BIOCHEMICAL TEST CHIP

The present disclosure provides a biochemical test chip, including an electrode unit and a protective layer. The protective layer is electrically connected to the electrode unit. The protective layer is configured to oxidize the electrode unit after the electrode unit receives an electron or reduce the electrode unit after the electrode unit loses an electron. There is a potential difference (Ecell0) between the protecting layer and the electrode unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefits of Taiwan Patent Application No. 109141392, filed on Nov. 25, 2020, which is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present application relates to a biochemical test chip for use in medical measurement, particularly to a biochemical test chip including a protective layer.

BACKGROUND

In-vitro medical measurement plays a vital role in today's medical industry; by qualitatively and quantitatively measuring biological fluids changes, it provides index information for rapid diagnosis and treatment of diseases. The use of biochemical test chips has become a standard technique for medical or biochemical testing.

Conventional biochemical test chips have at least two electrodes. After loading the specimen into the biochemical test chip's reaction zone, the specimen's electrochemical properties can be measured using said two electrodes. For most electrochemical test strips, a reactive layer reacts with a specimen, and the electrochemical properties of the specimen are analyzed by electrochemical means. However, the composition of the reactive layer is extremely sensitive to environmental factors such as temperature, humidity, and oxygen level. For example, the reactive layer's conductive medium is susceptible to oxidation with oxygen in the air. This oxidation reaction can easily cause inaccurate measurement of electrochemical test strips, leading to the short service life of conventional electrochemical test strips.

To address the effect of environmental factors on electrochemical test strips, electrochemical test strips are often stored in containers with desiccant, protected from light, and relatively sealed to avoid damage to electrochemical test strips. However, when the user opens the container to retrieve the electrochemical test strips, the container's internal environment will change when the container is opened, and hence, the other electrochemical test strips stored in the container may be affected. For example, when the electrodes in an electrochemical test strip are exposed to air, water vapor, or other environments, the electrode surface is susceptible to oxidation or reduction reactions that reduce its electron transfer capability and/or increase its impedance. This can still cause inaccurate measurements and reduce the lifetime of the electrochemical test strips.

The “prior art” discussion above merely provides a technology background without acknowledging that the “prior art” discussed above reveal the subject matter of this disclosure and do not constitute prior art at this time and that any of the “prior art” discussion above should not be regarded as any part of the present application.

SUMMARY OF THE INVENTION

The present disclosure provides a biochemical test chip, including an electrode unit and a protective layer. The protective layer is electrically connected to the electrode unit. The protective layer is configured to oxidize the electrode unit after the electrode unit receives an electron or reduce the electrode unit after the electrode unit loses an electron. There is a potential difference (Ecell0) between the protective layer and the electrode unit.

In some embodiments, the potential difference (Ecell0) is greater than 0.

In some embodiments, the protective layer is an anode, and the electrode unit is a cathode.

In some embodiments, the protective layer is a cathode, and the electrode unit is an anode.

In some embodiments, the biochemical test chip further includes a first insulating septum, located on the electrode unit, wherein the first insulating septum has a first opening and a second opening, wherein the first opening at least partially exposes the electrode unit, and the second opening at least partially exposes the protective layer.

In some embodiments, the biochemical test chip further includes a second insulating septum, located on the first insulating septum, wherein the second insulating septum has a third opening, and the third opening at least partially exposes the protective layer.

In some embodiments, the electrode unit includes a branch, wherein the branch is configured to provide a conductive platform to the protective layer.

In some embodiments, the electrode unit and the protective layer are substantially located on the same level.

In some embodiments, at least a portion of the electrode unit is made of an active material and is in contact with air.

In some embodiments, the protective layer is configured to protect the portion made of the active material or the whole electrode unit.

The present disclosure provides a biochemical test chip, including a reactive layer, an electrode unit, and a protective layer. The reactive layer is electrically connected to the electrode unit. The protective layer is electrically connected to the electrode unit, and the protective layer is electrically connected to the reactive layer via the electrode unit. The protective layer is configured to oxidize the reactive layer after the reactive layer receives an electron or reduce the reactive layer after the reactive layer loses an electron, wherein there is a potential difference (Ecell0) between the protective layer and the reactive layer.

In some embodiments, the potential difference (Ecell0) is greater than 0.

In some embodiments, the protective layer is an anode, and the reactive layer is a cathode.

In some embodiments, the protective layer is a cathode, and the reactive layer is an anode.

In some embodiments, an oxidation or reduction reaction current level of the reactive layer is greater than an oxidation or reduction reaction current level of the protective layer.

In some embodiments, an oxidation or reduction reaction current level of the reactive layer is greater than or equal to 10-fold an oxidation or reduction reaction current level of the protective layer.

The present disclosure's biochemical test chip is disposed with a protective layer, wherein the protective layer can be used to maintain the stability of the biochemical test chip's reactive layer, so as to protect the biochemical test chip, delay or avoid the unwanted spoilage of the biochemical test chip with the environment, thereby prolonging the shelf-life of the biochemical test chip. Besides, the biochemical test chip can be disposed with a plurality of protective layers to protect different components of the biochemical test chip. For example, the protective layer can further protect the working electrode or the counter electrode and the like so as to decrease the measurement error. Moreover, the biochemical test chip can further include a detachable protective layer so as to accelerate the process for the biochemical test chip to return to the default state.

The foregoing outlines the technical features and advantages of the present disclosure so that those skilled in the art may better understand the following detailed description of the present application. Other technical features and advantages that constitute the subject matter of the present disclosure are described below. Those skilled in the art should appreciate that they may readily use the concepts and specific embodiments provided below as a basis for designing or modifying other structures and processes for carrying out the same purposes and/or achieving the same advantages of the present disclosure. Those skilled in the art should also realize that such equivalent constructions still fall within the present disclosure's spirit and scope as defined in the appended claims.

DETAILED DESCRIPTION

Detailed description of the present disclosure is discussed in detail below. However, it should be understood that the embodiments provide many inventive concepts that can be applied in a variety of specific contexts. The specific embodiments discussed are illustrative of the specific ways they can be made and used and do not limit the present disclosure's scope.

The same reference numeral is configured to represent the same elements/components in the various drawings and illustrative embodiments. Reference will now be made in detail to the illustrative embodiments shown in the drawings. Whenever possible, the same reference numeral is used in the drawings and the specification to represent the same or similar parts. In the drawings, the shape and thickness may be exaggerated for clarity and convenience. The description will be directed specifically to the elements forming part of, or more directly cooperating with, the device disclosed hereunder. As could be appreciated, elements not explicitly shown or described may take various forms. The reference to “some embodiments” or “embodiment” throughout this specification implies that the particular features, structures, or characteristics described in conjunction with the embodiment are included in at least one of the embodiments. Therefore, the phrase “in some embodiments” or “in an embodiment” appearing in various places throughout this specification does not necessarily refer to the same embodiment. Besides, the specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In the drawings, the same reference numeral is configured to indicate the same or similar elements in the various views, and illustrative embodiments of the present application are shown and described. The drawings are not necessarily drawn to scale, and in some cases, the drawings have been exaggerated and/or simplified and are configured for illustrative purposes only. Many possible applications and variations of the present application will be understood by those of ordinary skill in the art in view of the following illustrative embodiments of the present disclosure.

Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meanings as those commonly understood by a person of ordinary skill in the art in the field of the disclosed embodiments. It should be understood, for example, that terms defined in common dictionaries should be construed to have meanings consistent with their meanings in the relevant field and context of this disclosure and should not be construed or understood to have meanings that are too formal unless expressly defined herein.

Besides, the following embodiments are provided to illustrate the core value of this disclosure but are not intended to limit the scope of protection of this disclosure. For clarity and ease of understanding, the same or similar functions or elements among this disclosure's different embodiments are not repeated or shown in the drawings. Besides, different elements or technical features from different embodiments may be combined or substituted to create further embodiments that are still covered by this disclosure, provided they do not conflict with each other.

The present disclosure is directed to an electrochemical system that sacrifices itself to protect a specific object, particularly to a biochemical test chip of the electrochemical system that sacrifices itself to protect a specific object, in particular. Furthermore, the present disclosure is directed to a biochemical test chip, including a protective layer, wherein the protective layer can sacrifice itself to maintain the stability of one or more components in the biochemical test chip. In some embodiments, the protective layer is configured to protect the object in the biochemical test chip that is protected by the protective layer, such as less-stable components in the biochemical test chip or those suspectable to oxidation or reduction. The subject that is protected by the protective layer can be, for example, the electrode unit or reactive layer in the biochemical test chip; however, the present disclosure is not limited thereto. In detail, the present disclosure slows or avoids one or more components in the biochemical test chip to suffer from spoilage other than medical measurements (e.g., unwanted spoilage upon being exposed to the environment) by sacrificing the protective layer (such as by allowing the protective layer to undergo the oxidation or reduction reaction). Depending on the chemical properties of the object to be protected, the protective layer sacrifices itself to undergo the corresponding scarification (e.g., the oxidation or reduction reaction) to facilitate said component(s) to return to the default state or to provide or receive electrons before the component is spoiled, thereby attaining the technical effect of protecting the components.

For example, when it is expected to keep the object to be protected stably in the reduced state, materials capable of providing electrons are chosen to form the protective layer. In other words, when the object to be protected is spoiled because it loses electrons, if the protective layer is made from materials capable of providing or losing electrons, then the protective layer can lose electrons first or compensate for the electrons that the object to be protected loses before the object to be protected loses electrons. In this way, it is feasible to keep the object to be protected stably in the reduced state.

On the other hand, when it is expected to keep the object to be protected stably in the oxidized state, materials capable of receiving electrons are chosen to form the protective layer. In other words, when the object to be protected is spoiled because it receives electrons, if the protective layer is made from materials capable of capturing or accommodating electrons, then the protective layer can obtain electrons first before the object to be protected receives electrons. In this way, it is feasible to keep the object to be protected stably in the oxidized state.

Generally, substances with a higher standard reduction potential tend to receive electrons, whereas substances with a lower standard reduction potential tend to lose electrons. According to the Gibbs Free Energy relationship, i.e., ΔG0=−nFEcell0, where ΔG0is the change in the free energy, n is the mole number of electrons, and F is the charge per mole. The equation for the potential difference (Ecell0) is Ecell0=Ecathode−Eanode, where Ecathodeis the standard reduction potential of a cathode (cathode electrode), and Eanodeis the standard reduction potential of an anode (anode electrode). When the Gibbs free energy ΔG0<0, the reaction is spontaneous. From the above, it can be seen that when two oxidizable/reduceable substances with a potential difference (Ecell0) are in the same reaction tank, the one with higher standard reduction potential will tend to undergo reduction reaction, and the other one will tend to undergo oxidation reaction. For example, when the standard reduction potential of the anode is smaller than that of the cathode, the anode will spontaneously transfer electrons to the cathode, and the cathode will remain in the reduced state because it continues to receive electrons, thus avoiding the influence of environmental oxidants (e.g., oxygen, water vapor, etc.).

Therefore, by disposing the protective layer and the object to be protected in the same reaction tank, and allowing the two to have a potential difference (Ecell0), wherein the potential difference (Ecell0) is greater than 0, it is feasible to allow the protective layer and the object to be protected to generate an electron flow in a specific direction spontaneously so that the object to be protected can be kept in its original redox state. In this way, the biochemical test chip is protected to slow or avoid the unwanted spoilage of the biochemical test chip with the environment.

Depending on the protective layer's materials and the subject to be protected, the protective layer and the object to be protected can respectively be an anode and a cathode, and the protective layer and the object to be protected can also be a cathode and an anode, respectively. The following paragraphs provide several embodiments of the present disclosure, which are used as examples to illustrate the core value of the present disclosure; however, they are not used to limit the protection scope of the present disclosure.

Reference is made toFIG. 1,FIG. 1is a schematic exploded view illustrating a biochemical test chip100according to some embodiments of the present disclosure. The biochemical test chip100can be an electrochemical test chip, which is a device that can be electrically connected to. The biochemical test chip100is configured to collect a specimen and carry out an electrochemical reaction therewith so as to detect a target analyte therein. The specimen includes any liquids or soluble solids having therein one target analyte that can be detected using an electrochemical method. For example, the specimen may include blood, tissue fluid, urine, sweat, tears, and other biological samples; however, the present disclosure is not limited thereto. Moreover, the blood can include the whole blood, plasma, serum, etc.: however, the present disclosure is not limited thereto.

Reference is made toFIG. 1; the biochemical test chip100includes an insulating substrate10, an electrode unit20, a first insulating septum30, a reactive layer40, a second insulating septum50, and the protective layer60. The insulating substrate10includes a substrate that is electrically insulated. In some embodiments, the material of the insulating substrate10can include polyvinyl chloride (PVC), glass fiber (FR-4), polyethersulfone (PES), bakelite, polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyimide (PI), glass plate, ceramic or any combination of the above-mentioned materials; however, the present disclosure is not limited thereto. The material of the insulating substrate10can be adjusted depending on the system or actual needs.

The electrode unit20of the biochemical test chip100is located on the insulating substrate10. The electrode unit20is disposed on the insulating substrate10and configured to be subjected to the electrochemical measurement. The electrochemical measurement includes analyzing the specimen's concentration using an electrical reaction, such as potentiometry, conductometry, voltammetry, polarimetry, high-frequency titration, amperometry, Coulombic method, electrolysis, and the like. The electrode unit20includes a working electrode22and a counter electrode24; however, the present disclosure is not limited thereto. The electrode unit20can have other electrodes depending on the requirements of the system. The working electrode22is the electrode that allows the conductive medium to undergo the electrooxidation reaction or electroreduction reaction on the surface thereof and can be used by the measuring apparatus to determine the concentration. In detail, the electrooxidation reaction or electroreduction reaction is an electrochemical reaction in which the conductive medium undergoes an exchange between electrical and chemical energy on the surface of the working electrode22.

The polarity of the working electrode22can be an anode or a cathode, depending on the requirement of the measurement reaction. For example, if the conductive medium is oxidized on the working electrode22, the working electrode22is an anode; if the conductive medium is reduced on the working electrode22, the working electrode22is a cathode. The counter electrode24is an electrode that undergoes the electroreduction reaction or electrooxidation reaction corresponding to the working electrode22so that the overall electrochemical system satisfies the principles of charge balance. The potential and polarity of the counter electrode24are opposite to the potential and the polarity of the working electrode22. Before being in contact with the specimen, the working electrode22and the counter electrode24are insulated from each other. After the working electrode22and the counter electrode24are in contact with the specimen, they form an electrical loop with the measuring apparatus. In some embodiments, the working electrode22and the counter electrode24can include a carbon electrode, silver electrode, platinum electrode, etc.; however, the present disclosure is not limited thereto.

The materials of the working electrode22and the counter electrode24can vary depending on the system's requirement.

The first insulating septum30is disposed on the insulating substrate10and located on the electrode unit20. The first insulating septum30can have an opening32, wherein the opening32at least partially exposes the electrode unit20. In some embodiments, the opening32is located at the front side30F of the first insulating septum30and exposes a portion of the electrode unit20. The opening32is configured to define a reaction zone34in the biochemical test chip100; the reaction zone34is configured to accommodate the specimen. The electrode unit20is exposed from the portion of the opening32and can undergo the electrochemical reaction with the specimen. The size or shape of the opening32can be adjusted according to the desired area of the electrode unit20and the desired volume of the specimen. In some embodiments, the backside30B of the first insulating septum30exposes a portion of the electrode unit20to form a connecting zone10C. The electrode unit20exposed from the connecting zone10C can be electrically connected to a measuring apparatus (not shown in the drawings). The measuring apparatus and the biochemical test chip100are electrically connected to provide the energy required for the electrochemical measurement and analyze the reaction signal. In some embodiments, the material of the first insulating septum30includes a PVC insulation tape, PET insulation tape, heat drying insulation paint, or ultraviolet (UV) curable insulation paint; however, the present disclosure is not limited thereto.

FIG. 2is a partial top view illustrating the biochemical test chip100according to some embodiments of the present disclosure. Reference is made toFIG. 2andFIG. 1simultaneously; the biochemical test chip100further includes a reactive layer40. The reactive layer40is located in the opening32of the first insulating septum30. The reactive layer40is 1 electrically connected to the electrode unit20. In some embodiments, the area of the reactive layer40is smaller than the size of the opening32. The reactive layer40at least partially covers the electrode unit20exposed from the opening32. In some embodiments, the reactive layer40covers both the working electrode22and the counter electrode24. In some embodiments, the reactive layer40only covers the working electrode22. The reactive layer40is configured to undergo a chemical reaction with the specimen. In other embodiments, the biochemical test chip100does not include the reactive layer40.

In some embodiments, the reactive layer40includes an enzyme and a conductive medium. For example, the enzyme includes a fixed or non-fixed enzyme, such as redox enzymes, antigens, antibodies, microbial cells, animal and plant cells, and biologically identifiable components of animal and plant tissues. The conductive medium is configured to receive electrons generated after the reaction between the enzyme and a blood specimen and transmit the electrons to the measuring apparatus via the electrode unit20. In some embodiments, the conductive medium can include potassium hexacyanoferrate(III), potassium hexacyanoferrate(II) trihydrate, ruthenium complex, ferrocene, sodium dithionite, nicotinamide adenine dinucleotide (NAD+), nicotinamide adenine dinucleotide phosphate (NADP+), thiamin pyrophosphate (TPP), coenzyme A (HSCoA), flavin adenine dinucleotide (FAD) or a combination thereof; however, the present disclosure is not limited thereto. In some embodiments, the reactive layer40can be further supplemented with a phosphate buffer and protectants, such as a protein, dextrin, glucan, amino acid, etc.; however, the present disclosure is not limited thereto.

Reference is made again toFIG. 1; the second insulating septum50is located on the first insulating septum30. In some embodiments, the second insulating septum50at least partially covers the opening32of the first insulating septum30so that the opening32forms a capillary structure. In some embodiments, the terminus of the second insulating septum50is disposed with a vent502corresponding to the opening32. The vent52can be of any shape; for example, the vent52can be circular, oval, rectangular, rhombus, etc. In some embodiments, the second insulating septum50also exposes the connecting zone10C of the electrode unit20. The second insulating septum50can be of any shape or size.

Reference is made toFIG. 2andFIG. 1simultaneously; the biochemical test chip100further includes the protective layer60. For example, water vapor or oxygen and the like in the environment may exist between the insulating substrate10and the first insulating septum30. Therefore, the reactive layer40exposed to the environment and the electrode unit20disposed between the insulating substrate10and the first insulating septum30may get spoiled upon being oxidized with the water vapor or oxygen in the air.

In the present embodiment, the protective layer60can be configured to protect the reactive layer40in the biochemical test chip100to slow or avoid the unwanted spoilage of the biochemical test chip100in the environment.

In some embodiments, as shown inFIG. 1, the first insulating septum30can have an opening34, and the second insulating septum50can have an opening54, wherein the opening34and the opening54at least partially expose the protective layer60. The protective layer60and the reactive layer40can be exposed to the same environment; however, the present disclosure is not limited thereto. For example, the protective layer60can be disposed between the insulating substrate10and the first insulating septum30and is exposed to the same environment as the reactive layer40via the opening34and the opening54. In other embodiments, the protective layer60can and the reactive layer40are exposed to different environments. For example, the protective layer60can be disposed between the insulating substrate10and the first insulating septum30, and the first insulating septum30and the second insulating septum50do not have the opening34and opening54.

The protective layer60is disposed at a specific region of the electrode unit20. For example, the protective layer60is disposed on the working electrode22; however, the present disclosure is not limited thereto. As shown inFIG. 1, the protective layer60is disposed on the electrode unit20and is electrically connected to the electrode unit20. The protective layer60and the reactive layer40are electrically coupled via the electrode unit20. In the present embodiment, the protective layer60is electrically connected to the reactive layer40via the working electrode22; however, the present disclosure is not limited thereto. In other embodiments, the protective layer60can be electrically connected to the reactive layer40via the counter electrode24. The position of the protective layer60is not limited to those described above; in some embodiments, the protective layer60can be disposed on the second insulating septum50and electrically connected to the electrode unit20via wires. In other embodiments, the protective layer60can be disposed between the first insulating septum30and the second insulating septum50and electrically connected to the electrode unit20via wires.

In the present embodiment, the protective layer60is configured to protect the reactive layer40in the biochemical test chip100. The protective layer60and the reactive layer40can have different materials or compositions. For example, the protective layer60and the reactive layer40can have different standard reduction potential s, and hence, there is a potential difference (Ecell0) between the protective layer60and the reactive layer40. The potential difference (Ecell0) between the protective layer60and the reactive layer40is greater than 0. The protective layer60and the reactive layer40are in the same reaction environment. In some embodiments, the protective layer60and the reactive layer40are in contact with air simultaneously; however, the present disclosure is not limited thereto. The protective layer60and the reactive layer40electrically connected to the electrode unit20simultaneously can also be considered the two being in the same reaction environment. Because there is a potential difference (Ecell0) between the protective layer60and the reactive layer40, and the potential difference (Ecell0) is greater than 0, an electron flow in a specific direction is generated spontaneously so that the object to be protected (the reactive layer40) can be kept in its original redox state. In this way, the biochemical test chip100is protected to slow or avoid the unwanted spoilage of the biochemical test chip100with the environment.

Depending on the materials of the protective layer60and the reactive layer40, the protective layer60and the reactive layer40can respectively be an anode and a cathode, and the protective layer60and the reactive layer40can also be a cathode and an anode, respectively. In the following paragraphs,FIG. 3andFIG. 4are respectively used to discuss the examples where the protective layer60is the cathode and the reactive layer40is the anode, and the protective layer60is the anode and the reactive layer40is the cathode. In some embodiments, the area of the protective layer60is greater than the area of the reactive layer40. In some embodiments, the area of the protective layer60is substantially the same as the area of the reactive layer40. The area and the thickness of the protective layer60and the reactive layer40can be adjusted depending on the system requirements.

Reference is made toFIG. 3;FIG. 3is a schematic cross-sectional view taken from the line A-A′ inFIG. 2. In the present embodiment, the conductive medium of the reactive layer40can be ferricyanide (hexacyanoferrate(III)); however, ferricyanide tends to be reduced into ferrocyanide (hexacyanoferrate(II)) upon light irradiation, wherein the reaction equation can be expressed as FeIII(CN)63−→hvFeII(CN)64−. When ferricyanide is reduced into ferrocyanide conductive medium, this spoilage results in the increases of the background current when the biochemical test chip100performs the concentration measurement, thereby causing measurement errors.

As shown inFIG. 2andFIG. 3, the biochemical test chip100of the present disclosure is disposed with the protective layer60, wherein the protective layer60is electrically connected to the reactive layer40via the electrode unit20. Thus, when the biochemical test chip100is exposed to the environment and before the specimen is loaded, the reactive layer40, the electrode unit20, the protective layer60, and the air form a chemical reaction tank. In the present embodiment, the material of the protective layer60can be silver oxide (silver peroxide). Silver oxide can undergo the reduction reaction and give silver, wherein the reaction equation can be expressed as Ag2O+2H++2e−→2Ag+H2O. The standard reduction potential of silver oxide/silver is about 1.77 V, and the standard reduction potential of ferricyanide/ferrocyanide is about 0.36 V. Therefore, in the present embodiment, the protective layer60is the cathode, whereas the reactive layer40is the anode. The potential difference (Ecell0) between the protective layer60and the reactive layer40is 1.41 V. Since the potential difference between the two is greater than 0, the change in free energy is smaller than 0, and thus, ferrocyanide in the reactive layer40undergoes spontaneous oxidation reaction into ferricyanide, wherein the reaction equation can be expressed as 2Fe(CN)6+Ag2O+2H+→2Fe(CN)63−+2Ag+H2O. In this case, the half-reaction taking place on the reactive layer40is FeII(CN)64−→FeIII(CN)63−+e−.

In view of the above, ferrocyanide in the reactive layer40is oxidized into ferricyanide because of the reduction reaction of silver oxide in the protective layer60. When the reduction reaction of the protective layer60takes place, the reactive layer40undergoes the oxidation reaction, thereby mitigating the reduction reaction due to the light irradiation. Therefore, by disposing the protective layer60in the biochemical test chip100, it is feasible to effectively avoid the conductive medium in the reactive layer40from being spoiled before measuring the specimen. The composition materials of the conductive medium of the reactive layer40and the protective layer60are not limited to those discussed above. In some embodiments, the composition materials of the conductive medium of the reactive layer40and the protective layer60are selected so that the potential difference (Ecell0) between the two is greater than 0.

In the present embodiment, a method for protecting the biochemical test chip100is provided. In detail, the present method for protecting the biochemical test chip100includes providing the protective layer60electrically connected to the electrode unit20, wherein the protective layer60is electrically connected to the reactive layer40via the electrode unit20. The protective layer60is configured to oxidize the reactive layer40after the reactive layer40receives electrons. As discussed above, ferricyanide in the reactive layer40tends to receive electrons and thus is reduced into ferrocyanide upon light irradiation. Hence, one may choose a material with a standard reduction potential greater than the standard reduction potential of ferricyanide/ferrocyanide as the protective layer60; for example, one may choose silver oxide as the protective layer60. Therefore, after the reactive layer40receives electrons, the protective layer60allows the reactive layer40to undergo the oxidation reaction so that the reactive layer40returns to the default state. In the present embodiment, the standard reduction potential of the reactive layer40is smaller than the standard reduction potential of the protective layer60; however, the present disclosure is not limited thereto.

Reference is made toFIG. 4;FIG. 4is a schematic cross-sectional view taken from the line A-A′ inFIG. 2. In the present embodiment, the standard reduction potential of the reactive layer40is greater than the standard reduction potential of the protective layer60. In the present embodiment, the conductive medium of the reactive layer40can be ferrocyanide; however, ferrocyanide, when being exposed to the air, tends to be oxidized by oxygen into ferricyanide, wherein the reaction equation can be expressed as FeII(CN)64−+O2+2H+→2FeIII(CN)63−+H2O2. When ferrocyanide is oxidized into ferricyanide after it is in contact with oxygen, this spoilage results in the change of the conductive medium's concentration in the biochemical test chip100, thereby affecting the background current and causing measurement errors.

As shown inFIG. 2andFIG. 4, the biochemical test chip100of the present disclosure is disposed with the protective layer60, wherein the protective layer60is electrically connected to the reactive layer40via the electrode unit20. Thus, when the biochemical test chip100is exposed to the environment and before the specimen is loaded, the reactive layer40, the electrode unit20, the protective layer60, and air form a chemical reaction tank. In the present embodiment, the material of the protective layer60can be iron. When being exposed to the air, iron tends to undergo oxidation reaction with water vapor, wherein the half-reaction equation can be expressed as Fe+2OH−→Fe(OH)2+2e−. The standard reduction potential of ferricyanide/ferrocyanide is about 0.36 V, whereas the standard reduction potential of iron(II) hydroxide/iron is about −0.89 V. Thus, in the present embodiment, the reactive layer40is the cathode, and the protective layer60is the anode. When the biochemical test chip100is exposed to the environment having water vapor and oxygen, the potential difference (Ecell0) between the protective layer60and the reactive layer40is 1.25 V. Since the potential difference between the two is greater than 0, the change in free energy is smaller than 0; and hence, ferricyanide in the reactive layer40undergoes the spontaneous reduction reaction into ferrocyanide, wherein the reaction equation can be expressed as 2FeIII(CN)63−+Fe+2OH−→2FeII(CN)64−+Fe(OH)2. In this case, the half-reaction on the reactive layer40can be expressed as FeIII(CN)63−+e−→FeII(CN)64−.

Hence, ferricyanide in the reactive layer40is reduced into ferrocyanide because of iron's oxidation reaction in the protective layer60. When the oxidation reaction of the protective layer60takes place, the reactive layer40undergoes the reduction reaction, thereby slowing the oxidation reaction due to oxygen in the air. Besides, the reactive layer40is protected by the oxidation of the water vapor in the air to iron so as to keep the desired stability of the conductive medium of the reactive layer40. Therefore, by disposing the protective layer60in the biochemical test chip100, it is feasible to effectively avoid the conductive medium in the reactive layer40from being spoiled before measuring the specimen. The composition materials of the conductive medium of the reactive layer40and the protective layer60are not limited to those discussed above.

In the present embodiment, a method for protecting the biochemical test chip100is provided. In detail, the present method for protecting the biochemical test chip100includes providing the protective layer60electrically connected to the electrode unit20, wherein the protective layer60is electrically connected to the reactive layer40via the electrode unit20. The protective layer60is configured to reduce the reactive layer40after the reactive layer40loses electrons. As discussed above, ferrocyanide in the reactive layer40tends to be oxidized into ferricyanide by oxygen when being exposed to the air. Hence, one may choose a material with a standard reduction potential smaller than the standard reduction potential of ferricyanide/ferrocyanide as the protective layer60; for example, one may choose iron as the protective layer60. Therefore, after the reactive layer40loses electrons, the protective layer60allows the reactive layer40to undergo the reduction reaction so that the reactive layer40returns to the default state. In the present embodiment, the standard reduction potential of the reactive layer40is greater than the standard reduction potential of the protective layer60; however, the present disclosure is not limited thereto.

The foregoing are examples of the protective layer60and the reactive layer40, and the present disclosure is not limited thereto. By choosing appropriate materials as the protective layer60, it is feasible that the potential difference (Ecell0) between the protective layer60and the reactive layer40is greater than 0. In this way, the protective layer60and the reactive layer40are under spontaneous reactions so as to protect the biochemical test chip100and prolong the shelf-life of the biochemical test chip100.

The material of the protective layer60can be determined based on the material of the reactive layer40. For example, when it is desired to stabilize the conductive medium of the reactive layer40in the oxidized state, materials suitable for use as a cathode are chosen as the material of the protective layer60, i.e., materials capable of receiving electrons can be used. In other words, when the reactive layer40spoils upon receiving electrons, materials capable of capturing or accommodating electrons are chosen as the material of the protective layer60; hence, the protective layer60receives electrons first before the reactive layer40receives electrons. In this way, the reactive layer40is stabilized in the oxidized state. Generally, substances with a higher standard reduction potential tend to receive electrons, whereas substances with a lower standard reduction potential end to lose electrons. When it is expected to keep the reactive layer40stably in the oxidized state, materials with a standard reduction potential greater than that of the reactive layer40are chosen to form the protective layer60.

When it is expected to keep the reactive layer40stably in the reduced state, materials suitable for use as an anode are chosen as the material of the protective layer60; i.e., materials capable of providing electrons can be used. In other words, when the reactive layer40is spoiled because it loses electrons, if the protective layer60is made from materials capable of providing or losing electrons, then the protective layer60can lose electrons first or compensate for the electrons that the reactive layer40loses before the reactive layer40loses electrons. In this way, it is feasible to keep the reactive layer40stably in a reduced state. As discussed above, when it is expected to keep the reactive layer40stably in the reduced state, materials with a standard reduction potential lower than that of the reactive layer40are chosen to form the protective layer60.

Generally, in addition to the reactive layer40, components in the biochemical test chip100that are susceptible to redox reaction further include the working electrode22and the counter electrode24. In some embodiments, the biochemical test chip100can be disposed with an additional protective layer to protect the working electrode22or the counter electrode24. In some embodiments, the protective layer60can protect the working electrode22and the reactive layer40simultaneously. In some embodiments, the protective layer60must be in physical contact with the object to be protected to provide the protection. The subject to be protected can include the reactive layer40, the working electrode22, the counter electrode24, or other units in the biochemical test chip100. In other embodiments, the protective layer60can protect the protection by merely being electrically coupled to the object to be protected. In some embodiments, when the protective layer60is in contact with an object to be protected that is made of compounding materials, one should avoid the counterreaction on the parts other than the object to be protected. Hence, the protective layer60is designed to be in electrical contact only with the object to be protected.

It should be noted that in order to prevent the protective layer60from interfering with the biochemical test chip100during the electrochemical measurement, the protective layer60according to the present disclosure is disconnected during the concentration measurement reaction. In some embodiments, as shown inFIG. 2, the protective layer60is connected in series with the reactive layer40via the working electrode22and the branch22A thereof. In some embodiments, the protective layer60can be connected to the multiple branches of the working electrode22so as to form a parallel connection with the reactive layer40. In some embodiments, the biochemical test chip100may be connected to a circuitry switch that disconnects the protective layer60through the circuitry switch while the biochemical test chip100is under the electrochemical measurement. When the biochemical test chip100is electrically connected to the measuring instrument, the protective layer60is electrically separated from the electrode unit20. Besides, the biochemical test chip100is electrochemically measured by providing a reaction potential through an external meter to drive the concentration measurement reaction. The order of magnitude of the chemical reactions in the reaction layer40will be much higher than the oxidation or reduction chemical reactions between the protective layer60and the reaction layer40. Thus, the protective layer60will not affect the concentration measurement reaction of the biochemical test chip100. In some embodiments, the oxidation or reduction reaction current level of the reaction layer40is greater than or equal to 10 times (inclusive) the oxidation or reduction reaction current level of the protective layer60. In some embodiments, the oxidation or reduction reaction current level of the reaction layer40is greater than or equal to 50 times (inclusive) the oxidation or reduction reaction current level of the protective layer60. In some embodiments, the oxidation or reduction reaction current level of the reaction layer40is greater than or equal to 100 times (inclusive) the oxidation or reduction reaction current level of the protective layer60. For example, to ensure that the oxidation or reduction reaction of the protective layer60does not interfere with the measurement reaction (i.e., the reaction of the reaction layer40), if the minimum oxidation or reduction reaction current level of the reaction layer40(i.e., the lowest concentration oxidation or reduction reaction current level on the system specification) is 1 microampere (μA), the oxidation or reduction reaction current level of the protective layer60should be less than 0.01 μA. Thus, the oxidation or reduction reaction current level of the reaction layer40is preferably greater than or equal to more than 100 times (inclusive) the oxidation or reduction reaction current level of the protective layer60. In some embodiments, the role of the protective layer60relatives to the reaction layer40may also change so that the protective layer60does not affect the results of the concentration measurement reaction.

In some embodiments, the branch22A of the working electrode22is provided to provide the protective layer60a conductive platform. In some embodiments, the working electrode22and the branch22A thereof may have the same or different materials. In some embodiments, the branch22A of the working electrode22may include carbon, such as a carbon layer. In other embodiments, the working electrode22may not have a branch22A, and the protective layer60may be provided directly on the working electrode22.

The present disclosure is not limited to the foregoing embodiments and can comprise other different embodiments. For simplification purposes and to facilitate the comparison among embodiments of the present disclosure, in the following embodiments, each of the completely the same elements is labeled with completely the same reference numeral. To further facilitate the comparison among the differences between these embodiments, only the differences among different embodiments are discussed, whereas the completely the same features are not discussed for the sake of brevity.

In some embodiments, the protective layer60can configured to protect the electrode unit20. Reference is made toFIG. 5;FIG. 5is a schematic exploded view illustrating a biochemical test chip200according to some embodiments of the present disclosure. As shown inFIG. 5, the difference between the biochemical test chip200and the biochemical test chip100is that the electrode unit20and the protective layer60locate at substantially the same level. In some embodiments, only a portion of the electrode unit20is disposed on the protective layer60. For example, the electrode unit20includes a branch, wherein the branch is disposed on the protective layer60. The branch can be the branch22A of the working electrode22, the branch24A of the counter electrode24(shown inFIG. 8), or the branch of a reference electrode. In some embodiments, the branch can be configured to provide the protective layer60a conductive platform.

In the present embodiment, the working electrode22of the electrode unit20is disposed on the protective layer60, and the counter electrode22of the electrode unit20and the protective layer60are disposed on the same level; however, the present disclosure is not limited thereto. In some embodiments, only the branch22A of the working electrode22in the electrode unit20is disposed on the protective layer60. For example, the working electrode22and the protective layer60locate at substantially the same level; only the branch22A of the working electrode22is disposed on the protective layer60. In the present embodiment, the first insulating septum30and the second insulating septum50do not have the opening34and the opening54; however, the present disclosure is not limited thereto. In other embodiments, openings may be disposed on the first insulating septum30and the second insulating septum50depending on the system requirements. For example, the first insulating septum30can have the opening34, and the second insulating septum50can have the opening54, wherein the opening34and the opening54at least partially expose the branch22A of the working electrode22.

In some embodiments, the electrode unit20completely covers the protective layer60, and the reactive layer40is disposed on the electrode unit20. In detail, the working electrode22of the electrode unit20completely covers the protective layer60. In some embodiments, the branch22A of the working electrode22can completely cover the protective layer60. In some embodiments, the area of the branch22A of the working electrode22is greater than the area of the protective layer60. In some embodiments, the thickness of the working electrode22is greater than the thickness of the protective layer60. In some embodiments, the thickness of the working electrode22is substantially the same as the thickness of the protective layer60.

As shown inFIG. 5, the biochemical test chip200is disposed with the protective layer60, and the protective layer60is electrically connected to the electrode unit20. In some embodiments, the protective layer60is configured to protect the electrode unit20. In some embodiments, the protective layer60is configured to protect part of or the whole electrode unit20. In some embodiments, the protective layer60is configured to protect the portion of the electrode unit20that is made of the active material or the whole electrode unit. The active material can include a conductive material, such as silver or other suitable metal materials. In the present embodiment, the protective layer60is configured to protect the working electrode22of the electrode unit20. For example, the material of the working electrode22can include silver; however, silver tends to react with oxygen and water vapor in the air and get oxidized into silver oxide, wherein the reaction equation can be expressed as 4Ag+O2→2Ag2O. When silver is oxidized into silver oxide after being exposed to the air, it will result in the toxification on the surface of the working electrode22; thereby reducing the working electrode22's conductivity and its capability to receive electrons; such spoilage will result in measurement errors when the biochemical test chip200is subject to the concentration measurement.

The biochemical test chip200according to the present disclosure is disposed with the protective layer60, wherein the protective layer60is electrically connected to the electrode unit20. Thus, when the biochemical test chip200is exposed to the environment and before the specimen is loaded, the electrode unit20, the protective layer60, and air form a chemical reaction tank. In the present embodiment, the material of the protective layer60can include ferrocene, wherein the ferric iron located at the center of ferrocene is susceptible to valence transition and undergoes the redox reaction, wherein the reaction equation can be expressed as FeII(C5H5)2→FeIII(C5H5)2+e−, and the standard reduction potential thereof is about 0.16 V. The standard reduction potential of silver oxide/silver is about 1.17 V. The standard reduction potential of ferrocene is smaller than the standard reduction potential of silver oxide/silver. Thus, in the present embodiment, the protective layer60is the anode, whereas the electrode unit20is the cathode. The potential difference (Ecell0) between the protective layer60and the electrode unit20is about 1.01 V. Since the potential difference between the two is greater than 0, the change in free energy is smaller than 0, and hence, silver oxide in the electrode unit20undergoes the spontaneous reduction reaction into silver, wherein the reaction equation can be expressed as 2FeII(C5H5)2+Ag2O+2H+→2FeIII(C5H5)2+2Ag+H2O.

In view of the above, silver oxide in the working electrode22is reduced to silver because of ferrocene's oxidation reaction in the protective layer60. When the protective layer60is oxidized, the working electrode22of the electrode unit20undergoes the reduction reaction, thereby slowing the oxidation reaction of oxygen and water vapor in the air. Therefore, by disposing the protective layer60in the biochemical test chip200, one can effectively prevent the electrode unit20from spoilage before measuring the specimen. The composition materials of the electrode unit20and the protective layer60are not limited thereto.

The material of the protective layer60is not limited to ferrocene. In some embodiments, the material of the protective layer60can include a metallocene or a macrocycle; however, the present disclosure is not limited thereto. For example, the metallocene can include vanadocene, chromocene, manganocene, ferrocene, cobaltocene, nickelocene, rhodocene, etc. The macrocycle can include iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, copper phthalocyanine, etc.

In the present embodiment, a method for protecting the biochemical test chip200is provided. In detail, the present method for protecting the biochemical test chip200includes providing the protective layer60electrically connected to the electrode unit20. The protective layer60is configured to reduce the electrode unit20after the electrode unit20loses electrons. As discussed above, silver in the electrode unit20tends to be oxidized into silver oxide by oxygen when being exposed to the air. Hence, one may choose a material with a standard reduction potential smaller than the standard reduction potential of silver/silver oxide as the protective layer60; for example, one may choose ferrocene as the protective layer60. Therefore, after the electrode unit20loses electrons, the protective layer60allows the electrode unit20to undergo the reduction reaction so that the electrode unit20returns to the default state. In the present embodiment, the standard reduction potential of the electrode unit20is greater than the standard reduction potential of the protective layer60; however, the present disclosure is not limited thereto.

In other embodiments, the standard reduction potential of the electrode unit20is smaller than the standard reduction potential of the protective layer60. For example, the present disclosure further provides a method for protecting the biochemical test chip200, including providing the protective layer60that is electrically connected to the electrode unit20. The protective layer60is configured to oxidize the electrode unit20after the electrode unit20receives electrons. As discussed above, one can choose a material with a standard reduction potential greater than the standard reduction potential of the electrode unit20as the protective layer60. Therefore, after the electrode unit20receives electrons, the protective layer60allows the electrode unit20to undergo the oxidation reaction so that the electrode unit20returns to the default state.

The foregoing is only an example of the protective layer60and the electrode unit20, and the present disclosure is not limited thereto. By choosing appropriate materials as the protective layer60, the potential difference (Ecell0) between the protective layer60and the electrode unit20can be greater than 0. In this way, the protective layer60and the electrode unit20are in spontaneous reactions, thereby protecting the biochemical test chip200and prolonging the shelf-life of the biochemical test chip200.

Reference is made toFIG. 6;FIG. 6is a schematic exploded view illustrating a biochemical test chip300according to some embodiments of the present disclosure. As shown inFIG. 6, the difference between the biochemical test chip300and the biochemical test chip100is that the electrode unit20of the biochemical test chip300does not include the branch22A. In some embodiments, the protective layer60can be directly disposed on the working electrode22of the electrode unit20; however, the present disclosure is not limited thereto. In other embodiments, the protective layer60can be directly disposed on the counter electrode24of the electrode unit20.

Reference is made toFIG. 7;FIG. 7is a schematic exploded view illustrating a biochemical test chip400according to some embodiments of the present disclosure. As shown inFIG. 7, the difference between the biochemical test chip400and the biochemical test chip100is that the biochemical test chip400includes a detachable protective layer70, instead of the protective layer60. Generally, during the production or manufacturing process of the biochemical test chip400, components in the biochemical test chip400may be spoiled due to the manufacturing environment. For example, the reactive layer40is in the liquid form before being dried, and the electrode unit20is subject to a high-temperature electrode manufacturing process; this unavoidable environment of high temperature, high humidity, and light irradiation will result in the spoilage of the biochemical test chip400, thereby leading to measurement errors. Thus, in some embodiments, the biochemical test chip400further includes the detachable protective layer70. When the biochemical test chip400is at rest, the detachable protective layer70can be used to restore the spoiled unit to the default state. It is worth noting that the detachable protective layer70of the present embodiment refers to a protective layer that is not disposed in the biochemical test chip400, and the detachable protective layer70is replaceable and can be removed before being connected with a measuring apparatus subjected to measurement reaction. In some embodiments, an external force (e.g., applying a voltage) can be applied on the detachable protective layer70to accelerate the restoration of the biochemical test chip400.

In some embodiments, the detachable protective layer70is electrically connected to the electrode unit20so as to restore the biochemical test chip400to the default state. As shown inFIG. 7, the detachable protective layer70is covered on the electrode unit20via the insulation tape72. After the biochemical test chip400returns to the default state, the detachable protective layer70can electrically isolate the electrode unit20. For example, the detachable protective layer70can be removed by stripping off the insulation tape72. In some embodiments, the detachable protective layer70is electrically connected to the reactive layer40. In some embodiments, the detachable protective layer70is connected to the counter electrode24.

Reference is made toFIG. 8;FIG. 8is a partial top view illustrating a biochemical test chip500according to some embodiments of the present disclosure. As shown inFIG. 8, the difference between the biochemical test chip500and the biochemical test chip100is that the protective layer60of the biochemical test chip500is disposed on one side of the counter electrode24. In the present embodiment, the protective layer60is electrically connected to the counter electrode24. The protective layer60is configured to protect the counter electrode24. In some embodiments, the protective layer60can be disposed on the counter electrode24. For example, the protective layer60can be disposed on the branch24A of the counter electrode24. In some embodiments, the protective layer60can also be disposed under the counter electrode24. The relative positions of the protective layer60and the electrode unit20can be adjusted depending on the system requirements.

Reference is made toFIG. 9;FIG. 9is a partial top view illustrating a biochemical test chip600according to some embodiments of the present disclosure. As shown inFIG. 9, the difference between the biochemical test chip600and the biochemical test chip100is that the biochemical test chip600can include multiple protective layers60,62, such as the protective layer60and the protective layer62. The protective layer60is electrically connected to the working electrode22, whereas the protective layer62is electrically connected to the counter electrode24. The protective layer60is configured to protect the working electrode22or the reactive layer40, whereas the protective layer62configured to protect the counter electrode24. In the present embodiment, the reactive layer40is only in contact with the working electrode22but is not in contact with the counter electrode24. Therefore, the protective layer60is electrically connected to the reactive layer40via the working electrode22.

The biochemical test chip600can protect different regions in the biochemical test chip600by disposing multiple protective layers. For example, the protective layer60is configured to protect the stability of the reactive layer40, whereas the protective layer62is configured to protect the counter electrode's stability24. In other embodiments, the protective layer60is configured to protect the stability of the working electrode22, whereas the protective layer62is configured to protect the stability of the counter electrode24. The protective layer60and the protective layer62can have the same or different materials. Moreover, the protective layer60and the protective layer62can have different areas; however, the present disclosure is not limited thereto. In some embodiments, the area of the protective layer60is greater than the area of the protective layer62. In some embodiments, the protective layer60and the protective layer62locate at a different level; however, the present disclosure is not limited thereto. For example, the protective layer60can locate on the working electrode22, whereas the protective layer62can locate under the counter electrode24.

FIG. 10AandFIG. 10Bprovide test results from samples with five different blood glucose concentrations to illustrate the difference between the present disclosure and conventional techniques. In detail,FIG. 10AandFIG. 10Bshow the signal regression analysis of five replicate experiments of five blood glucose specimens (100 mg/dL, 200 mg/dL, 300 mg/dL, 400 mg/dL, and 500 mg/dL) measured by biochemical test chip with accelerated aging at 50° C. for four weeks and a biochemical analyzer.FIG. 10Ashows the signal of the biochemical specimen without the protective layer, andFIG. 10Bshows the signal of the biochemical specimen with the protective layer. The solid lines inFIG. 10AandFIG. 10Bare standard values.

As shown inFIG. 10A, when the blood glucose concentration is 100 mg/dL, the signal expression of biochemical test chip without the protective layer is relatively high. Moreover, when the blood glucose concentration is greater than 300 mg/dL (inclusive), the signals of the biochemical test chip without the protective layer are all lower than the biochemical analyzer and all exceed the acceptable range of ±10%. As shown inFIG. 10B, when the blood glucose concentration is lower than 300 mg/dL (inclusive), the signals obtained by the biochemical test chip according to the present disclosure are relatively concentrated and are similar to the biochemical analyzer results. Moreover, at all the blood glucose, the signals obtained by the biochemical test chip according to the present disclosure are all within the acceptable range.

The foregoing discussion of the present disclosure provides a biochemical test chip disposed with a protective layer, wherein the protective layer can be used to maintain the stability of the biochemical test chip's reactive layer so as to protect the biochemical test chip, delay or avoid the unwanted spoilage of the biochemical test chip with the environment, thereby prolonging the shelf-life of the biochemical test chip. Besides, the biochemical test chip can be disposed with a plurality of protective layers to protect different components of the biochemical test chip. For example, the protective layer can further protect the working electrode or the counter electrode and the like so as to decrease the measurement error. Moreover, the biochemical test chip can further include a detachable protective layer so as to accelerate the process for the biochemical test chip to return to the default state.

Although the disclosure and its advantages have been described in detail, it should be understood that various modifications, substitutions, and replacements can be made without departing from the spirit and scope of the present disclosure as defined by the appended claims. Besides, the scope of the present application is not limited to specific examples of processes, machines, manufactures, material components, means, methods, and procedures described in the specification. Those skilled in the art can understand from the disclosure of the present application that existing or future developed processes, machinery, manufacturing, and materials that have the same functions or achieve substantially the same results as the corresponding embodiments described herein can be used according to this disclosure. Accordingly, such process, machine, manufacture, material composition, means, method, or step fall within the protection scope of the present application.