jelly like substance (e.g., on agar- agar basis) may be provided in a permeable pouch or pad or shell, allowing liquid contained in the dedicated on of the gel portions 26a to 26c to permeate the permeable pouch or pad or shell of the dedicated one of the gel portions 26a to 26c.

[0096] With ongoing reference to Figs. 6a and 6b, a sequence of different process modes will be described in accordance with some illustrative embodiments of the present disclosure, where Figs. 6a and 6b each show the fluid sensor device 20 in the non-operational state but in different process modes selected from storage mode, disinfection mode, cleaning mode, and calibration mode may be sequentially performed for implementing an according sequence of functions out of storage function, disinfection function, cleaning function, and calibration function.

[0097] In some illustrative embodiments herein, the fluid sensor device 20 shown in Fig. 6a may be subjected to a first process mode selected from storage mode, disinfection mode, cleaning mode, and calibration mode. This first process mode may be one of the selected from storage mode, the disinfection mode, the cleaning mode, and the calibration mode described above in the context of Fig. 6a and / or 6b. Subsequently, a second process mode selected from storage mode, disinfection mode, cleaning mode, and calibration mode may be performed resulting in the fluid sensor device 20 of Fig. 6b, the second process mode being different from the first process mode. For example, the first and second process modes may be different with respect to one or more sensor electrodes of the sensor electrodes subjected to the process modes. Additionally or alternatively, the first and second process modes may be different with respect to one or more process steps performed in the process modes, i.e., the first and second process modes may differ in the number of process steps performed in the process modes.

[0098] In some illustrative examples, the first and second process modes may be different with respect to the process functions to be implemented by the first and second process modes.

[0099] In some special but non-limiting examples herein, the first process mode may be a cleaning mode and the second process mode may be a storage mode or vice versa.

[0100] In some special but non-limiting examples herein, the first process mode may be a disinfecting mode and the second process mode may be a cleaning mode or vice versa.

[0101] In some special but non-limiting examples herein, the first process mode may be a disinfecting mode and the second process mode may be a storage mode or vice versa.

[0102] In some special but non-limiting examples herein, the first process mode may be a disinfecting mode and the second process mode may be a calibration mode or vice versa.

[0103] In some special but non-limiting examples herein, the first process mode may be a storage mode and the second process mode may be a calibration mode or vice versa.

[0104] In some special but non-limiting examples herein, the first process mode may be a cleaning mode and the second process mode may be a calibration mode or vice versa.

[0105] In some special but non-limiting examples herein, the second process mode may be followed by at least one additional third process mode, wherein any two directly subsequent process modes being different process modes. For example, a cleaning mode may be followed by a storage mode which in turn is followed by a calibration mode (and without limitation any permutation thereof), optionally followed by one or more different process mode selected from cleaning mode, storage mode, calibration mode, and disinfection mode.

[0106] In some special but non-limiting examples herein, the first process mode may be a calibrating mode and the second process mode may be a cleaning mode and the third process mode may be another calibrating mode and so on. That is, calibrating mode and cleaning mode may be performed in an alternating sequence.

[0107] In general, any sequence of process modes may be performed, each process mode comprising preparing at least one prepared gel portion by supplying at least one chemistry to one or more gel portions of a fluid sensor device, e.g., the fluid sensor device 20, and subsequently arranging the at least one prepared gel portion on the dedicated one or dedicated ones of the at least one sensor electrode to expose the dedicated one or dedicated ones of the at least one sensor electrode to a chemical environment defined by the at least one chemistry. For example, the at least one chemistry may comprises at least one of a storage liquid, a disinfectant and / or cleaning liquid, and a calibration liquid.

[0108] For example, the sequence of process modes may comprise repeatedly or iteratively preparing a prepared iterative gel portion differing by at least one chemistry for sequentially exposing the dedicated one or dedicated ones of the at least one sensor electrode to different chemical environments.

[0109] With regard to the Fig. 1 to 6b above, illustrative embodiments are disclosed showing a fluid sensor device (1 ; 10; 20), comprising a sensor substrate (2; 12; 22), at least one sensor electrode (4a, 4b, 4c; 14a, 14b, 14c; 24a, 24b, 24c) formed on the sensor substrate (2; 12; 22), and at least one gel portion (6; 16a, 16b, 16c; 26a, 26b, 26c) associated with the at least one sensor electrode (4a, 4b, 4c; 14a, 14b, 14c; 24a, 24b, 24c). The at least one sensor electrode (4a, 4b, 4c; 14a, 14b, 14c; 24a, 24b, 24c) has a sensor surface (4as, 4bs, 4cs; as, Mbs, Mcs; 24as, 24bs, 24cs) for exposure to a sample liquid in an operational state of the fluid sensor device (1 ; 10; 20) and the sensor surface (4as, 4bs, 4cs; Mas, Mbs, Mcs; 24as, 24bs, 24cs) of the at least one sensor electrode (4a, 4b, 4c; 14a, 14b, 14c; 24a, 24b, 24c) is at least partially covered by the associated gel portion (6; 16a, 16b, 16c; 26a, 26b, 26c) in an non-operational state of the fluid sensor device (1 ; 10; 20).

[0110] With respect to Fig. 7a to 7c, a fixation structure of at least one gel portion to a covering element comprising at least one of a hydrogel clip, a plastic frame with clamping and a plastic frame with mesh is now be described. Herein at least one gel portion is reliably mounted to a sensor covering element so as to be in contact with at least one sensor electrode on a sensor substrate in a non-operational state of the at least one sensor electrode in which the sensor covering is arrange with respect to the sensor substrate so as to cover the at least one electrode. Accordingly, the at least one sensor electrode may be exposed to the at least one gel portion in the non-operational state.

[0111] Referring to Fig. 7a and in accordance with some illustrative embodiments, a sensor covering element 37 is shown, having gel portions 36a, 36b, 36c arranged thereon. The sensor covering 37 of Fig. 7a may correspond to the sensor cover 27 described above, the disclosure of which is incorporated by reference in its entirety. Furthermore, the gel portions 36a, 36b, 36c may correspond to any of the gel portions 16a, 16b, 16c and 26a, 26b, 26c as described above, the disclosure of which is incorporated in its entirety. Although three gel portions 36a, 36b, 36c are illustrated in Fig. 7a, this does not impose any limitation and a single gel portion (not illustrated) in correspondence with the gel portion 6 as described above (the disclosure of which is incorporated in its entirety) or only two gel portions (not illustrated) or more than three gel portions (not illustrated) may be implemented instead.

[0112] In the non-operational state, the gel portions 36a, 36b, 36c may be in contact with respective sensor electrodes (not illustrated, but in analogy to the embodiments with the sensor electrodes 4a, 4b, 4c or 14a, 14b, 14c or 24a, 24b, 24c as described above) when the sensor covering element 37 is arranged with respect to the sensor substrate (not illustrated, but in analogy to the embodiments with the substrate 2 or 12 or 22 as described above) such that the sensor electrodes are covered by the sensor covering element 37.

[0113] With ongoing reference to Fig. 7a, the sensor covering element 37 may have a fixation structure 31 comprising one or more projecting noses or pins 31 a, 31 b, 31 c, 31 d formed on a surface region of the sensor covering element 37 facing towards the sensor electrode (not illustrated) in the non-operational state such that the fixation structure 31 faces towards the sensor electrodes (not illustrated) in the non-operational state. The projecting noses or pins 31a, 31 b, 31c, 31 d may be configured for mechanical engagement with the gel portions 36a, 36b, 36c such that the gel portions 36a, 36b, 36c may be removably fixed to the sensor covering element 37. For example, the gel portions 36a, 36b, 36c have engagement openings formed therein such that the projecting noses or pins 31 a, 31 b, 31 c, 31 d releasably engage with the engagement openings. Accordingly, upon the projecting noses or pins 31a, 31 b, 31 c, 31 d being positioned in alignment with the sensor electrodes (not illustrated), the gel portions 36a, 36b, 36c are in contact with the sensor electrodes (not illustrated) in the non-operational state.

[0114] Although Fig. 7a shows an embodiment in which the projection noses or pins 31 a, 31 b, 31 c, 31 d are formed on the sensor covering element 37, the projecting nose or pin may alternatively be formed on the gel portions 36a, 36b, 36c, while the sensor covering element 37 may have respective engagement opening formed therein.

[0115] Referring to Fig. 7b and in accordance with some illustrative embodiments, a sensor covering element 47 is shown, having gel portions 46a, 46b, 46c arranged thereon. The sensor covering 47 of Fig. 7b may correspond to the sensor cover 27 described above, the disclosure of which is incorporated by reference in its entirety. Furthermore, the gel portions 46a, 46b, 46c may correspond to any of the gel portions 16a, 16b, 16c and 26a, 26b, 26c as described above, the disclosure of which is incorporated in its entirety. Although three gel portions 46a, 46b, 46c are illustrated in Fig. 7b, this does not impose any limitation and a single gel portion (not illustrated) in correspondence with the gel portion 6 as described above (the disclosure of which is incorporated in its entirety) or only two gel portions (not illustrated) or more than three gel portions (not illustrated) may be implemented instead.

[0116] In the non-operational state, the gel portions 46a, 46b, 46c may be in contact with respective sensor electrodes (not illustrated, but in analogy to the embodiments with the sensor electrodes 4a, 4b, 4c or 14a, 14b, 14c or 24a, 24b, 24c as described above) when the sensor covering element 47 is arranged with respect to the sensor substrate (not illustrated, but in analogy to the embodiments with the substrate 2 or 12 or 22 as described above) such that the sensor electrodes are covered by the sensor covering element 47.

[0117] With ongoing reference to Fig. 7b, the gel portions 46a, 46b, 46c are removably or permanently attached to the sensor covering element by a frame 42 with a fixations structure 41 formed as a clamping structure configured for holding the gel portions 46a, 46b, 46c in a mechanical clamping engagement. For example, the frame 42 is formed by a plurality of wall sections formed on a surface of the sensor covering element 47 facing towards one or more sensor electrodes (not illustrated, but in analogy to the embodiments with the sensor electrodes 4a, 4b, 4c or 14a, 14b, 14c or 24a, 24b, 24c as described above) when the sensor covering element 47 is arranged with respect to the sensor substrate (not illustrated, but in analogy to the embodiments with the substrate 2 or 12 or 22 as described above) such that the sensor electrodes (not illustrated) are covered by the sensor covering element 47.

[0118] In illustrative examples and as shown in Fig. 7b, the frame 42 is formed of wall sections that laterally enclose the sensor electrodes (not illustrated) in a non-operational state when the sensor covering element 47 covers the sensor electrodes (not illustrated). Furthermore, the frame 42 comprises clamp portions 44a, 44b, 44c attached to the wall sections by one or more bridging wall sections 45. The clamp portions 44a, 44b, 44c are configured such that each of the clamp portions 44a, 44b, 44c permanently or releasably engage a dedicated one of the gel portions 46a, 46b, 46c. For example, the clamp portions may be formed as at least partially circular or at least partially elliptical wall sections (in the view normal to the surface of the sensor covering element 47 as shown in Fig. 7b) configured for mechanically clamping one or more gel portions within the frame at specified positions in alignment with the sensor electrodes (not illustrated) in the non-operational state. The clamp portions 44a, 44b, 44c comprise clamping wall sections of circular or elliptical shape arranged in a positional relation such that the clamping wall sections mechanically engage the gel portions 46a, 46b, 46c in a clamping relation. Although Fig. 7b explicitly shows clamp portions 44a, 44b, 44c of elliptical shape, this does not impose any limitation onto the present disclosure. Any polygonal or circular shape may be employed instead. Furthermore, a combination of different shapes for different gel portions may be used and / or partial circular or elliptical shapes may be used.

[0119] Referring to Fig. 7c and in accordance with some illustrative embodiments, a sensor covering element 57 is shown, having gel portions 56a, 56b, 56c arranged thereon. The sensor covering 57 of Fig. 7c may correspond to the sensor cover 27 described above, the disclosure of which is incorporated by reference in its entirety. Furthermore, the gel portions 56a, 56b, 56c may correspond to any of the gel portions 16a, 16b, 16c and 26a, 26b, 26c as described above, the disclosure of which is incorporated in its entirety. Although three gel portions 56a, 56b, 56c are illustrated in Fig. 7c, this does not impose any limitation and a single gel portion (not illustrated) in correspondence with the gel portion 6 as described above (the disclosure of which is incorporated in its entirety) or only two gel portions (not illustrated) or more than three gel portions (not illustrated) may be implemented instead.

[0120] In the non-operational state, the gel portions 56a, 56b, 56c may be in contact with respective sensor electrodes (not illustrated, but in analogy to the embodiments with the sensor electrodes 4a, 4b, 4c or 14a, 14b, 14c or 24a, 24b, 24c as described above) when the sensor covering element 57 is arranged with respect to the sensor substrate (not illustrated, but in analogy to the embodiments with the substrate 2 or 12 or 22 as described above) such that the sensor electrodes are covered by the sensor covering element 57.

[0121] With ongoing reference to Fig. 7c, the gel portions 56a, 56b, 56c are removably or permanently attached to the sensor covering element 57 by a fixation structure 51 comprising a frame 52 with a mesh structure 54, e.g., a textile or plastic mesh permanently or releasably attached to wall sections of the frame 52. Accordingly, the frame 52 is configured for holding the gel portions 56a, 56b, 56c by the mesh structure 54 spanning over the gel portions 56a, 56b, 56c arranged within a space defined by the wall sections of the frame 52.

[0122] In some illustrative examples and as shown in Fig. 7c, the frame 52 comprises a plurality of wall sections formed on a surface of the sensor covering element 57 facing towards sensor electrodes (not illustrated) when the sensor covering element 57 is arranged with respect to the sensor substrate (not illustrated) such that the sensor electrodes (not illustrated) are covered by the sensor covering element 57. For example, the sensor covering element 57 may have a polygonal frame formed of wall sections that laterally enclose the sensor electrodes (not illustrated) and the gel portions 56a, 56b, 56c in a non-operational state when the sensor covering element 57 covers the sensor electrodes (not illustrated). Furthermore, the frame 52 comprises the mesh structure 54 which is permanently attached to the wall sections or releasably attached to the wall sections. For example, the mesh structure 54 may be integrally formed with the wall sections, i.e., formed of the same material and integral with the wall sections of the frame 52, or it may be formed as a separate element permanently attached to the wall sections of the frame 52 by permanent attachment techniques (e.g., gluing, welding etc.). In case of permanent attachment of the mesh structure 54 to the wall sections of the frame 52, the frame 52 as such may be releasably coupled to the sensor covering element 57. In case that the mesh structure 54 is releasably attached to the wall sections of the frame 52, the mesh structure 54 may be hooked, temporarily pasted or spanned via elastic spanning elements (not illustrated) onto the wall sections of the frame 52, while the wall sections of the frame 52 may either be permanently attached on the surface of the sensor covering element 57 or may be integrally formed with the sensor covering element 57. Accordingly, the gel portions 56a, 56b, 56c may be hold by the frame 52 in a space defined by the wall sections of the frame 52 for being in contact with the sensor electrodes (not illustrated) in the non-operational state.

[0123] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. “Approximately” as applied to a particular value of a range applies to both values, and unless otherwise dependent on the precision of the instrument measuring the value, may indicate + / - 10% of the stated value(s).

[0124] It should be understood that the terminology used herein is for the purpose of describing the disclosed structures and methods and is not intended to be limiting. For example, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Additionally, as used herein, the terms "comprises" "comprising", “includes” and / or “including” specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, as used herein, terms such as "right", "left", "vertical", "horizontal", "top", "bottom", "upper", "lower", “under”, "below", "underlying", "over", "overlying", “parallel”, “perpendicular”, etc., are intended to describe relative locations as they are oriented and illustrated in the drawings (unless otherwise indicated) and terms such as “touching”, “in direct contact”, "abutting", “directly adjacent to”, “immediately adjacent to”, etc., are intended to indicate that at least one element physically contacts another element (without other elements separating the described elements). The term “laterally” is used herein to describe the relative locations of elements and, more particularly, to indicate that an element is positioned to the side of another element as opposed to above or below the other element, as those elements are oriented and illustrated in the drawings. For example, an element that is positioned laterally adjacent to another element will be beside the other element, an element that is positioned laterally immediately adjacent to another element will be directly beside the other element, and an element that laterally surrounds another element will be adjacent to and border the outer sidewalls of the other element. The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.

[0125] The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

CLAIMS1 . A fluid sensor device, preferably a liquid sensor device such as a water sensor device, comprising: a sensor substrate; at least one sensor electrode formed on the sensor substrate, the at least one sensor electrode having a sensor surface for exposure to a sample liquid in an operational state of the fluid sensor device; and at least one gel portion associated with the at least one sensor electrode, wherein the sensor surface of the at least one sensor electrode is at least partially covered by the associated gel portion in a non-operational state of the fluid sensor device.

2. The fluid sensor device of claim 1 , wherein the fluid sensor device is provided as a sensor card having a card body with a recess into which the sensor substrate is accommodated.

3. The fluid sensor device of claim 1 or 2, further comprising a sensor covering element which is mountable to the sensor substrate so as to at least partially house the sensor substrate in the non-operational state.

4. The fluid sensor device of claim 3, wherein the sensor covering element is equipped with the at least one gel portion, and wherein the sensor covering element comprises a fixation structure of the at least one gel portion in the covering element comprising at least one of a hydrogel clip, a plastic frame with clamping and a plastic frame with mesh.

5. The fluid sensor device of claim 3 or 4 in combination with claim 2, wherein the sensor covering element is configured for removable mounting to the card body over the at least one sensor electrode in the non-operational state.

6. The fluid sensor device of one of claims 1 to 5, wherein the at least one gel portion comprises at least one of a hydrogel and a jelly-like substance.

7. The fluid sensor device of one of claims 1 to 6, wherein the at least one gel portion is prepared to further comprise a storage liquid and / or a calibration liquid and / or a disinfectants and / or cleaning liquid.

8. The fluid sensor device of claim 7, wherein the storage liquid is one of water, a disinfectant liquid, NaCI solution or KCI solution, and antioxidant, and the calibration liquid is a buffer solution having a predefined pH value.

9. The fluid sensor device of one of claims 1 to 8, wherein the sensor substrate is a flexible substrate.

10. The fluid sensor device of one of claims 1 to 9, wherein the at least one sensor electrode is formed of one of a PANI electrode, an Ag / AgCI electrode, an electrode comprising an organic or inorganic semiconductor and a metal, and a metal electrode.11 . The fluid sensor device of one of claims 1 to 10, further comprising at least one additional sensor electrode formed on the sensor substrate such that a plurality of sensor electrodes is provided, the sensor electrodes of the plurality of sensor electrodes being selected of at least one of a PANI-type electrode, an Ag / AgCl-type electrode, and a metal-type electrode, e.g., formed of a noble metal.

12. Method of using the fluid sensor device of one of claims 1 to 11 , the method comprising: arranging the at least one gel portion on an associated one of the at least one sensor electrode in a storing mode of use of the fluid sensor device and / or a calibrating mode of use of the fluid sensor device.

13. The method of claim 11 using the fluid sensor device of claim 3 in combination with one of claims 1 , 2 and 4 to 10 subjected to the method, wherein arranging the at least one gel portion on the at least one sensor electrode comprises assembling the sensor covering element to the sensor substrate.

14. The method of claim 12 or 13, further comprising in the storing mode of use, preparing one or more prepared storing gel portions by supplying storage liquid to one or more gel portions, wherein arranging the at least one gel portion comprises arranging the one or more prepared storing gel portions on the associated one of the at least one sensor electrode in the storing mode of use.

15. The method of claim 12 or 13, further comprising performing a first calibration step in the calibrating mode of use, the first calibration step comprising preparing one or more prepared calibrating gel portions by supplying first calibrating liquid to one or more gel portions, wherein arranging the at least one gel portion comprises arranging the one or more prepared calibrating gel portions on the associated one of the at least one sensor electrode in the calibrating mode of use.

16. The method of claim 15, further comprising performing a second calibration step, the second calibration step comprising preparing a second gel portion by supplying a second calibrating liquid to the second gel portion to obtain a prepared second calibrating gel portion, wherein the second calibrating liquid is different from the first calibrating liquid, and arranging the second gel portion as the prepared second calibrating gel portion on the at least one sensor electrode subsequent to the first calibration step.

17. The method of claim 15 or 16 in combination with claim 14, wherein the calibrating mode of use is performed after the storing mode of use is performed.

18. The method of one of claims 12 to 17, further comprising performing a cleaning and / or disinfecting step, the cleaning and disinfecting step comprising preparing one or more prepared disinfecting and / or cleaning gel portions by supplying a disinfectant and / or cleaning liquid to one or more gel portions, wherein arranging the at least one gel portion comprises arranging the one or more prepared disinfecting and / or cleaning gel portions on the associated of the at least one sensor electrode in a disinfecting and / or cleaning mode of use.

19. The method of claim 18, wherein the cleaning and / or disinfecting mode of use is performed prior to any of the storing mode of use and the calibrating mode of use.

20. The method of claim 12, further comprising preparing the at least one gel portion by supplying a chemistry to the gel portion to obtain at least one prepared gel portion prior to arranging the prepared gel portion on the at least one sensor electrode to expose the at least one sensor electrode to a chemical environment defined by the chemistry.

21. The method of claim 20, wherein the chemistry comprises one of a storage liquid, a disinfectant and / or cleaning liquid, and a calibration liquid.

22. The method of claim 20 or 21 , further comprising repeatedly preparing at least one prepared additional gel portion with different chemistries for sequentially exposing the at least one sensor electrode to different chemical environments.

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