AU2020256373B2 - Humidity sensor chip having three-electrode structure - Google Patents
Humidity sensor chip having three-electrode structure Download PDFInfo
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Abstract
The present invention discloses a humidity sensor chip having a three-electrode structure,
including: a humidity-sensitive module, a measuring circuit module, and a micro processing
unit, where the humidity-sensitive module includes a humidity-sensitive material, a substrate, a
first electrode, a second electrode, and a third electrode; the humidity-sensitive material, the
substrate, the first electrode, the second electrode, and the third electrode constitute a
humidity-sensitive capacitor-resistor composite structure having a three-electrode structure; the
first electrode, the humidity-sensitive material, the substrate, and the third electrode constitute a
capacitor structure, and the humidity-sensitive material and the substrate are a composite
dielectric layer of the capacitor; the second electrode, the humidity-sensitive material, the
substrate, and the third electrode also constitute a capacitor structure, and the humidity-sensitive
material and the substrate are a dielectric layer of the capacitor; and the first electrode, the
humidity-sensitive material, and the second electrode constitute a humidity-sensitive resistor
structure, and the humidity-sensitive material serves as a humidity-sensitive material of the
humidity-sensitive resistor; and the substrate is a crystalline material having a piezoelectric
effect.
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Description
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[0001] The present invention relates to a humidity sensor chip having a three-electrode structure.
[0002] For documents related to the background of a humidity sensor, refer to the following:
[0003] [1] Hosseinbabaei, F. and P. Shabani (2014). "A gold/organic semiconductor diode for
ppm-level humidity sensing." Sensors and Actuators B-chemical 205: 143-150.
[0004] [2] Hosseini, M. S. and S. Zeinali (2019). "Capacitive humidity sensing using a metal-organic framework nanoporous thin film fabricated through electrochemical in situ
growth." Journal of Materials Science: Materials in Electronics 30(4): 3701-3710.
[0005] [3] Jeong, W., J. Song, et al. (2019). "Breathable Nanomesh Humidity Sensor for Real-time Skin Humidity Monitoring." ACS Applied Materials & Interfaces 11(47):
44758-44763.
[0006] [4] Kuang, Q., C. Lao, et al. (2007). "High-sensitivity humidity sensor based on a
single Sn02 nanowire." Journal of the American Chemical Society 129(19): 6070-6071.
[00071 [5] Li, L., F. Vilela, et al. (2009). "Miniature humidity micro-sensor based on organic conductive polymer-poly(3,4-ethylenedioxythiophene)." Micro & Nano Letters 4(2): 84-87.
[0008] [6] Popov, V. I., D. V. Nikolaev, et al. (2017). "Graphene-based humidity sensors: the
origin of alternating resistance change." Nanotechnology 28(35): 355501.
[0009] [7] Su, P. and C. Uen (2005). "A resistive-type humidity sensor using composite films
prepared from poly(2-acrylamido-2-methylpropane sulfonate) and dispersed organic silicon
sol." Talanta 66(5): 1247-1253.
[0010] [8] Zhang, C., W. Zhang, et al. (2010). "Optical fibre temperature and humidity sensor." Electronics Letters 46(9): 643-644.
[0011] An objective of the present invention is to provide a humidity sensor chip having a three-electrode structure, capable of further performing self-diagnosis and replacement prompting of the humidity sensor chip.
[0012] A specific technical solution for achieving the objective of the present invention is: a humidity sensor chip, including a humidity-sensitive module, where the humidity-sensitive
module includes a humidity-sensitive material, a substrate, an upper electrode, and a lower
electrode; the lower electrode is located on a back face of a material of the substrate, the
humidity-sensitive material is prepared on a front face of the substrate, and the upper electrode
is located on an upper face of the humidity-sensitive material; and the humidity-sensitive
material is characterized in that the humidity-sensitive material has a water absorbing property
and absorbs water in ambient air, causing resistivity to vary with a water content. The
humidity-sensitive material is an organic material, an inorganic material, or an
organic-inorganic composite material.
[0013] In some implementations, the sensor chip includes: a humidity-sensitive module, a measuring circuit module, and a micro processing unit. In some implementations, the sensor
chip includes: a humidity-sensitive module, a measuring circuit module, a storage module, and
a micro processing unit.
[0014] In some implementations, the humidity-sensitive module includes a humidity-sensitive
material, a substrate, an upper electrode, and a lower electrode, where the humidity-sensitive
material is a mixture formed after adding 5 to 8% by weight of cuprous oxide, 4 to 7% by
weight of zinc oxide, and 4 to 8% by weight of 4-epoxypropanoxycarbazole into phenyl
benzoate, and performing vigorous stirring at 90 to 110°C, that is,
a precursor solution of the humidity-sensitive material is a hydrophobic oily mixture
including cuprous oxide, zinc oxide, 4-epoxypropanoxycarbazole (CAS number: 53-95-2), and
phenyl benzoate.
[0015] Preferably, cuprous oxide is granular cuprous oxide having a size of 1 to 10 m, and zinc oxide is rod-shaped zinc oxide having a size of 0.5 to 5 m.
[0016] Preferably, a weight part of cuprous oxide is from 5 to 8%, a weight part of zinc oxide
is from 4 to 7%, a weight part of 4-epoxypropanoxycarbazole is from 3 to 6%, and the
remaining part is phenyl benzoate.
[0017] The method for preparing the humidity-sensitive module includes the following steps:
(a) preparing a precursor solution of the humidity-sensitive material: adding 5 to 8% by weight of cuprous oxide, 4 to 7% by weight of zinc oxide, and 4 to 8% by weight of 4-epoxypropanoxycarbazole into phenyl benzoate; and heating the mixture to 90 to 110°C, and performing vigorous stirring for 30 to 60 minutes by using a magnetic stirrer to form a hydrophobic oily mixture; (b) preparing the humidity-sensitive material on a front face of a substrate: spin-coating the hydrophobic oily mixture obtained in step (a) on the front face of the substrate at 90 to 110°C, and then naturally cooling to room temperature; (c) preparing a third electrode on a back face of the substrate by using an evaporation process, a sputtering process, or a radio-frequency magnetron sputtering process; and (d) preparing, by using a mask, a first electrode and a second electrode on the front face of the substrate by using an evaporation process, a sputtering process, or a radio-frequency magnetron sputtering process.
[0018] Optionally, step (c) is adjusted to be before step (a).
[0019] In all implementations of the present invention, the humidity-sensitive module includes a humidity-sensitive material, a substrate, a first electrode, a second electrode, and a third electrode, and the humidity-sensitive material, the substrate, the first electrode, the second electrode, and the third electrode constitute a humidity-sensitive capacitor-resistor composite structure having a three-electrode structure, that is: a humidity-sensitive resistor is constituted between the first electrode and the second electrode, a humidity-sensitive capacitor is constituted between the first electrode and the third electrode, a humidity-sensitive capacitor is also constituted between the second electrode and the third electrode, and there is a same humidity-sensitive material between every two of the first electrode, the second electrode, and the third electrode.
[0020] The substrate is a crystalline material having a piezoelectric effect.
[0021] In the present invention, the humidity sensor measures an ambient air humidity through the following implementation: the measuring circuit module is configured to perform the following two measurement operations during measurement, where a sequence of the two measurement operations is not limited: (1) applying, by the measuring circuit module, an alternating-current excitation signal having a variable frequency within a preset frequency range to the first electrode and the third electrode of the humidity-sensitive module or applying an alternating-current excitation signal to the second electrode and the third electrode of the humidity-sensitive module, to measure a resonant frequency of the humidity-sensitive module; and
(2) applying, by the measuring circuit module, a direct-current signal to the first
electrode and the second electrode of the humidity-sensitive module, to measure a
humidity-sensitive resistance value of the humidity-sensitive module, where
the resonant frequency and the humidity-sensitive resistance value vary with a water
content of the humidity-sensitive material;
the measuring circuit module transmits the resonant frequency and the
humidity-sensitive resistance value of the humidity-sensitive module that are measured to the
micro processing unit; and
the micro processing unit calculates two ambient air humidity reference values, namely,
an ambient air humidity reference value a and an ambient air humidity reference value b,
respectively according to the resonant frequency and the humidity-sensitive resistance value;
and
preferably, a root mean square value or a mean value of the ambient air humidity
reference value a and the ambient air humidity reference value b is output as a result.
[0022] The humidity sensor chip implements self-diagnosis and replacement prompting.
Specifically, the determining function module in the micro processing unit implements the
following determination function: the determining function module performs self-diagnosis
according to the ambient air humidity reference value a and the ambient air humidity reference
value b that are obtained through calculation to determine whether the humidity sensor chip has
a fault or aged performance.
[0023] During the research on the present invention, the inventor finds that two different
physical properties of some humidity-sensitive modules vary with the water content of the
humidity-sensitive material. The two physical properties are both closely related to the water
content of the humidity-sensitive material, and can both be used to detect the humidity in the
ambient air. The inventor also finds that: due to the two different physical properties, physical
mechanisms according to which the two different physical properties vary with the water
content are different; and after the humidity-sensitive module is constructed, the two different
physical properties that are closely related to the water content of the humidity-sensitive material also have inconsistent performance degradation curves as a use time of the humidity sensor increases, that is, the different physical properties that are related to the humidity-sensitive material have increasingly large deviations in terms of measurement accuracy as the use time of the sensor increases, and their degrees of deviation are inconsistent.
[0024] In the present invention, the ambient air humidity is detected by using humidity sensitivity of resistivity of some humidity-sensitive materials. In addition, the inventor
inventively proposes that: the humidity-sensitive module includes a humidity-sensitive material,
a substrate, a first electrode, a second electrode, and a third electrode; the humidity-sensitive
material, the substrate, the first electrode, the second electrode, and the third electrode
constitute a humidity-sensitive capacitor-resistor composite structure having a three-electrode
structure; the first electrode, the humidity-sensitive material, the substrate, and the third
electrode constitute a capacitor structure, and the humidity-sensitive material and the substrate
are a composite dielectric layer of the capacitor; the second electrode, the humidity-sensitive
material, the substrate, and the third electrode also constitute a capacitor structure, and the
humidity-sensitive material and the substrate are a dielectric layer of the capacitor.
[0025] When an alternating-current excitation signal having a specific frequency is applied to
the capacitor, the capacitor has mechanical oscillations, and resonant frequency sensitivity of
the mechanical oscillations depends on humidity of the ambient air. This is because the quartz
flakes have a piezoelectric property, when the alternating-current excitation signal of the
specific frequency is applied to the quartz flakes, the quartz flakes have mechanical oscillations,
and resonant frequency sensitivity of the mechanical oscillations depends on cutting directions,
sizes, and mass of the quartz flakes, and after water molecules are absorbed by the
humidity-sensitive material, mass of the humidity-sensitive material attached to the quartz
flakes is changed, so that when the altemating-current excitation signal of the specific
frequency is applied to the capacitor, the resonant frequency sensitivity depends on the
humidity of the ambient air.
[0026] Therefore, in the humidity sensor chip having a three-electrode structure of the present
invention, when the ambient air humidity is measured, the following two physical properties of
the humidity sensitive module created in the present invention are both utilized:
(I) the resonant frequency of the humidity-sensitive module varies with the water
content of the humidity-sensitive material; and (II) the humidity-sensitive resistance value of the humidity-sensitive module varies with the water content of the humidity-sensitive material.
[0027] In addition, the two physical properties have different physical mechanisms, have inconsistent performance degradation curves as the use time of the humidity sensor increases, and can be used to implement self-diagnosing and replacement prompting functions of the humidity sensor.
[0028] A solution of the present invention is implemented by using the physical property that the humidity-sensitive resistance value of the humidity-sensitive module varies with the water content of the humidity-sensitive material. In this solution, a value of the ambient air humidity is calculated by the micro processing unit according to a formula without using an independent storage module, so that costs of the humidity sensor chip can be lowered. Another solution of the present invention is implemented by using the physical property that a capacitance value (dielectric constant) of the humidity-sensitive module varies with the water content of the humidity-sensitive material, and in the solution, an independent storage module recording standard curves of the two different physical properties of the humidity-sensitive module that vary with the water content of the humidity-sensitive material is included, and the ambient air humidity is determined through comparison with the curves.
[0029] In all the implementations of the present invention, the humidity-sensitive material, the substrate, the first electrode, the second electrode, and the third electrode constitute a humidity-sensitive capacitor-resistor composite structure having a three-electrode structure. A humidity-sensitive resistor is constituted between the first electrode and the second electrode, a humidity-sensitive capacitor is constituted between the first electrode and the third electrode, a humidity-sensitive capacitor is also constituted between the second electrode and the third electrode, and there is a same humidity-sensitive material between every two of the first electrode, the second electrode, and the third electrode.
[0030] In the present invention, the humidity-sensitive material is a mixture formed after adding 5 to 8% by weight of cuprous oxide, 4 to 7% by weight of zinc oxide, and 4 to 8% by
weight of 4-epoxypropanoxycarbazole into phenyl benzoate, and performing vigorous stirring.
[0031] In the present invention, the provided organic/inorganic composite humidity-sensitive material is a hydrophobic humidity-sensitive material, to prevent a humidity-sensitive sensing layer from being stripped off because of being dissolved in water under a relatively high humidity condition.
[0032] In the present invention, in a preferable technical solution, an electronic switch controlled by the micro processing unit is disposed between the first electrode and the second
electrode, where the electronic switch is a transmission gate made up of a pair of transistors,
that is, a PMOS and an NMOS; a control end of the transmission gate is connected to the micro
processing unit; and when a resonant frequency of the humidity-sensitive module is measured,
the electronic switch is controlled by the micro processing unit to be in an on state, to
short-circuit the first electrode and the second electrode, and the electronic switch keeps an off
state in the remaining time.
[0033] In the present invention, in a preferable technical solution, a temperature sensor is further integrated in the humidity-sensitive module, the temperature sensor is connected to the
measuring circuit module, the measuring circuit module transmits a measured temperature
value of the humidity-sensitive material to the micro processing unit, and the micro processing
unit corrects a measured ambient air humidity value according to the temperature value. The
inventor finds that the temperature affects the relative humidity of a designated environmental
space.
[0034] During self-diagnosis, the humidity sensor chip of the present invention can implement
self-diagnosis by using only its own properties without using any external reference standards
outside the humidity sensor chip.
[0035] FIG. 1 is a front view of a humidity sensor chip;
[0036] FIG. 2 is a schematic three-dimensional view of a humidity sensor chip;
[0037] FIG. 3 is a diagram of another humidity sensor chip (in the figure, quartz flakes are
below a humidity-sensitive material and are not shown); and
[0038] FIG. 4 shows a capacitor-resistor composite structure of a humidity-sensitive module
of the humidity sensor chip in FIG. 2 or FIG. 3.
[0039] Reference signs in the figures are as follows: 1-first electrode, 2-second electrode,
3-third electrode, 4-humidity-sensitive material, and 5-substrate.
[0040] The technical solutions of the present invention are specifically described below with reference to examples.
[0041] A humidity sensor chip includes: a humidity-sensitive module, a measuring circuit module, and a micro processing unit.
[0042] In some implementations, the humidity-sensitive material is an organic material. In some implementations, the humidity-sensitive material is an inorganic material. In some implementations, the humidity-sensitive material is an organic-inorganic composite material.
[0043] In some implementations, there is no independent storage module. In such implementations, the humidity-sensitive module includes a humidity-sensitive material 4, a substrate 5, a first electrode 1, a second electrode 2, and a third electrode 3. The humidity-sensitive material 4, the substrate 5, the first electrode 1, the second electrode 2, and the third electrode 3 constitute a humidity-sensitive capacitor-resistor composite structure having a three-electrode structure, as shown in FIG. 2.
[0044] The humidity-sensitive module and the micro processing unit are integrated on a substrate material by using a package on package technology, to obtain the humidity sensor chip. A humidity-sensitive resistor is constituted between the first electrode and the second electrode, a humidity-sensitive capacitor is constituted between the first electrode 1 and the third electrode 3, a humidity-sensitive capacitor is also constituted between the second electrode 2 and the third electrode 3, and there is a same humidity-sensitive material between every two of the first electrode 1, the second electrode 2, and the third electrode 3. The humidity-sensitive material is prepared on a front face of the substrate 5, the first electrode 1 and the second electrode 2 are both located on an upper face of the humidity-sensitive material, and the third electrode 3 is located on a back face of the substrate 4. The first electrode 1 and the second electrode 2 are a pair of electrodes surrounding each other without being in contact with each other and having the humidity-sensitive material therebetween.
[0045] The first electrode 1, the humidity-sensitive material 4, the substrate 5, and the third electrode 3 constitute a capacitor structure, and the humidity-sensitive material 4 and the substrate 5 are a composite dielectric layer of the capacitor. The second electrode 2, the humidity-sensitive material 4, the substrate 5, and the third electrode 3 also constitute a capacitor structure, and the humidity-sensitive material 4 and the substrate 5 are a dielectric layer of the capacitor. The first electrode 1, the humidity-sensitive material 4, and the second electrode 2 constitute a humidity-sensitive resistor structure, and the humidity-sensitive material 4 serves as a humidity-sensitive material of the humidity-sensitive resistor.
[0046] In such implementations, the micro processing unit calculates two ambient air humidity reference values, namely, an ambient air humidity reference value a and an ambient air humidity reference value b, respectively from the resonant frequency and the humidity-sensitive resistance value according to a preset formula.
[0047] In some implementations, the sensor chip includes: a humidity-sensitive module, a measuring circuit module, a micro processing unit, and a storage module. That is, compared with the foregoing implementations, an independent storage module is added, where the storage module is configured to store a standard parameter library. In such implementations, the humidity-sensitive module includes a humidity-sensitive material 4, a substrate 5, a first electrode 1, a second electrode 2, and a third electrode 3. The humidity-sensitive material 4, the substrate 5, the first electrode 1, the second electrode 2, and the third electrode 3 constitute a humidity-sensitive capacitor-resistor composite structure having a three-electrode structure. The humidity-sensitive module, the micro processing unit, the measuring circuit module, and the storage module are integrated on the substrate 5 by using a package on package technology, to obtain the humidity sensor chip. A humidity-sensitive resistor is constituted between the first electrode 1 and the second electrode 2, a humidity-sensitive capacitor is constituted between the first electrode 1 and the third electrode 3, a humidity-sensitive capacitor is also constituted between the second electrode 2 and the third electrode 3, and there is a same humidity-sensitive material between every two of the first electrode 1, the second electrode 2, and the third electrode 3, as shown in FIG. 2.
[0048] The humidity-sensitive material 4 is prepared on a front face of the substrate 5, the first electrode 1 and the second electrode 2 are both located on an upper face of the humidity-sensitive material 4, and the third electrode 3 is located on a back face of the substrate 5. The first electrode 1 and the second electrode 2 are a pair of electrodes surrounding each other without being in contact with each other and having the humidity-sensitive material therebetween. The first electrode 1, the humidity-sensitive material 4, the substrate 5, and the third electrode 3 constitute a capacitor structure, and the humidity-sensitive material 4 and the substrate 5 are a composite dielectric layer of the capacitor. The second electrode 2, the humidity-sensitive material 4, the substrate 5, and the third electrode 3 also constitute a capacitor structure, and the humidity-sensitive material 4 and the substrate 5 are a dielectric layer of the capacitor. The first electrode 1, the humidity-sensitive material 4, and the second electrode 2 constitute a humidity-sensitive resistor structure, and the humidity-sensitive material serves as a humidity-sensitive material of the humidity-sensitive resistor.
[0049] In such implementations, the storage module stores a standard parameter library, and the standard parameter library records both standard curves of the resonant frequency and the
humidity-sensitive resistance value of the humidity-sensitive module that vary with a water
content of the humidity-sensitive material.
[0050] The micro processing unit performs, according to the resonant frequency and the humidity-sensitive resistance value of the humidity-sensitive module that are measured,
indexing, comparison, and calculation respectively on the standard curves of the resonant
frequency and the humidity-sensitive resistance value of the humidity-sensitive module that
vary with the water content of the humidity-sensitive material and that are recorded in the
standard parameter library, to obtain the ambient air humidity reference value a and the ambient
air humidity reference value b respectively.
[0051] In all implementations, preferably, the substrate is a crystalline material having a piezoelectric effect.
[0052] In all implementations, preferably, the first electrode 1 and the second electrode 2 are a
pair of interdigital electrodes shown in FIG. 1 and FIG. 2, a pair of spiral electrodes shown in
FIG. 3, or a pair of swiss-roll electrodes.
[0053] In all implementations, preferably, the first electrode 1, the second electrode 2, and the
third electrode 3 are gold electrodes or silver electrodes.
[0054] In some implementations, the first electrode 1, the second electrode 2, and the third
electrode 3 are all prepared by using an evaporation process.
[0055] In some implementations, the first electrode 1, the second electrode 2, and the third
electrode 3 are all prepared by using a sputtering process.
[0056] In some implementations, the first electrode 1, the second electrode 2, and the third
electrode 3 are all prepared by using a radio-frequency magnetron sputtering process.
[0057] In all implementations, preferably, the humidity-sensitive material is a hydrophobic
material, to prevent a humidity-sensitive sensing layer from being stripped off because of being
dissolved in water under a relatively high humidity condition.
[0058] In an example, a precursor solution of the humidity-sensitive material is a hydrophobic oily mixture including cuprous oxide, zinc oxide, 4-epoxypropanoxycarbazole (CAS number:
53-95-2), and phenyl benzoate.
[0059] Preferably, cuprous oxide is granular cuprous oxide having a size of 1 to 10 m, and zinc oxide is rod-shaped zinc oxide having a size of 0.5 to 5 m.
[0060] Preferably, a weight part of cuprous oxide is from 5 to 8%, a weight part of zinc oxide is from 4 to 7%, a weight part of 4-epoxypropanoxycarbazole is from 3 to 6%, and the
remaining part is phenyl benzoate.
[0061] The hydrophobicity of phenyl benzoate and 4-epoxypropanoxycarbazole is used therein. Cuprous oxide and zinc oxide are used as the humidity-sensitive material.
[0062] The method for preparing the humidity-sensitive module includes the following steps: (a) preparing a precursor solution of the humidity-sensitive material: adding 5 to 8% by
weight of cuprous oxide, 4 to 7% by weight of zinc oxide, and 4 to 8% by weight of
4-epoxypropanoxycarbazole into phenyl benzoate; and heating the mixture to 90 to 110°C, and
performing vigorous stirring for 30 to 60 minutes by using a magnetic stirrer to form a
hydrophobic oily mixture;
(b) preparing the humidity-sensitive material on a front face of a substrate: spin-coating
the hydrophobic oily mixture obtained in step (a) on the front face of the substrate at 90 to
110°C, and then naturally cooling to room temperature;
(c) preparing a third electrode on a back face of the substrate by using an evaporation
process, a sputtering process, or a radio-frequency magnetron sputtering process; and
(d) preparing, by using a mask, a first electrode and a second electrode on the front face
of the substrate by using an evaporation process, a sputtering process, or a radio-frequency
magnetron sputtering process.
[0063] Optionally, step (c) is adjusted to be before step (a).
[0064] The humidity-sensitive module includes a humidity-sensitive material, a substrate, an
upper electrode, and a lower electrode, where the humidity-sensitive material is a mixture
formed after adding 5 to 8% by weight of cuprous oxide, 4 to 7% by weight of zinc oxide, and 4
to 8% by weight of 4-epoxypropanoxycarbazole into phenyl benzoate, and performing vigorous
stirring at 90 to 110°C.
[0065] In all implementations, preferably, an electronic switch controlled by the micro
processing unit is disposed between the first electrode 1 and the second electrode 2, when a resonant frequency of the humidity-sensitive module is measured, the electronic switch is controlled by the micro processing unit to be in an on state, to short-circuit the first electrode 1 and the second electrode 2, and the electronic switch keeps an off state in the remaining time.
Preferably, the electronic switch is a transmission gate made up of a pair of transistors, that is, a
PMOS and an NMOS. A control end of the transmission gate is connected to the micro
processing unit.
[0066] As shown in FIG. 4, K is the electronic switch, and the electronic switch is controlled by the micro processing unit. The first electrode 1, the humidity-sensitive material 4, the
substrate 5 (quartz flakes), and the third electrode 3 constitute a capacitor structure Cl. The
second electrode 2, the humidity-sensitive material 4, the substrate 5 (quartz flakes), and the
third electrode 3 also constitute a capacitor structure C2. The first electrode 1, the
humidity-sensitive material 4, and the second electrode 2 constitute a humidity-sensitive
resistor R.
[0067] In all implementations, preferably, a temperature sensor is further integrated in the
humidity-sensitive module, the temperature sensor is connected to the measuring circuit
module, the measuring circuit module transmits a measured temperature value of the
humidity-sensitive material to the micro processing unit, and the micro processing unit corrects
a measured ambient air humidity value according to the temperature value. Correction of the
measured humidity value by using the temperature can be performed by using an empirical
formula, and a person skilled in the art is able to implement the correction according to the
description of the present invention. Details are not described therein again.
[0068] In all implementations, the measuring circuit module is configured to perform the
following two measurement operations during measurement, where a sequence of the two
measurement operations is not limited:
[0069] (1) The measuring circuit module applies an alternating-current excitation signal
having a variable frequency within a preset frequency range to the first electrode and the third
electrode of the humidity-sensitive module, to measure a resonant frequency of the
humidity-sensitive module, where as shown in FIG. 4, the altemating-current excitation signal
is applied between two points A and G, and the electronic switch K is in an off state.
[0070] Alternatively, the measuring circuit module applies an alternating-current excitation
signal having a variable frequency within a preset frequency range to the second electrode and the third electrode of the humidity-sensitive module, to measure a resonant frequency of the humidity-sensitive module, where as shown in FIG. 4, the altemating-current excitation signal is applied between two points B and G, and the electronic switch K is in an off state.
[0071] In this step, the electronic switch is controlled by the micro processing unit to be in an on state, to short-circuit the first electrode, and the second electrode, and the measuring circuit module applies the altemating-current excitation signal having the variable frequency within the preset frequency range to the first electrode, the second electrode, and the third electrode of the humidity-sensitive module, to measure the resonant frequency of the humidity-sensitive module, where as shown in FIG. 4, in this case, an equivalent circuit of the humidity sensitive module on the left changes into a form of a simple capacitor C on the right, that is, the electronic switch K is in an on state, the alternating-current excitation signal is equivalent to being applied between A and G, and C is equivalent to an equivalent capacitor of connecting C1 and C2 in parallel.
[0072] (2) The electronic switch, as being controlled by the micro processing unit to in an off state, disconnects the first electrode and the second electrode, and the measuring circuit module applies a direct-current signal to the first electrode and the second electrode of the humidity-sensitive module, to measure a humidity-sensitive resistance value of the humidity-sensitive module, where in this case, C1 and C2 are equivalent to a circuit breaker, and do not exert any influence on measurement of the humidity-sensitive resistance value.
[0073] The resonant frequency and the humidity-sensitive resistance value vary with a water content of the humidity-sensitive material.
[0074] The measuring circuit module transmits the resonant frequency and the humidity-sensitive resistance value of the humidity-sensitive module that are measured to the micro processing unit.
[0075] The micro processing unit calculates two ambient air humidity reference values, namely, an ambient air humidity reference value a and an ambient air humidity reference value b, respectively according to the resonant frequency and the humidity-sensitive resistance value.
[0076] Preferably, a root mean square value or a mean value of the ambient air humidity reference value a and the ambient air humidity reference value b is output as a result.
[0077] In some implementations, the humidity sensor chip performs self-diagnosis and replacement prompting, where specifically, the micro processing unit includes a determining function module, where the determining function module implements a determining function as follows: the determining function module in the micro processing unit performs self-diagnosis according to the ambient air humidity reference value a and the ambient air humidity reference value b that are obtained through calculation to determine whether the humidity sensor chip has a fault or aged performance, which is specifically implemented as follows: presetting a first determining threshold, and calculating an absolute value of a difference between the ambient air humidity reference value a and the ambient air humidity reference value b; determining whether the absolute value of the difference between the ambient air humidity reference value a and the ambient air humidity reference value b is greater than the first determining threshold; if the absolute value of the difference is less than the first determining threshold, outputting the root mean square value or mean value of the ambient air humidity reference value a and the ambient air humidity reference value b as a result, and indicating that the humidity sensor chip works normally; if the absolute value of the difference is equal to or greater than the first determining threshold, further outputting, by the micro processing unit, alarm information, where the alarm information indicates that the humidity sensor chip has a fault or aged performance, and prompts that maintenance or replacement is needed; preferably, further presetting, by the determining function module in the micro processing unit, a second determining threshold, where the second determining threshold is greater than the first determining threshold; if the absolute value of the difference is less than the first determining threshold, outputting the root mean square value or mean value of the ambient air humidity reference value a and the ambient air humidity reference value b as a result, and indicating that the humidity sensor chip works normally; if the absolute value of the difference is equal to or greater than the first determining threshold and less than the second determining threshold, outputting, by the micro processing unit, alarm information, where the alarm information indicates that the humidity sensor chip might have a fault or has slightly aged performance, and recommends maintenance or replacement; and if the absolute value of the difference is equal to or greater than the second determining threshold, outputting, by the micro processing unit, error information, where the error information indicates that the humidity sensor chip has a fault or has severely aged performance, and must be maintained or replaced.
[0078] In an example, the first determining threshold is preset to 1% RH, and the second determining threshold is preset to 2% RH. In a specific measurement, if the micro processing
unit obtains through calculation that the ambient air humidity reference value a is 23.27% RH
according to a standard curve of a physical property A of the humidity-sensitive module varying
with the water content, and that the ambient air humidity reference value b is 24.11%RH
according to a standard curve of a physical property B of the humidity-sensitive module varying
with the water content, an absolute value of the difference between the ambient air humidity
reference value a and the ambient air humidity reference value b is 24.11% RH - 23.27% RH=
0.84% RH.
[0079] Through comparison, the determining function module in the micro processing unit arrives at that the absolute value 0.84% RH of the difference is less than the first determining
threshold, 1% RH, therefore, indicates that the humidity sensor chip works normally, and
outputs an ambient air humidity value by using a root mean square value, 23.69% RH, of a and
b as a final result.
[0080] In an example, the first determining threshold is preset to 1% RH, and the second
determining threshold is preset to 2% RH. In a specific measurement, if the micro processing
unit obtains through calculation that the ambient air humidity reference value a is 42.69% RH
according to a standard curve of a physical property A of the humidity-sensitive module varying
with the water content, and that the ambient air humidity reference value b is 44.57%RH
according to a standard curve of a physical property B of the humidity-sensitive module varying
with the water content, an absolute value of the difference between the ambient air humidity
reference value a and the ambient air humidity reference value b is 44.57% RH - 42.69% RH =
1.88% RH. Through comparison, the determining function module in the micro processing unit
arrives at that the absolute value of the difference 1.88% RH is greater than the first
determining threshold, 1% RH, but is less than the second determining threshold, 2% RH.
Therefore, the micro processing unit outputs alarm information, where the alarm information
indicates that the humidity sensor chip might have a fault or has slightly aged performance and
recommends maintenance or replacement.
[0081] In another example, the first determining threshold is preset to 0.5% RH, and the
second determining threshold is preset to 1% RH. In a specific measurement, if the micro processing unit obtains through calculation that the ambient air humidity reference value a is 42.69% RH according to a standard curve of a physical property A of the humidity-sensitive module varying with the water content, and that the ambient air humidity reference value b is 44.57%RH according to a standard curve of a physical property B of the humidity-sensitive module varying with the water content, an absolute value of the difference between the ambient air humidity reference value a and the ambient air humidity reference value b is 44.57% RH
42.69% RH = 1.88% RH. Through comparison, the determining function module in the micro
processing unit arrives at that the absolute value of the difference 1.88% RH is greater than the second determining threshold, 1% RH. Therefore, the micro processing unit outputs error information, where the error information indicates that the humidity sensor chip may have a fault or have severely aged performance and must be maintained or replaced.
[0082] It can be known from the foregoing three examples that whether the micro processing unit outputs alarm information or error information or prompts normal working and outputs a final calculation result depends on magnitudes of the preset first determining threshold and the preset second determining threshold.
[0083] Moreover, setting of magnitudes of the first determining threshold and the second determining threshold depends tolerance of an end user for performance degradation of the humidity sensor chip. If the end user has relatively low tolerance for performance degradation of the humidity sensor chip, and there is a requirement for accurate measurement, the first determining threshold and the second determining threshold may be preset to be relatively small. Otherwise, if the end user has relatively high tolerance for performance degradation of the humidity sensor chip, and there is no requirement for particularly accurate measurement, the first determining threshold and the second determining threshold may be preset to be relatively large. On the other hand, magnitudes of the preset first determining threshold and the preset second determining threshold also affect an in-service time of the humidity sensor chip. If the first determining threshold and the second determining threshold are preset to be relatively small, the in-service time of the humidity sensor chip is relatively short. If the first determining threshold and the second determining threshold are preset to be relatively large, the in-service time of the humidity sensor chip is relatively long. The above completely depends on requirements of the end user on accuracy and use costs.
[0084] In the various implementations described in the specification, the technical means adopted are not contradictory, that is, the technical means can be freely combined to construct different technical solutions. The possible technical solutions obtained through arrangement and combination are all deemed to have been recorded in the original application documents of this application. Unless specially stated, some technical means are technically contradictory and cannot coexist in the same technical solution. The descriptions above are merely specific preferred implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any change or replacement that can be easily conceived of by a person skilled in the art within the scope of the technology disclosed by the present invention shall fall within the protection scope of the present invention.
[0085] It will be understood that the term "comprise" and any of its derivatives (eg comprises, comprising) as used in this specification is to be taken to be inclusive of features to which it refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.
[0086] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.
Claims (9)
1. A humidity sensor chip having a three-electrode structure, comprising: a
humidity-sensitive module, a measuring circuit module, and a micro processing unit, wherein
the humidity-sensitive module comprises a humidity-sensitive material (4), a substrate (5),
a first electrode (1), a second electrode (2), and a third electrode (3); the humidity-sensitive
material (4), the substrate (5), the first electrode (1), the second electrode (2), and the third
electrode (3) constitute a humidity-sensitive capacitor-resistor composite structure having a
three-electrode structure;
a humidity-sensitive resistor is constituted between the first electrode (1) and the second
electrode (2), a humidity-sensitive capacitor is constituted between the first electrode (1) and
the third electrode (3), a humidity-sensitive capacitor is also constituted between the second
electrode (2) and the third electrode (3), and there is a same humidity-sensitive material
between every two of the first electrode (1), the second electrode (2), and the third electrode
(3); the humidity-sensitive material (4) is prepared on a front face of the substrate (5), the first
electrode (1) and the second electrode (2) are both located on an upper face of the
humidity-sensitive material (4), and the third electrode (3) is located on a back face of the
substrate (5); the first electrode (1) and the second electrode (2) are a pair of electrodes
surrounding each other without being in contact with each other and having the
humidity-sensitive material (4) therebetween;
the first electrode (1), the humidity-sensitive material (4), the substrate (5), and the third
electrode (3) constitute a capacitor structure, and the humidity-sensitive material (4) and the
substrate (5) are a composite dielectric layer of the capacitor; the second electrode (2), the
humidity-sensitive material (4), the substrate (5), and the third electrode (3) also constitute a
capacitor structure, and the humidity-sensitive material (4) and the substrate (5) are a dielectric
layer of the capacitor; the first electrode (1), the humidity-sensitive material (4), and the second
electrode (2) constitute a humidity-sensitive resistor structure, and the humidity-sensitive
material serves as a humidity-sensitive material of the humidity-sensitive resistor; and the substrate is a crystalline material having a piezoelectric effect; wherein the humidity-sensitive material (4) is an even mixture formed by adding 5 to 8% by weight of cuprous oxide, 4 to 7% by weight of zinc oxide, and 4 to 8% by weight of
4-epoxypropanoxycarbazole into phenyl benzoate.
2. The humidity sensor chip according to claim 1, wherein the humidity-sensitive module,
the measuring circuit module, and the micro processing unit are integrated on a substrate
material by using a package on package technology, to obtain the humidity sensor chip;
preferably, the first electrode (1) and the second electrode (2) are a pair of interdigital
electrodes, a pair of spiral electrodes, or a pair of swiss-roll electrodes;
preferably, the first electrode (1), the second electrode (2), and the third electrode (3) are
gold electrodes or silver electrodes;
preferably, the first electrode (1), the second electrode (2), and the third electrode (3) are
all prepared by using an evaporation process, a sputtering process, or a radio-frequency
magnetron sputtering process;
preferably, the humidity-sensitive material (4) is an organic material, an inorganic material,
or an organic-inorganic composite material;
preferably, the humidity-sensitive material (4) is a hydrophobic material;
preferably, the substrate (5) is made from quartz flakes;
preferably, an electronic switch controlled by the micro processing unit is disposed
between the first electrode (1) and the second electrode (2), when a resonant frequency of the
humidity-sensitive module is measured, the electronic switch is controlled by the micro
processing unit to be in an on state, to short-circuit the first electrode (1) and the second
electrode (2), and the electronic switch keeps an off state in the remaining time;
preferably, the electronic switch is a transmission gate made up of a pair of transistors, that
is, a PMOS and an NMOS; a control end of the transmission gate is connected to the micro
processing unit; and
preferably, a temperature sensor is further integrated in the humidity-sensitive module, the
temperature sensor is connected to the measuring circuit module, the measuring circuit module
transmits a measured temperature value of the humidity-sensitive material to the micro
processing unit, and the micro processing unit corrects a measured ambient air humidity value according to the temperature value.
3. The humidity sensor chip according to claim 2, wherein:
the measuring circuit module is configured to perform the following two measurement operations during measurement, wherein a sequence of the two measurement operations is not limited: (1) applying, by the measuring circuit module, an alternating-current excitation signal having a variable frequency within a preset frequency range to the first electrode (1) and the third electrode (3) of the humidity-sensitive module, to measure a resonant frequency of the humidity-sensitive module; or applying, by the measuring circuit module, an alternating-current excitation signal having a variable frequency within a preset frequency range to the second electrode (2) and the third electrode (3) of the humidity-sensitive module, to measure a resonant frequency of the humidity-sensitive module, wherein in the step of this measuring operation, the electronic switch is controlled by the micro processing unit to be in an on state, to short-circuit the first electrode (1) and the second electrode (2), and the measuring circuit module applies the alternating-current excitation signal having the variable frequency within the preset frequency range to the first electrode (1), the second electrode (2), and the third electrode (3) of the humidity-sensitive module, to measure the resonant frequency of the humidity-sensitive module; and (2) disconnecting, by the electronic switch as being controlled by the micro processing unit to in an off state, the first electrode (1) and the second electrode (2), and applying, by the measuring circuit module, a direct-current signal to the first electrode (1) and the second electrode (2) of the humidity-sensitive module, to measure a humidity-sensitive resistance value of the humidity-sensitive module, wherein the resonant frequency and the humidity-sensitive resistance value vary with a water content of the humidity-sensitive material; the measuring circuit module transmits the resonant frequency and the humidity-sensitive resistance value of the humidity-sensitive module that are measured to the micro processing unit; and the micro processing unit calculates two ambient air humidity reference values, namely, an ambient air humidity reference value a and an ambient air humidity reference value b, respectively according to the resonant frequency and the humidity-sensitive resistance value; and a root mean square value or a mean value of the ambient air humidity reference value a and the ambient air humidity reference value b is output as a result.
4. The humidity sensor chip according to claim 2, wherein: the micro processing unit calculates the two ambient air humidity reference values, namely, the ambient air humidity reference value a and the ambient air humidity reference value b, respectively from the resonant frequency and the humidity-sensitive resistance value according to a preset formula.
5. The humidity sensor chip according to claim 2, further comprising a storage module, wherein the storage module stores a standard parameter library, and the standard parameter library records both standard curves of the resonant frequency and the humidity-sensitive resistance value of the humidity-sensitive module that vary with a water content of the humidity-sensitive material; and the micro processing unit performs, according to the resonant frequency and the humidity-sensitive resistance value of the humidity-sensitive module that are measured, indexing, comparison, and calculation respectively on the standard curves of the resonant frequency and the humidity-sensitive resistance value of the humidity-sensitive module that vary with the water content of the humidity-sensitive material and that are recorded in the standard parameter library, to obtain the ambient air humidity reference value a and the ambient air humidity reference value b respectively.
6. The humidity sensor chip according to claim 4 or 5, wherein: the humidity sensor chip performs self-diagnosis and replacement prompting, wherein specifically: the micro processing unit comprises a determining function module, wherein the determining function module implements a determining function as follows: the determining function module in the micro processing unit performs self-diagnosis according to the ambient air humidity reference value a and the ambient air humidity reference value b that are obtained through calculation to determine whether the humidity sensor chip has a fault or aged performance, which is specifically implemented as follows: presetting a first determining threshold, and calculating an absolute value of a difference between the ambient air humidity reference value a and the ambient air humidity reference value b; determining whether the absolute value of the difference between the ambient air humidity reference value a and the ambient air humidity reference value b is greater than the first determining threshold; if the absolute value of the difference is less than thefirst determining threshold, outputting the root mean square value or mean value of the ambient air humidity reference value a and the ambient air humidity reference value b as a result, and indicating that the humidity sensor chip works normally; if the absolute value of the difference is equal to or greater than thefirst determining threshold, further outputting, by the micro processing unit, alarm information, wherein the alarm information indicates that the humidity sensor chip has a fault or aged performance, and prompts that maintenance or replacement is needed; further presetting, by the determining function module in the micro processing unit, a second determining threshold, wherein the second determining threshold is greater than the first determining threshold; if the absolute value of the difference is less than thefirst determining threshold, outputting the root mean square value or mean value of the ambient air humidity reference value a and the ambient air humidity reference value b as a result, and indicating that the humidity sensor chip works normally; if the absolute value of the difference is equal to or greater than thefirst determining threshold and less than the second determining threshold, outputting, by the micro processing unit, alarm information, wherein the alarm information indicates that the humidity sensor chip might have a fault or has slightly aged performance, and recommends maintenance or replacement; and if the absolute value of the difference is equal to or greater than the second determining threshold, outputting, by the micro processing unit, error information, wherein the error information indicates that the humidity sensor chip has a fault or has severely aged performance, and must be maintained or replaced.
7. The humidity sensor chip according to claim 1, wherein:
a precursor solution of the humidity-sensitive material is a hydrophobic oily mixture
comprising cuprous oxide, zinc oxide, 4-epoxypropanoxycarbazole (CAS number: 53-95-2),
and phenyl benzoate;
cuprous oxide is granular cuprous oxide having a size of 1 to 10 m, and zinc oxide is
rod-shaped zinc oxide having a size of 0.5 to 5 m; and
a weight part of cuprous oxide is from 5 to 8%, a weight part of zinc oxide is from 4 to
7%, a weight part of 4-epoxypropanoxycarbazole is from 3 to 6%, and the remaining part is
phenyl benzoate.
8. A method for preparing the humidity sensor chip according to claim 1, wherein
the method for preparing the humidity-sensitive module comprises the following steps:
(a) preparing a precursor solution of the humidity-sensitive material (4): adding 5 to 8% by
weight of cuprous oxide, 4 to 7% by weight of zinc oxide, and 4 to 8% by weight of
4-epoxypropanoxycarbazole into phenyl benzoate; and heating the mixture to 90 to 110°C, and
performing vigorous stirring for 30 to 60 minutes by using a magnetic stirrer to form a
hydrophobic oily mixture;
(b) preparing the humidity-sensitive material (4) on a front face of a substrate: spin-coating
the hydrophobic oily mixture obtained in step (a) on the front face of the substrate (5) at 90 to
110°C, and then naturally cooling to room temperature;
(c) preparing a third electrode (3) on a back face of the substrate (5) by using an
evaporation process, a sputtering process, or a radio-frequency magnetron sputtering process;
and
(d) preparing, by using a mask, a first electrode (1) and a second electrode (2) the front
face of the substrate by using an evaporation process, a sputtering process, or a radio-frequency
magnetron sputtering process.
9. A method for preparing the humidity sensor chip according to claim 8, wherein step (c)
is adjusted to be before step (a).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010011995.7A CN112229878B (en) | 2020-01-07 | 2020-01-07 | Humidity sensor chip with three-electrode structure |
| CN202010011995.7 | 2020-01-07 | ||
| PCT/CN2020/115945 WO2021139206A1 (en) | 2020-01-07 | 2020-09-17 | Humidity sensor chip having three-electrode structure |
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| US3926858A (en) * | 1973-07-13 | 1975-12-16 | Tokyo Shibaura Electric Co | Moisture sensitive element |
| US4086556A (en) * | 1975-09-18 | 1978-04-25 | Matsushita Electric Industrial Co., Ltd. | Humidity sensitive ceramic resistor |
| US4793182A (en) * | 1987-06-02 | 1988-12-27 | Djorup Robert Sonny | Constant temperature hygrometer |
| CN104391015A (en) * | 2014-12-03 | 2015-03-04 | 东南大学 | Capacitive humidity sensor of integrated ultrasonic structure and preparation method of capacitive humidity sensor of integrated ultrasonic structure |
-
2020
- 2020-09-17 AU AU2020256373A patent/AU2020256373B2/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3926858A (en) * | 1973-07-13 | 1975-12-16 | Tokyo Shibaura Electric Co | Moisture sensitive element |
| US4086556A (en) * | 1975-09-18 | 1978-04-25 | Matsushita Electric Industrial Co., Ltd. | Humidity sensitive ceramic resistor |
| US4793182A (en) * | 1987-06-02 | 1988-12-27 | Djorup Robert Sonny | Constant temperature hygrometer |
| CN104391015A (en) * | 2014-12-03 | 2015-03-04 | 东南大学 | Capacitive humidity sensor of integrated ultrasonic structure and preparation method of capacitive humidity sensor of integrated ultrasonic structure |
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