CN113884553A - Oxygen sensor and method for measuring oxygen concentration to be measured - Google Patents
Oxygen sensor and method for measuring oxygen concentration to be measured Download PDFInfo
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- CN113884553A CN113884553A CN202111134073.6A CN202111134073A CN113884553A CN 113884553 A CN113884553 A CN 113884553A CN 202111134073 A CN202111134073 A CN 202111134073A CN 113884553 A CN113884553 A CN 113884553A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/4162—Systems investigating the composition of gases, by the influence exerted on ionic conductivity in a liquid
Abstract
Embodiments of the present disclosure provide an oxygen sensor and a method of measuring a concentration of oxygen to be measured. The oxygen sensor comprises a substrate, a first electrode, a dielectric layer and a conductive probe, wherein the first electrode is arranged on the substrate; the dielectric layer is arranged on one side of the first electrode, which is far away from the substrate; the first electrode and the conductive probe are configured to apply a driving voltage to the dielectric layer to drive the dielectric layer to produce an oxygen vacancy conducting filament. The oxygen sensor has the advantages of simple structure, easy preparation, small integral size, repeated use, long service life, accurate detection result and the like.
Description
Technical Field
Embodiments of the present disclosure relate to an oxygen sensor and a method of measuring a concentration of oxygen to be measured using the same.
Background
The oxygen sensor is a sensor for measuring oxygen concentration, and generally uses an oxygen sensitive ceramic element to measure oxygen potential, calculate corresponding oxygen concentration according to a chemical equilibrium principle, and convert the corresponding oxygen concentration into a corresponding electric signal to be output. The oxygen sensor is widely applied to industries such as automobiles, petrochemical industry, fire fighting, medical institutions, gas emission monitoring and the like.
Disclosure of Invention
Embodiments of the present disclosure provide a novel oxygen sensor that achieves the purpose of measuring oxygen concentration using a material capable of generating oxygen vacancy conductive filaments under electric drive as an oxygen sensing element, unlike a conventional oxygen sensor using a ceramic sensing element.
At least one embodiment of the present disclosure provides an oxygen sensor. The oxygen sensor comprises a substrate, a first electrode, a dielectric layer and a conductive probe, wherein the first electrode is arranged on the substrate; the dielectric layer is arranged on one side of the first electrode, which is far away from the substrate; wherein the first electrode and the conductive probe are configured to apply a driving voltage to the dielectric layer to drive the dielectric layer to produce the oxygen vacancy conductive filament.
Optionally, the oxygen sensor comprises a plurality of detection zones, each detection zone of the plurality of detection zones comprising a portion of the dielectric layer; the conductive probe and the first electrode are configured to apply a driving voltage to a portion of the dielectric layer contained in at least one of the plurality of detection zones to drive the portion of the dielectric layer to produce an oxygen-vacancy conductive filament.
Optionally, the oxygen sensor further comprises a modulation layer disposed between the first electrode and the dielectric layer and having heat storage properties and oxygen storage properties.
Optionally, the oxygen sensor further comprises a power supply having a first pole and a second pole configured to apply a driving voltage to the dielectric layer or a detection voltage smaller than the driving voltage to the dielectric layer in a state where the first pole and the second pole are connected to the first electrode and the conductive probe, respectively, and a detection circuit configured to detect a current flowing through the conductive probe and determine the oxygen concentration to be measured based on the detected current.
Optionally, the material of the dielectric layer includes one of hafnium oxide and hafnium aluminum oxide.
Optionally, the dielectric layer has a thickness of 10 to 15 nanometers.
Optionally, the material of the first electrode includes at least one of titanium nitride, platinum, and palladium.
Optionally, the thickness of the first electrode is 30 to 40 nanometers.
Optionally, the material of the modulation layer comprises at least one of titanium, tantalum oxide, hafnium, and aluminum.
Optionally, the thickness of the modulation layer is 40 to 50 nanometers.
Optionally, the end of the conductive probe for applying voltage is circular or rectangular, and the diameter of the circular or the length of the rectangular is more than 1 nanometer and less than 100 micrometers.
At least one embodiment of the present disclosure also provides a method for measuring the oxygen concentration to be measured by using the oxygen sensor. The method comprises the following steps: controlling the conductive probe and the first electrode to apply a driving voltage to the dielectric layer; and performing an oxygen concentration test operation on the dielectric layer to determine the oxygen concentration to be tested.
Optionally, controlling the conductive probe and the first electrode to apply the driving voltage to the dielectric layer comprises: contacting the conductive probe with the dielectric layer; connecting the first electrode with a first pole of a power supply and connecting the conductive probe with a second pole of the power supply to control the power supply to apply a driving voltage to the dielectric layer; performing an oxygen concentration test operation on the dielectric layer, comprising: stopping applying the driving voltage, and detecting a current flowing through the conductive probe every lapse of a predetermined time interval from a timing when the application of the driving voltage is stopped; determining the oxygen concentration to be measured based on the detected current.
Optionally, detecting the current flowing through the conductive probe every predetermined time interval includes: and at each preset time interval, connecting the first electrode with a first pole of a power supply and connecting the conductive probe with a second pole of the power supply, and controlling the power supply to apply a detection voltage smaller than the driving voltage to the dielectric layer so as to detect the current flowing through the conductive probe.
Optionally, determining the oxygen concentration to be measured based on the detected current comprises: determining a rate of change of the current over time based on the detected current; the oxygen concentration to be measured is determined based on the rate of change of the current over time.
Optionally, the oxygen sensor comprises a plurality of detection zones, each detection zone of the plurality of detection zones comprising a portion of the dielectric layer, the conductive probe and the first electrode being configured to apply a driving voltage to the portion of the dielectric layer comprised by at least one detection zone of the plurality of detection zones to drive the portion of the dielectric layer to generate the oxygen vacancy conductive filaments, the method comprising: for each of at least one of the plurality of detection regions: controlling the conductive probe and the first electrode to apply a driving voltage to a portion of the dielectric layer included in the detection region; and performing an oxygen concentration test operation on the portion of the dielectric layer to determine an oxygen concentration of the detection zone, and determining a to-be-tested oxygen concentration based on the oxygen concentration of each of the at least one detection zone.
Optionally, controlling the conductive probe and the first electrode to apply a driving voltage to a portion of the dielectric layer included in the detection region includes: contacting the conductive probe with a portion of the dielectric layer; connecting the first electrode to a first pole of a power supply and connecting the conductive probe to a second pole of the power supply to control the power supply to apply a driving voltage to the portion of the dielectric layer; performing an oxygen concentration test operation on a portion of the dielectric layer to determine an oxygen concentration of the detection zone, comprising: stopping applying the driving voltage, and detecting a current flowing through the conductive probe every lapse of a predetermined time interval from a timing when the application of the driving voltage is stopped; and determining an oxygen concentration of the detection region based on the detected current.
Optionally, determining the oxygen concentration of the detection zone based on the detected current comprises: determining a rate of change of the current over time based on the detected current; the oxygen concentration in the detection zone is determined based on the rate of change of the current over time.
Optionally, detecting the current flowing through the conductive probe every predetermined time interval includes: at each predetermined time interval, connecting the first electrode to a first pole of a power supply and connecting the conductive probe to a second pole of the power supply, and controlling the power supply to apply a detection voltage smaller than the driving voltage to a portion of the dielectric layer to detect a current flowing through the conductive probe.
Optionally, determining the oxygen concentration to be measured based on the oxygen concentration of each of the at least one detection area comprises: and determining the average value or the median value of the oxygen concentration of each detection area in the at least one detection area as the oxygen concentration to be detected.
Drawings
To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below, and it should be apparent that the drawings described below only relate to some embodiments of the present disclosure and are not limiting on the present disclosure.
FIG. 1 is a schematic diagram of an oxygen sensor according to at least one embodiment of the present disclosure;
fig. 2A to 2B are schematic diagrams illustrating a principle of measuring an oxygen concentration to be measured using an oxygen sensor according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of another oxygen sensor in accordance with at least one embodiment of the present disclosure;
FIG. 4 is a schematic diagram of another oxygen sensor in accordance with at least one embodiment of the present disclosure;
FIG. 5 is a schematic diagram of another oxygen sensor in accordance with at least one embodiment of the present disclosure;
FIG. 6 is a flow chart of a method of measuring oxygen concentration using an oxygen sensor in accordance with at least one embodiment of the present disclosure; and
fig. 7 is a flow chart of a method of measuring oxygen concentration using an oxygen sensor according to at least one embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be described below clearly and completely with reference to the accompanying drawings. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.
Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. Also, the use of the terms "a," "an," or "the" and similar referents do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that the element or item preceding the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
The oxygen sensor is used for measuring oxygen concentration, the traditional oxygen sensor utilizes an oxygen sensitive ceramic element to measure oxygen potential, and corresponding oxygen concentration is calculated according to a chemical equilibrium principle, but the oxygen sensor is complex to prepare, short in service life and incapable of being reused. In view of this, the present disclosure provides a novel oxygen sensor with simple structure, easy preparation, long service life and reusability.
Fig. 1 is a schematic structural diagram of an oxygen sensor 100 according to at least one embodiment of the present disclosure.
Referring to fig. 1, the oxygen sensor 100 includes a substrate 110, a first electrode 120, a dielectric layer 130, and a conductive probe 140. For example, the substrate 110 may be a rigid substrate or a flexible substrate, for example, the rigid substrate may be a silicon wafer, a sapphire substrate, silicon carbide, a glass substrate, a ceramic substrate, a plastic substrate, and the like, and the flexible substrate may be a plastic substrate (e.g., a polyimide substrate), a resin substrate, and the like, which are not limited in this respect.
The first electrode 120 is disposed on the substrate 110, and may be an electrode formed of a metal material such as platinum or palladium or an alloy material such as titanium nitride. The thickness of the first electrode 120 is about 30 nm to 40 nm, such as 32 nm, 35 nm, or 38 nm.
A dielectric layer 130 is disposed on a side of the first electrode 120 away from the substrate 110, and a material of the dielectric layer 130 is a material in which oxygen vacancies can be generated, and when a voltage is applied, the oxygen vacancies in the interior thereof can be aggregated to form an oxygen-vacancy conductive filament. For example, the material of the dielectric layer 130 may be one of materials with similar properties, such as hafnium oxide and hafnium aluminum oxide. Dielectric layer 130 has a thickness of about 10nm to about 15 nm, such as 12 nm or 13 nm.
The conductive probe 140 may be made of a conductive material such as tungsten or tungsten alloy. In addition, if the cost is not considered, the surface of the probe made of metal or silicon can be plated with conductive materials such as titanium oxide, platinum, gold and the like. The conductive probes 140 are disposed to contact the dielectric layer 130 and also to be spaced apart from the dielectric layer 130. For example, first electrode 120 and conductive probe 140 are configured to apply a drive voltage U to dielectric layer 1300To drive the dielectric layer 130 to produce oxygen vacancy conductive filaments.
For example, the leads 121 and 141 for connecting a power source are disposed on the first electrode 120 and the conductive probe 140, respectively, and when the lead 121 of the first electrode 120 and the lead 141 of the conductive probe 140 are connected to a first pole and a second pole (e.g., a positive pole and a negative pole) of the power source, respectively, a driving voltage U may be applied to the dielectric layer 1300To drive the dielectric layer 130 to produce oxygen vacancy conductive filaments.
For example, the end of the conductive probe 140 may be circular, rectangular or other shape that can provide a certain contact area between the conductive probe 140 and the dielectric layer 130, and the end shape may be set to any size according to the requirement, and is generally greater than 1 nm and smaller than 100 microns, such as 5 nm, 500 nm, 1 micron or 10 microns. For example, when the end is circular, the diameter of the circle is greater than 1 nm and less than 100 microns, when the end is rectangular, the length of the rectangle is greater than 1 nm and less than 100 microns, and when the end is square, the side of the square is greater than 1 nm and less than 100 microns. At this time, the end of the conductive probe 140 may have a sufficient contact area with the dielectric layer 130 to apply a sufficient voltage to sufficiently form the oxygen-vacancy conductive filament.
The oxygen sensor 100 described above has advantages of a small volume and a simple structure, and compared to the conventional oxygen sensor using an oxygen sensitive ceramic element that requires complex processes such as granulation, sizing, electrode coating, sintering, and the like, the oxygen sensor 100 can be formed by a simple manufacturing process such as deposition, sputtering, and the like.
Fig. 2A to 2B are schematic diagrams illustrating the principle that the oxygen sensor 100 measures the oxygen concentration to be measured according to an embodiment of the disclosure.
Referring to FIG. 2A, a dielectric layer 130 of an oxygen sensor 100 is shown when a driving voltage U is applied0The state (only oxygen vacancies are shown in the figure, and oxygen ions are not shown). The material of the dielectric layer 130 may be one of materials with similar properties, such as hafnium oxide, hafnium aluminum oxide, and the like. Referring to fig. 1, when the lead 121 of the first electrode 120 and the lead 141 of the conductive probe 140 are connected to a first pole and a second pole (e.g., a positive pole and a negative pole) of a power supply, respectively, and the end of the conductive probe 140 contacts the dielectric layer 130, an oxygen vacancy conductive filament is generated in the dielectric layer 130 by controlling the magnitude of a voltage applied to the dielectric layer 130 by the power supply via the conductive probe 140 and the first electrode 120, which may be a built-in power supply of the oxygen sensor 100 (as shown at 450 in fig. 4) or an external power supply that may be connected to the oxygen sensor to supply power thereto.
For example, a drive voltage U of about 5V is applied to the dielectric layer 130 made of hafnium oxide0In time, oxygen atoms in dielectric layer 130 ionize into oxygen vacancies and oxygen ions, creating a plurality of oxygen vacancies 210, and these oxygen vacancies converge together to form oxygen-vacancy conductive filaments 211 and 212. The oxygen vacancy conductive filaments 211 and 212 are communicated with the upper conductive probe 140 and the first electrode 120, and the more oxygen vacancy conductive filaments are generated in the dielectric layer 130, the stronger the conductive capability of the whole dielectric layer 130 is, and the smaller the resistance thereof is; on the contrary, in the dielectric layer 130The less oxygen vacancy conductive filaments are generated, the weaker the conductive capability of the dielectric layer 130 as a whole, and the larger the resistance thereof. Note that only two oxygen-vacancy conductive filaments are shown in fig. 2A for convenience of illustration, and in fact the number of oxygen-vacancy conductive filaments may be more, and embodiments of the present disclosure are not limited thereto.
Referring to FIG. 2B, it is shown that dielectric layer 130 in oxygen sensor 100 is being stopped from being applied with drive voltage U0The latter state. After the state of fig. 2A is passed, the driving voltage U applied to the dielectric layer 130 is stopped0For example, the power is turned off, and at this time, oxygen atoms dispersed in the atmosphere penetrate into the inside of the dielectric layer 130 through the surface of the dielectric layer 130 to undergo a reduction reaction with oxygen vacancies contained in the oxygen-vacancy conductive filament, so that the oxygen vacancies contained in the oxygen-vacancy conductive filament are gradually reduced and the conductivity of the dielectric layer 130 is gradually reduced, thereby the resistance R of the dielectric layer 130 is gradually reduced1The resistance R of the dielectric layer 130 increases until the oxygen vacancies contained in the oxygen-vacancy conductive filaments are reduced to some extent1Remain maximum and no longer change.
Meanwhile, the oxygen concentration to be measured in the environment and the resistance R of the dielectric layer 1301The rate of change over time (i.e., the amount of change in resistance per unit time) is related. The higher the concentration of oxygen to be measured in the environment, the more oxygen atoms are permeated into the dielectric layer 130 from the surface of the dielectric layer 130 within a predetermined time interval Δ t (e.g., 1 second), the more oxygen vacancies are reduced in the oxygen vacancy conductive filament within the predetermined time interval Δ t, and thus the greater the amount of change in the resistance of the dielectric layer 130 within the predetermined time interval Δ t. Therefore, the oxygen concentration to be measured in the environment and the resistance R of the dielectric layer 130 can be known1The time rate of change is proportional, in other words, the concentration of oxygen to be measured in the environment is proportional to the current I of the dielectric layer 1301The rate of change over time is proportional.
Due to measurement I1Conveniently, the detection voltage U may be applied to the dielectric layer 130 at predetermined time intervals Δ t1To measure the current I flowing through the conductive probe 1401Then, according to the current I1And deducing the concentration of the oxygen to be measured in the environment according to the change rate of the time. Example (b)For example, in the state shown in fig. 2B, the conductive probe 140 is contacted with the dielectric layer 130, and the power supply is controlled to apply a suitable detection voltage U to the dielectric layer 1301The conductive probe 140, the dielectric layer 130 and the first electrode 120 form a current loop, and the current I flowing through the conductive probe 140 can be read by an ammeter1. It should be noted that the detection voltage U1Is merely for convenience in detecting the current I flowing through the conductive probe 1401The applied voltage is small enough, for example, at least smaller than the driving voltage U0To avoid oxygen vacancy conductive filaments in dielectric layer 130 from being altered by factors other than oxygen in the environment. For example, for dielectric layer 130 of hafnium oxide, a detection voltage U of about 0.2V may be used1。
For example, fig. 3 is a schematic diagram of another oxygen sensor 300, in accordance with at least one embodiment of the present disclosure.
Referring to fig. 3, a substrate 310, a first electrode 320, a lead 321 of the first electrode, a dielectric layer 330, a conductive probe 340, and a lead 341 of the conductive probe in the oxygen sensor 300 are substantially the same as the substrate 110, the first electrode 120, the lead 121 of the first electrode, the dielectric layer 130, the conductive probe 140, and the lead 141 of the conductive probe in the oxygen sensor 100 of fig. 1, respectively. The difference from the oxygen sensor 100 is that the oxygen sensor 300 further includes a modulation layer 350, the modulation layer 350 is disposed between the first electrode 320 and the dielectric layer 330 and has a heat storage property and an oxygen storage property, and for example, a material of the modulation layer 350 may be at least one of titanium, tantalum oxide, hafnium, and aluminum. The modulation layer 350 has a thickness of about 40 nm to about 50 nm, such as 42 nm, 45 nm, or 48 nm.
The principle of measuring the concentration of oxygen to be measured using the oxygen sensor 300 is substantially the same as the principle of measuring the concentration of oxygen to be measured using the oxygen sensor 100 described in conjunction with fig. 2A to 2B. To avoid repetition, further description is omitted here.
In addition to the advantages of small volume and simple structure similar to those of the oxygen sensor 100, the oxygen sensor 300 described above further includes the modulation layer 350, which can enhance the uniformity of the oxygen vacancy conductive filaments generated by the dielectric layer 330, so that the resistance change rate of the dielectric layer 330 is more stable, and the measurement accuracy of the oxygen concentration is improved.
For example, fig. 4 is a schematic diagram of another oxygen sensor 400, in accordance with at least one embodiment of the present disclosure.
Referring to fig. 4, a substrate 410, a first electrode 420, a lead 421 of the first electrode, a dielectric layer 430, a conductive probe 440, and a lead 441 of the conductive probe in the oxygen sensor 400 are substantially the same as the substrate 110, the first electrode 120, the lead 121 of the first electrode, the dielectric layer 130, the conductive probe 140, and the lead 141 of the conductive probe in the oxygen sensor 100 in fig. 1, respectively. The difference from the oxygen sensor 100 is that the oxygen sensor 400 further includes a built-in power supply 450 and a detection circuit 460. The built-in power supply 450 has a first pole 451 and a second pole 452 (e.g., a positive pole and a negative pole), and is configured to apply a driving voltage U to the dielectric layer 430 with the first pole 451 and the second pole 452 connected to the first electrode 420 and the conductive probe 440, respectively0Or less than the drive voltage U0Is detected by voltage U1。
For example, the internal power source 450 is small and the magnitude of the supplied voltage is adjustableThe power supply of (1). The detection circuit 460 is configured to apply a detection voltage U to the dielectric layer 4501In the case of (1), the current I flowing through the conductive probe 440 is detected1And based on the detected current I1And determining the concentration of the oxygen to be detected. For example, the detection circuit 460 may include a current I for measuring current flowing through the conductive probe 4401And for measuring the current I1A calculation circuit (not shown) for determining the oxygen concentration to be measured. The calculation circuit may comprise a programmable chip with calculation capabilities, programmed with means for determining the measured current I1Program instructions for determining the oxygen concentration to be measured.
The principle of measuring the concentration of oxygen to be measured using the oxygen sensor 400 is substantially the same as the principle of measuring the concentration of oxygen to be measured using the oxygen sensor 100 described in conjunction with fig. 2A and 2B. To avoid repetition, further description is omitted here.
The oxygen sensor 400 described above has advantages of small volume, simple structure, etc. similar to those of the oxygen sensor 100, and the built-in power supply 450 and the detection circuit 460 disposed therein improve convenience of use of the oxygen sensor without additionally disposing an external power supply or adopting an inefficient calculation method such as manual calculation.
It is noted that modulation layer 350 depicted in fig. 3 may also be present in oxygen sensor 400 shown in fig. 4, i.e., a structure similar to modulation layer 350 may also be provided between first electrode 410 and dielectric layer 430 to modulate the function of dielectric layer 430 to create an oxygen vacancy-conducting filament.
For example, fig. 5 is a schematic diagram of another oxygen sensor 500 according to at least one embodiment of the present disclosure.
Referring to fig. 5, the substrate 510, the first electrode 520, the lead 521 of the first electrode, the conductive probe 540, and the lead 541 of the conductive probe in the oxygen sensor 500 are substantially the same as the substrate 110, the first electrode 120, the lead 121 of the first electrode, the conductive probe 140, and the lead 141 of the conductive probe in the oxygen sensor 100 in fig. 1, respectively. The difference from the oxygen sensor 100 is that the oxygen sensor 500 includes a plurality of sensing regions, wherein each sensing region comprises a portion of the dielectric layer 530. For example, as shown in fig. 5, taking the example that the oxygen sensor 500 includes 8 detection regions, a first detection region includes a portion 531 of the dielectric layer, a second detection region includes a portion 532 of the dielectric layer, and so on. In other words, the oxygen sensor 500 may be viewed as an integration of a plurality of oxygen sensors 100, the first electrode 520, each portion 531 to 538 of the dielectric layer 530 and the first electrode 520 constituting one single sensing region, the integration of the plurality of single sensing regions constituting the oxygen sensor 500.
The dielectric layer 530 shown in fig. 5 has 8 portions for illustration only, and the number of portions of the dielectric layer 530 may be determined according to the shape and size of the dielectric layer 530 and the shape and size of the end of the conductive probe. For example, in some examples, the dimensions of the first electrode 520 and the dielectric layer 530 may be 200 x 200nm2The end of the conductive probe 540 is circular and the radius of the circle is 10nm, and in this case, the dielectric layer 530 may include 127 portions, i.e., the oxygen sensor 500 may constitute 127 individual detection regions. As another example, in other examples, the dimensions of the first electrode 520 and the dielectric layer 530 may be 1 × 1mm2The ends of the conductive probes 540 are rounded with a radius of 5 μm, and in this case, the dielectric layer may include 12738 portions, i.e., the oxygen sensor 500 may constitute 12738 individual sensing regions.
For example, conductive probe 540 and first electrode 520 are configured to apply a drive voltage U to the portion of dielectric layer 530 contained in each of at least one of the above multiple detection zones0To drive the portion of the dielectric layer 530 to create an oxygen-vacancy conductive filament. That is, conductive probe 540 moves over dielectric layer 530, and when moving to a portion of dielectric layer 530 and applying a driving voltage U to the portion0This portion of dielectric layer 530 then creates an oxygen-vacancy conductive filament. The movement of conductive probe 540 from one portion of dielectric layer 530 to another means that it moves from one detection zone to another. For each detection region, the oxygen concentration to be measured can be measured as in the oxygen sensor 100.
For example, each detection region of the oxygen sensor 500 is similar to one oxygen sensor 100, and thus, for each detection region, the principle of measuring the concentration of oxygen to be measured is substantially the same as the principle of measuring the concentration of oxygen to be measured by the oxygen sensor 100 described in conjunction with fig. 2A to 2B. To avoid repetition, further description is omitted here.
For example, in use, an oxygen concentration measurement may be made for at least one of the plurality of detection zones (e.g. at a plurality of detection zones), and a final oxygen concentration measurement may be obtained from the measurement of the at least one detection zone. For example, after performing a measurement of oxygen concentration on each of at least one of the plurality of detection regions and obtaining a corresponding measurement, statistics of the measurements, such as, but not limited to, an average, a median, etc., may be taken as the measurements of the oxygen sensor 500.
The above-described oxygen sensor 500 takes the statistics of the measurement results of the plurality of detection regions as the final measurement result, improving the accuracy of the measurement results.
It is noted that the modulation layer 350 depicted in fig. 3 and/or the built-in power supply 450, detection circuit 460 depicted in fig. 4 may also be present in the oxygen sensor 500 depicted in fig. 5. For example, a structure similar to that of modulation layer 350 may also be disposed between first electrode 510 and respective portions 531-538 of the dielectric layer to modulate the function of respective portions 531-538 of dielectric layer 530 to create oxygen-vacancy conductive filaments. For another example, a structure similar to the built-in power supply 450 and the detection circuit 460 may be connected between the lead 521 of the first electrode 520 and the lead 541 of the conductive probe 540 to conveniently apply a voltage to the dielectric layer 530 and detect a current flowing through the conductive probe 540. Further, the number of the conductive probes 540 may be more than one, and for example, in the case where a plurality of conductive probes 540 can be configured, a plurality of detection regions of the oxygen sensor 500 may be simultaneously measured using the plurality of conductive probes 540 without moving the one conductive probe 540 to sequentially measure the plurality of detection regions as in the case of only one conductive probe 540, so that the time required to complete the measurement may be reduced.
The structures of the oxygen sensors 100, 300, 400, and 500 according to the embodiments of the present disclosure are described above with reference to fig. 1 to 5, and they measure the concentration of oxygen to be measured in an environment by using the principle that after an oxygen vacancy conductive filament is formed in a dielectric layer thereof, the resistance of the dielectric layer changes due to the permeation of oxygen in the environment, and the higher the oxygen concentration in the environment, the higher the change rate of the resistance with time, and these oxygen sensors use the dielectric layer as an oxygen sensing element, and have the advantages of simple structure, easy preparation, clear working mechanism, small size, long service life, easy operation, accurate measurement result, and the like.
The method of measuring the concentration of oxygen to be measured in the environment using the above-described oxygen sensors 100, 300, 400, and 500 is described in detail below. Since the methods of measuring the oxygen concentration to be measured by the oxygen sensors 100, 300, and 400 are substantially the same, the method of measuring the oxygen concentration to be measured using the oxygen sensor 100 and the oxygen sensor 500 will be described below only by fig. 6 and 7 for the sake of simplicity.
For example, fig. 6 is a flowchart of a method for measuring a concentration of oxygen to be measured using the oxygen sensor 100 provided in accordance with at least one embodiment of the present disclosure.
Referring to fig. 6, the method of measuring the concentration of oxygen to be measured using the oxygen sensor 100 includes steps S610 and S620. In step S610, the conductive probe 140 and the first electrode 120 are controlled to apply a driving voltage U to the dielectric layer 1300. In step S620, an oxygen concentration test operation is performed on the dielectric layer 130 to determine the oxygen concentration to be tested.
For example, step S610 may include sub-step S611 and sub-step S612.
In sub-step S611, the conductive probe 140 is contacted to the dielectric layer 130, and specifically, the end of the conductive probe 140 is contacted to the dielectric layer 130. In the case where the surface of the dielectric layer 130 is not flat, a small pressure may be applied to the end of the conductive probe 140 to have a certain contact area with the dielectric layer 130. For example, the contact area is the area of the conductive probe tip shape. Thus, the first electrode 120, the dielectric layer 130, and the conductive probe 140 may form a metal-insulator-conductive (MIT) structure while constituting a loop.
In sub-step S612, the conductive probe 140 is connected to a first pole (e.g., negative pole) of a power source and the first electrode 120 is connected to a second pole (e.g., positive pole) of the power source to control the power source to apply a driving voltage U to the dielectric layer 1300. For example, for a dielectric layer of hafnium oxide as the material, the drive voltage U0About 5V. The power source may be a built-in power source of the oxygen sensor 100 (as shown at 450 in fig. 4) or may be an external power source connected to the oxygen sensor 100 to supply power thereto. Dielectric layer 130 is applied with a driving voltage U0An oxygen-vacancy conducting filament is then formed as shown in fig. 2A.
For example, step S620 may include sub-step S621 and sub-step S622.
In sub-step S621, the application of the driving voltage U is stopped0And the driving voltage U is applied from the stop0Detects the current I flowing through the conductive probe 140 every predetermined time interval Δ t1. In this step, the current I flowing through the conductive probe 140 is detected every lapse of a predetermined time interval Δ t1The method comprises the following steps: each time a predetermined time interval Δ t has elapsed, the conductive probe 140 is connected to a first pole (e.g., negative pole) of a power source and the first electrode 120 is connected to a second pole (e.g., positive pole) of the power source, and the power source is controlled to apply less than the driving voltage U to the dielectric layer 1300Is detected by voltage U1To detect the current I flowing through the conductive probe 1401. For example, for a dielectric layer made of hafnium oxide, the voltage U is detected1About 0.2V.
For example, the driving voltage U of 5V is applied when the application is stopped for a predetermined time interval Δ t of 1 second0Thereafter, the driving voltage U is applied from the stop0At the time point of (1) and at the time point of (1) after the lapse of (1) a detection voltage U of 0.2V was applied to the dielectric layer1Measuring the current I flowing through the conductive probe 1401＝I11(ii) a From the stop of the application of the driving voltage U0At the time point of (2) and at the time point of (2), a detection voltage U of 0.2V was applied to the dielectric layer1Measuring the current I flowing through the conductive probe 1401＝I12(ii) a From the stop of the application of the driving voltage U0After 3 seconds from the time point of (1) to the dielectric layerApplying a detection voltage U of 0.2V1Measuring the current I flowing through the conductive probe 1401＝I13And so on. The current flowing through the conductive probe 140 may be measured N (N is an integer greater than 1) times at predetermined time intervals Δ t. To make the measurement result more accurate, it is preferable that the time for measuring the current of the conductive probe 140 is within several seconds or several minutes, and if the time is too long (for example, 10 minutes or more), the measurement result may be inaccurate due to the influence of other factors than oxygen.
In sub-step S622, based on the detected current I1And determining the concentration of the oxygen to be detected. In this step, first of all, based on the detected current I1The rate of change of the current over time is determined, and then the oxygen concentration to be measured is determined based on the rate of change of the current over time. If the measurement times are more than 2, obtaining the current I1Taking the average of a plurality of change rates over time as the current I1Rate of change over time.
For example, according to the current I measured in sub-step S62111、I12、I13The current I can be determined first1A rate of change with time of
As mentioned above, the oxygen concentration and current I are measured1The rate of change over time is proportional and therefore can be based on the current I1Determining the oxygen concentration to be measured according to the time change rate
Wherein C is the oxygen concentration to be measured, and k is a proportionality constant. The value of k can be obtained experimentally, for example, by measuring the result of the oxygen concentration to be measured with a conventional oxygen sensor under the same experimental conditions and based on the current I1The rate of change over time calculates the value of k.
For example, method 600 is equally applicable to oxygen sensor 300 and oxygen sensor 400, where substeps S621 and S622 may be performed by detection circuit 460 for oxygen sensor 400.
For example, fig. 7 is a flow chart of a method of measuring a measured oxygen concentration using an oxygen sensor 500 according to at least one embodiment of the present disclosure.
As previously described, the oxygen sensor 500 includes a plurality of detection regions, and the oxygen concentration may be measured by measuring the oxygen concentration for at least one of the plurality of detection regions and taking statistics of these measured oxygen concentrations, including, but not limited to, for example, mean, median, as the final measurement of the oxygen sensor 500.
Referring to fig. 7, the method of measuring the oxygen concentration using the oxygen sensor 500 may include steps S710 to S730. Wherein substeps S710 and S720 are performed for each of at least one of the plurality of detection regions.
In step S710, the conductive probe 540 and the first electrode 520 are controlled to apply a driving voltage U to a portion (e.g., one of the portions 531 to 538 shown in fig. 5) of the dielectric layer 530 included in the detection region0。
For example, step S710 may include substep S711 and substep S712.
In sub-step S711, conductive probe 540 is contacted to a portion (e.g., one of portions 531 to 538 shown in fig. 5) of dielectric layer 530, i.e., an end portion of conductive probe 540 is contacted to the portion of dielectric layer 530. In the case where the surface of the dielectric layer 530 is not flat, a small pressure may be applied to the end of the conductive probe 540 to have a certain contact area with the portion of the dielectric layer 530. For example, the contact area is the area of the conductive probe tip shape.
In sub-step S712, the conductive probe 540 is connected to a first pole (e.g., negative pole) of a power source and the first electrode 520 is connected to a second pole (e.g., positive pole) of the power source to control the power source to apply the driving voltage U to the dielectric layer 5300. The power source may be a built-in power source of the oxygen sensor 500 (as shown at 450 in fig. 4) or an external power source that may be connected to the oxygen sensor 500 to supply power thereto. The portion of dielectric layer 530 is applied with a driving voltage U0Thereafter, the oxygen vacancies in the portion aggregate to form an oxygen-vacancy conductive filament, as shown in the figure2A.
At step S720, an oxygen concentration test operation is performed on the portion of the dielectric layer 530 (e.g., one of the portions 531 to 538 shown in fig. 5) to determine the oxygen concentration of the detection region.
Step S720 may include sub-step S721 and sub-step S722.
In sub-step S721, the application of the driving voltage U is stopped0And the driving voltage U is applied from the stop0Is detected, the current I flowing through the conductive probe 540 is detected every predetermined time interval deltat1. In this step, the current I flowing through the conductive probe 140 is detected every lapse of a predetermined time interval Δ t1The method comprises the following steps: at each predetermined time interval Δ t, the first electrode 520 is connected to a first pole (e.g., positive pole) of a power source and the conductive probe 540 is connected to a second pole (e.g., negative pole) of the power source, and the power source is controlled to apply less than the drive voltage U to the portion of the dielectric layer 5300Is detected by voltage U1To detect the current I flowing through the conductive probe 5401. The operation of this step is similar to the operation of the aforementioned sub-step S621 of the method 600, and is not repeated here to avoid repetition.
In sub-step S722, based on the detected current I1And determining the concentration of the oxygen to be detected. In this step, based on the detected current I1The rate of change of the current over time is determined, and then the oxygen concentration of the portion of the dielectric layer 530 is determined based on the rate of change of the current over time. The operation of this step is similar to the operation of the aforementioned sub-step S622 in the method 600, and is not repeated here to avoid repetition.
In step S730, the oxygen concentration to be measured is determined based on the oxygen concentration of each of the at least one detection area. In this step, statistics of the oxygen concentration of each of the at least one detection area, including but not limited to an average or median of the oxygen concentration of each detection area, are determined as the oxygen concentration to be measured.
For example, the aforementioned steps S710 and S720 are performed on 4 detection regions of the 8 detection regions of the oxygen sensor 500, which correspond to the portions 531, 533, 535, 537 of the dielectric layer 530, respectively, andit is determined in step S720 that the oxygen concentrations of the 4 detection regions are respectively C1、C3、C5And C7. Then in step S730, the average value of the oxygen concentrations of the 4 detection regions may be determined as the oxygen concentration to be measured, i.e., C ═ Mean (C)1,C3,C5,C7) Or determining the Median of the oxygen concentrations in the 4 detection regions as the oxygen concentration to be measured, i.e. C ═ media (C)1,C3,C5,C7)。
As such, embodiments of the present disclosure provide a new type of oxygen sensor that is completely different from conventional oxygen sensors that utilize ceramic sensing elements to measure oxygen concentration, such as the aforementioned oxygen sensors 100, 300, 400, and 500. The oxygen sensors use a material capable of generating oxygen vacancy conductive filaments under a certain voltage as an oxygen sensitive element to achieve the purpose of measuring the oxygen concentration, and have the advantages of simple structure, easiness in preparation, small overall size, repeated use, long service life, accurate detection result and the like.
In addition, the following points need to be explained:
(1) the drawings of the embodiments of the present disclosure relate only to the structures related to the embodiments of the present disclosure, and other structures may refer to general designs.
(2) For purposes of clarity, the thickness of layers or regions in the figures used to describe embodiments of the present disclosure are exaggerated or reduced, i.e., the figures are not drawn on a true scale. It will be understood that when an element such as a layer, region or substrate is referred to as being "on" or "under" another element, it can be "directly on" or "under" the other element or intervening elements may be present.
(3) Without conflict, embodiments of the present disclosure and features of the embodiments may be combined with each other to arrive at new embodiments.
The above description is only for the specific embodiments of the present disclosure, but the scope of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present disclosure, and all the changes or substitutions should be covered within the scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the appended claims and their equivalents.
Claims (10)
1. An oxygen sensor comprising:
a substrate, a first electrode and a second electrode,
a first electrode disposed on the substrate;
the dielectric layer is arranged on one side of the first electrode, which is far away from the substrate; and
a conductive probe is provided on the surface of the substrate,
wherein the first electrode and the conductive probe are configured to apply a driving voltage to the dielectric layer to drive the dielectric layer to produce an oxygen vacancy conducting filament.
2. The oxygen sensor of claim 1,
the oxygen sensor includes a plurality of detection zones, each detection zone of the plurality of detection zones including a portion of the dielectric layer;
the conductive probe and the first electrode are configured to apply the drive voltage to a portion of a dielectric layer contained in at least one detection zone of the plurality of detection zones to drive the portion of the dielectric layer to produce an oxygen-vacancy conductive filament.
3. The oxygen sensor of claim 1, further comprising:
a modulation layer disposed between the first electrode and the dielectric layer and having a heat storage property and an oxygen storage property.
4. The oxygen sensor of claim 1, further comprising a power supply and a detection circuit, wherein,
the power supply has a first pole and a second pole configured to apply the driving voltage to the dielectric layer or apply a detection voltage smaller than the driving voltage to the dielectric layer in a state where the first pole and the second pole are connected to the first electrode and the conductive probe, respectively,
the detection circuit is configured to detect a current flowing through the conductive probe and determine a concentration of oxygen to be measured based on the detected current.
5. The oxygen sensor according to any one of claims 1 to 4,
the material of the dielectric layer comprises one of hafnium oxide and hafnium aluminum oxide.
6. The oxygen sensor of claim 5,
the thickness of the dielectric layer is 10 to 15 nanometers.
7. The oxygen sensor according to any one of claims 1 to 4,
the material of the first electrode comprises at least one of titanium nitride, platinum and palladium.
8. The oxygen sensor of claim 7,
the thickness of the first electrode is 30 to 40 nm.
9. The oxygen sensor of claim 3,
the material of the modulation layer includes at least one of titanium, tantalum oxide, hafnium, and aluminum.
10. The oxygen sensor of claim 9,
the thickness of the modulation layer is 40 to 50 nm.
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