CN113125523B - Humidity sensor based on PAAm flexible hydrogel and preparation method thereof - Google Patents
Humidity sensor based on PAAm flexible hydrogel and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a humidity sensor based on PAAm flexible hydrogel and a preparation method thereof, wherein the humidity sensor based on PAAm flexible hydrogel comprises a flexible circuit layer and polyacrylamide organic hydrogel; and the polyacrylamide organic hydrogel is coated on the flexible circuit board and forms a polyacrylamide organic hydrogel film. The sensitivity of the humidity sensor reaches 6.29 between 12% and 85% of relative humidity and reaches 149.9 between 85% and 95% of relative humidity; the humidity sensor has good stability in temperature (31-42 ℃), bending (radius of curvature is infinite to 6.81 mm), pressure (0-8N) and ten days of continuous measurement. The present invention utilizes the excellent flexibility, high transparency and excellent mechanical strength of the organic hydrogel, and in addition, its excellent water-retaining property allows the sensor to have high flexibility and mechanical stability after being left for 24 hours in a very low humidity environment (12% relative humidity) without dehydration.
Description
Technical Field
The invention relates to the technical field of humidity sensors, in particular to a humidity sensor based on PAAm flexible hydrogel and a preparation method thereof.
Background
With the development of artificial intelligence, the demands of related industry chains for flexible electronic devices are also increasing. Flexible electronics have attracted considerable attention in many areas, including emerging health monitoring, artificial electronics skin and the robotic industry. Among these most advanced electronic products, humidity sensors are attracting attention due to their high accuracy, fast response time, good repeatability and ease of manufacture. To meet these demands, a number of researchers have studied humidity sensors based on various sensing principles. These sensors include resistive, capacitive, and optical principles. As the most common method, resistive sensing devices typically rely on changing the resistivity of the moisture sensitive material. For example, zhao et al developed a flexible molybdenum disulfide-based humidity sensor that can reversibly absorb/desorb water molecules through a single layer of molybdenum disulfide film. The varying ambient humidity effectively adjusts the charge density of the molybdenum disulfide film, thereby changing the resistance of the overall device. In contrast to resistive humidity sensing techniques, the output parameter of capacitive humidity sensing is typically dependent on the dielectric constant as a function of humidity. The humidity sensing technology based on the capacitor has the advantages of high sensitivity, low power consumption, no influence of temperature and the like, and another trend of the development of the humidity sensor is led.
Materials that make related humidity sensitive structures, in addition to inorganic humidity sensitive materials, organic polymers such as hydrogels, are also good candidates for developing wearable humidity sensing electronics. However, few reports have been made on the use of organic hydrogels for the fabrication of humidity sensors. The hydrogel matrix is a three-dimensional network composed of a plurality of polymer chains, and hydrophilic groups in the three-dimensional network are mostly hydroxyl groups, amino groups or carboxyl groups. These groups readily absorb water molecules and form hydrogen bonds with water molecules, thereby changing electrical parameters such as dielectric constant, resistivity or Refractive Index (RI). However, conventional hydrogels are easily dehydrated at ambient temperature or in extreme environments (high temperature and low humidity, low temperature and low humidity, etc.), and the mechanical properties of the dehydrated hydrogels are extremely poor (bending and stretching are impossible), and such dehydration phenomenon seriously hinders their application.
Disclosure of Invention
The invention aims to solve the technical problem of providing a humidity sensor based on PAAm flexible hydrogel, which has the advantages of excellent flexibility, high transparency, excellent mechanical strength and good stability.
In order to solve the above problems, the present invention provides a PAAm flexible hydrogel-based humidity sensor, comprising:
a flexible circuit layer;
and the polyacrylamide organic hydrogel is coated on the flexible circuit board and forms a polyacrylamide organic hydrogel film.
As a further improvement of the present invention, the polyacrylamide organic hydrogel is synthesized in the presence of water and an alcohol binary solvent.
As a further improvement of the present invention, the alcohol includes ethylene glycol and glycerol.
As a further improvement of the present invention, the flexible circuit layer includes a flexible substrate and interdigital electrodes prepared on the flexible substrate.
As a further improvement of the present invention, the flexible substrate is a polyimide film.
As a further improvement of the invention, the interdigital electrode is prepared on the flexible substrate by a standard screen printing method and a wet etching process with single-sided copper coating.
The invention also provides a preparation method of the humidity sensor based on the PAAm flexible hydrogel, which comprises the following steps:
covering the flexible circuit layer on the bottom plate;
coating a patterning mask on the flexible circuit layer;
covering a top plate on the patterned mask, wherein the top plate, the patterned mask and the flexible circuit layer are matched to form a cavity;
filling polyacrylamide organic hydrogel solution into the cavity;
heating and polymerizing the polyacrylamide organic hydrogel solution to form a polyacrylamide organic hydrogel film;
and removing the top plate, the patterned mask and the bottom plate.
As a further improvement of the present invention, the heating polymerization of the polyacrylamide organic hydrogel solution comprises: and heating the polyacrylamide organic hydrogel in a water bath kettle to polymerize.
As a further improvement of the invention, the patterned mask is made of double faced adhesive tape by laser engraving.
As a further improvement of the invention, the top and bottom plates are glass sheets.
The invention has the beneficial effects that:
the invention develops the flexible hydrogel humidity sensor based on PAAm by utilizing the hydrogel material with high transparency and high flexibility, so that the sensitivity of the humidity sensor reaches 6.29 between 12 percent and 85 percent of relative humidity and reaches 149.9 between 85 percent and 95 percent of relative humidity; the humidity sensor has good stability in temperature (31-42 ℃), bending (radius of curvature is infinite to 6.81 mm), pressure (0-8N) and ten days of continuous measurement.
According to the invention, the excellent flexibility, high transparency and excellent mechanical strength of the organic hydrogel are utilized, and hydrophilic groups in the hydrogel polymer network are bonded with water molecules in a hydrogen bond mode when the relative humidity is increased, so that the dielectric constant of the PAAm organic hydrogel film is changed, and the total capacitance of the sensor is changed. In addition, its excellent water retention properties allow the sensor to remain highly flexible and mechanically stable after 24 hours in a very low humidity environment (12% relative humidity) without dehydration.
The sensor has successfully detected dynamic humidity changes of human breath and tiny humidity changes of human skin and blade surfaces.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention, as well as the preferred embodiments thereof, together with the following detailed description of the invention, given by way of illustration only, together with the accompanying drawings.
Drawings
FIG. 1 is a flow chart of a method of making a PAAm flexible hydrogel based humidity sensor in accordance with a preferred embodiment of the present invention;
FIG. 2 is a schematic diagram of the humidity sensing principle of the PAAm flexible hydrogel-based humidity sensor in the preferred embodiment of the present invention;
FIG. 3 is a graph of mass change under test of the water absorption capacity of a humidity sensor based on PAAm flexible hydrogels in accordance with a preferred embodiment of the present invention;
FIG. 4 is an experiment of lap shear strength of a humidity sensor based on PAAm flexible hydrogel in a preferred embodiment of the present invention; (a) The three humidity sensors with glycerol ratios are in a form at normal temperature, wherein PAAm-0% hydrogel is separated from the flexible circuit layer; (b) lap shear experimental block diagrams; (c) lap shear experimental plots; (d) Three hydrogels with different glycerol ratios have different stress-strain curves; (e) Distribution of maximum stress values of hydrogels of three glycerol ratios;
FIG. 5 is a dynamic humidity experiment of a humidity sensor based on PAAm flexible hydrogel in a preferred embodiment of the present invention; (a) a dynamic humidity experimental schematic, (b) humidity cycling at 60% -90% relative humidity, (c) amplifying one cycle in (b) comparing recovery times of the two sensors, (d) capacitance response changes of the organic hydrogel humidity sensors with two thicknesses of 50 μm and 125 μm under periodic changes of humidity, (e) definition of response/recovery rate, (f) distribution map of response and recovery rate of the flexible hydrogel humidity sensors with thicknesses of 50 μm and 125 μm;
FIG. 6 is a mirror humidity experiment of a humidity sensor based on PAAm flexible hydrogels in a preferred embodiment of the present invention; (a) a static humidity experimental schematic, (b) a static humidity response of a PAAm based flexible hydrogel humidity sensor, (c) a temperature effect of the sensor, (d) a bending effect of the sensor, (e) a pressure effect of the sensor, (f) a persistence test of the sensor;
FIG. 7 is a schematic illustration of a method of making a PAAm flexible hydrogel based humidity sensor in accordance with a preferred embodiment of the present invention; (a) double-sided adhesive, (b) double-sided adhesive mask after laser engraving, (c) attaching the mask to the flexible circuit layer (PI film and interdigital electrode), (d) covering the mask with a glass sheet to form a chamber, (e) filling the chamber with a precursor solution and heating at 60 ℃ for 24 hours, (f) removing the supported glass sheet and mask to form the PAAm-based flexible hydrogel humidity sensor.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
The humidity sensor based on the PAAm flexible hydrogel in the preferred embodiment of the invention comprises: the flexible circuit board comprises a flexible circuit layer and polyacrylamide organic hydrogel, wherein the polyacrylamide organic hydrogel is coated on the flexible circuit board and forms a polyacrylamide organic hydrogel film.
Optionally, the polyacrylamide organic hydrogel is synthesized in the presence of water and an alcohol binary solvent. Alternatively, the alcohols include ethylene glycol, glycerol, and the like.
In some embodiments, the flexible circuit layer includes a flexible substrate and interdigitated electrodes prepared on the flexible substrate. Optionally, the flexible substrate is a polyimide film. Alternatively, the interdigital electrode is prepared on the flexible substrate by single-sided copper coating through a standard screen printing method and a wet etching process.
As shown in fig. 1, the preferred embodiment of the present invention also discloses a method for preparing a humidity sensor based on PAAm flexible hydrogel, which comprises the following steps:
s10, covering the flexible circuit layer on the bottom plate.
S20, covering the patterning mask on the flexible circuit layer. Optionally, the patterned mask is made of double faced adhesive tape through laser engraving.
S30, covering the top plate on the patterned mask, wherein the top plate, the patterned mask and the flexible circuit layer are matched to form a cavity.
And S40, filling the polyacrylamide organic hydrogel solution into the cavity.
And S50, heating and polymerizing the polyacrylamide organic hydrogel solution to form a polyacrylamide organic hydrogel film. Optionally, the heating polymerization of the polyacrylamide organic hydrogel solution in step S50 includes: and heating the polyacrylamide organic hydrogel in a water bath kettle to polymerize.
S60, removing the top plate, the patterned mask and the bottom plate.
Optionally, the top plate and the bottom plate are glass sheets.
The invention develops the flexible hydrogel humidity sensor based on PAAm by utilizing the hydrogel material with high transparency and high flexibility, so that the sensitivity of the humidity sensor reaches 6.29 between 12 percent and 85 percent of relative humidity and reaches 149.9 between 85 percent and 95 percent of relative humidity; the humidity sensor has good stability in temperature (31-42 ℃), bending (radius of curvature is infinite to 6.81 mm), pressure (0-8N) and ten days of continuous measurement.
According to the invention, the excellent flexibility, high transparency and excellent mechanical strength of the organic hydrogel are utilized, and hydrophilic groups in the hydrogel polymer network are bonded with water molecules in a hydrogen bond mode when the relative humidity is increased, so that the dielectric constant of the PAAm organic hydrogel film is changed, and the total capacitance of the sensor is changed. In addition, its excellent water retention properties allow the sensor to remain highly flexible and mechanically stable after 24 hours in a very low humidity environment (12% relative humidity) without dehydration.
The sensor has successfully detected dynamic humidity changes of human breath and tiny humidity changes of human skin and blade surfaces.
The working principle of the humidity sensor based on the PAAm flexible hydrogel is as follows:
fig. 2 illustrates the principle of operation of the humidity sensor in a molecular polymerization diagram. Acrylamide, a cross-linking agent N' -methylene bisacrylamide and an initiator ammonium persulfate are polymerized under the action of binary solvents (pure water DI and glycerol Gly) to form PAAm hydrogel. Wherein the amino group in the PAAm polymer chain and the hydroxyl group in Gly are bonded in a hydrogen bond mode to form a whole three-dimensional organic polymer gel network. The hydrogel network has amino and hydroxyl hydrophilic groups, and the hydrophilic groups can bond with water molecules in a hydrogen bond mode. During the contact with water molecules, the hydrogel swells, changing the dielectric constant of the organic polymer, and thus changing the capacitance value of the humidity sensor.
The invention relates to a water absorption capacity test of a humidity sensor based on PAAm flexible hydrogel, which comprises the following steps:
in the experiments, PAAm organic hydrogel (6×10×1mm 3 ) Placing the PAAm hydrogel at 25 ℃ and 60% RH for 24 hours to enable the PAAm hydrogel to reach a stable state under fixed temperature and humidity,so as to remove the influence of the environmental temperature and humidity fluctuation process on the environmental temperature and humidity fluctuation process. After 24 hours, the PAAm hydrogel was transferred to a humid environment (temperature 25 ℃) of 95% rh for 2 hours. The mass of the sample was recorded every 30 minutes during the experiment for 2 hours, and the mass change is shown in fig. 3. For ease of description, PAAm-X was described as the hydrogel component in subsequent experiments. Wherein X is the proportion of glycerol to the total volume of glycerol and water. PAAm-0% and PAAm-16% have reached a stable value at half an hour of measurement, whereas PAAm-32% hydrogels have been continuously absorbing water during the two hour measurement.
The lap shear strength test of the humidity sensor based on PAAm flexible hydrogel comprises the following steps:
in order to obtain stable sensing performance, the PAAm organic hydrogel film must firmly adhere to the electrode layer. The peel strength of the organic hydrogels was quantitatively measured by lap shear strength. In the experiment, a PAAm organic hydrogel film of thickness 1mm was sandwiched between two flexible electrode layers. As the tensile strain increases, the organic hydrogel elastically deforms, during which the stress increases linearly. When the stress reaches a level where the adhesion is not maintained, the organic hydrogel begins to detach from the substrate, and the stress rapidly decreases. As shown in FIG. 4, the maximum adhesive strength was 0.62kPa, 3.02kPa and 5.48kPa for PAAm-0% hydrogel, PAAm-16% and PAAm32% organic hydrogel, respectively. The results show that the more Gly in the PAAm organic hydrogel film, the more viscous the organic hydrogel to the substrate.
The invention is based on the dynamic humidity test of the humidity sensor of PAAm flexible hydrogel, so as to determine the synchronism of the humidity sensor to the humidity, the response and the recovery rate:
to determine the synchronicity of the dynamic response of the PAAm microgel humidity sensor and its response/recovery time, the present invention performed a series of dynamic tests on the sensor as shown in fig. 5. Wherein the humidity environment was alternated between-60% and-90% humidity level by controlling humidification 36s and dehumidification 54s, a continuous change curve of PAAm flexible hydrogel humidity sensor capacitance was measured (fig. 5 b). It can be seen that the pam-16% (red line) and pam-32% (black line) capacitance output completely follows the change in ambient humidity during humidification (grey part) and dehumidification (white part).
As shown in FIG. 5 (c), the time taken for the PAAm-16% and PAAm-32% flexible hydrogel sensors to decrease to 90% of maximum was 20.71s and 46.39s, respectively. The data indicate that the greater the Gly duty cycle, the longer the sensor needs to be restored. In view of the short response/recovery times required in humidity sensor applications, PAAm-16% flexible hydrogel humidity sensor structures were chosen for response and recovery rate testing in the experiments. Next, a rapid dynamic test was performed on pam-16% flexible hydrogel humidity sensors of 50 μm and 125 μm thickness, whose capacitance output was plotted as a function of time as shown in fig. 5 (d). In the experiment, one cycle was selected from each of fig. 5 (d) for analysis of e-chart. Wherein a flexible hydrogel humidity sensor having a thickness of 125 μm requires a response time of 400ms at a capacitance increment of 1.1pF, and a flexible hydrogel humidity sensor having a thickness of 50 μm requires a response time of 300ms at a capacitance increment of 1 pF. By defining the response recovery rate κ as the ratio of the change in relative capacitance to time, it can be seen from FIG. 5 (e-f) that a 50 μm thick organic hydrogel sensor responds faster than a 125 μm thick sensor with the same change in capacitance. The response and recovery rate kappa of the 50 mu m thick flexible hydrogel humidity sensor are respectively between 4.14 and 5.19 and-4.23 and-2.87, and the response and recovery rate kappa of the 125 mu m thick flexible hydrogel humidity sensor are respectively between 1.93 and 2.60 and-1.60 and-1.01. Considering that a 50 μm thick PAAm-16% organic hydrogel sensor has better mechanical stability and rapid dynamic response, the flexible hydrogel humidity sensor of this Gly duty ratio (16%) and thickness (50 μm) was finally selected for a subsequent series of experiments.
The invention is based on the static humidity test of the humidity sensor of the PAAm flexible hydrogel, so as to determine the detection range, the repeatability and the influence degree of related factors:
the humidity response range and the sensitivity of the flexible hydrogel humidity sensor can be clarified by measuring the capacitance output of the flexible hydrogel humidity sensor under different static humidities, and experimental schematic diagrams and experimental data are shown in fig. 6. Wherein FIG. 6 (a) is a schematic diagram of a static humidity experiment, the humidity bottle meansA saturated salt solution for providing a specific relative humidity level. The saturated salt solution is LiBr, C 2 H 3 KO 2 、K 2 CO 3 NaBr, naCl, KCl and Na 2 HPO 4 . The relative humidity of the saturated salt solutions was 12%, 35%, 51%, 62%, 75%, 85% and 95%, respectively. In the static humidity test, the sensor was sealed in a humidity bottle for 2 hours during which time the hydrogel swelling of the humidity sensor was in dynamic equilibrium with the water vapor above the saturated saline solution of the humidity bottle. In each experiment, two identical sensors were tested.
The capacitive response output of the PAAm based flexible hydrogel humidity sensor between 12% and 95% relative humidity is shown in fig. 6 (b). Experimental data indicate that PAAm-16% flexible gel humidity sensors are capable of responding to a wide humidity range. The sensitivity σ is defined as formula 5-1:
as calculated from the data of fig. 6 (b), at relative humidity levels of 12% to 85%, the sensor sensitivity σ was 6.29, and when the relative humidity increased above 85%, the sensitivity σ increased sharply to 149.9. The capacitance in the control sample (control group in fig. 6 b) remained almost unchanged over the same humidity range.
Next, a series of temperature experiments were performed by controlled variable methods (constant humidity, temperature variation) to observe the capacitance output of the PAAm-based flexible hydrogel humidity sensor at different temperatures to define the effect of temperature on the humidity sensor. The data of fig. 6 (c) shows that the capacitance value of the PAAm-based hydrogel humidity sensor only varies by 2.6% in the temperature range of 31 to 42 ℃, and thus it can be considered that the PAAm-based hydrogel humidity sensor is hardly affected by temperature.
Because the substrate and the electrode of the sensor are flexible materials, relevant tests are carried out on bending conditions in the practical use process in the experiment. Fig. 6 (d) is the capacitive output of the sensor at three bending states at ambient temperature 25 c and relative humidity 65%. The sensor capacitance remained approximately 17.6pF with almost no change as the radius of curvature decreased from infinity to 6.81 mm. This shows that the PAAm flexible hydrogel based humidity sensor of the present invention can be well applied in applications where flexible bending is required.
As shown in FIG. 6 (e), the capacitance output of the PAAm flexible hydrogel humidity sensor of the present invention was maintained at 16.2pF during the 0-8N pressure application, indicating that the external pressure has little effect on the sensor. Therefore, the actions similar to the holding and pinching have little influence on the sensor in the actual use process.
In order to observe the stability of the PAAm based flexible hydrogel humidity sensor over a long period of time, the present invention also performed a 10 day test on the PAAm based flexible hydrogel humidity sensor, in which the capacitive response of the sensor at low relative humidity (12%) and medium relative humidity (51%) was recorded daily. Fig. 6 (f) shows that the PAAm hydrogel sensor of the present invention only reduced the capacitance output by 9.87% and 1.5%, respectively, under low and medium humidity conditions, indicating that the sensor has good long term stability.
As shown in fig. 7, in one embodiment, the preparation method of the PAAm-based flexible hydrogel humidity sensor of the present invention is as follows:
1. fabrication of flexible circuit layers
The flexible PI substrate and the interdigital electrode are collectively called a flexible circuit layer. Wherein the flexible substrate refers to a Polyimide (PI) film 25 μm thick. The electrode layer is prepared on the PI film through a standard screen printing method and a wet etching process by single-sided copper coating. The interdigital electrode has an overall size of 10mm×10mm, in which the line width is 125 μm, the pitch is 291 μm, and the thickness is 12 μm.
2. Preparation of humidity sensitive layer precursor solution
First, a solution of 4mg/mL of N' -methylenebisacrylamide (BIS) and a solution of 0.1 mg/. Mu.L of Ammonium Persulfate (APS) were prepared. Sonication (mixing well) was performed by sequentially mixing 5.6mM acrylamide (AAm), 2.96mL pure water (DI), 0.76mL glycerol (Gly), and 1.02mL BIS aqueous solution. Finally, adding 2.88 mu LAPS aqueous solution, and uniformly mixing to complete the preparation of the precursor solution.
3. Fabrication of a sensor
The present invention uses desktop CO with a graphical user interface (e.g., coreldhead) 2 A pulsed laser engraving machine (VersaLaser, universal laser) engraves the double sided adhesive (467 MP and 4638 MP,3 m) (fig. 7 a-b) as a patterned mask. Wherein the thickness of the double faced adhesive tape of 467MP and 468MP models is 50 or 125 μm respectively. By stacking the bottom glass sheet, flexible circuit layer, patterned mask and top glass sheet (fig. 7 c-d), a cavity is formed above the flexible circuit layer with a height consistent with the thickness of the double sided tape of 50 μm or 125 μm. The chamber was filled with our pre-prepared precursor solution (fig. 7 e) and subjected to a heating treatment (water bath 60 ℃ for 24 hours). After 24 hours, a PAAm flexible hydrogel based humidity sensor was formed by removing the top and bottom glass sheets used as supports and patterning the mask (fig. 7 f).
The above embodiments are merely preferred embodiments for fully explaining the present invention, and the scope of the present invention is not limited thereto. Equivalent substitutions and modifications will occur to those skilled in the art based on the present invention, and are intended to be within the scope of the present invention. The protection scope of the invention is subject to the claims.
Claims (8)
1. The preparation method of the humidity sensor based on the PAAm flexible hydrogel is characterized in that the humidity sensor comprises the following steps:
a flexible circuit layer;
the polyacrylamide organic hydrogel is coated on the flexible circuit layer and forms a polyacrylamide organic hydrogel film;
the preparation method of the humidity sensor based on the PAAm flexible hydrogel comprises the following steps:
covering the flexible circuit layer on the bottom plate;
coating a patterning mask on the flexible circuit layer;
covering a top plate on the patterned mask, wherein the top plate, the patterned mask and the flexible circuit layer are matched to form a cavity;
filling a polyacrylamide organic hydrogel solution into the cavity, wherein the polyacrylamide organic hydrogel solution consists of an N '-methylene bisacrylamide solution, an ammonium persulfate solution, acrylamide, pure water, glycerol, a BIS aqueous solution and an APS aqueous solution, wherein 4mg/mL of the N' -methylene bisacrylamide solution and 0.1 mg/mu L of the ammonium persulfate solution are firstly required to be prepared, 5.6mM acrylamide, 2.96mL of pure water, 0.76mL of glycerol and 1.02mL of the BIS aqueous solution are sequentially mixed for ultrasonic oscillation treatment, and finally 2.88 mu LAPS aqueous solution is added for uniform mixing, so that the preparation of a precursor solution can be completed;
heating and polymerizing the polyacrylamide organic hydrogel solution to form a polyacrylamide organic hydrogel film;
removing the top plate, the patterned mask and the bottom plate;
the polyacrylamide organic hydrogel is synthesized in the presence of water and an alcohol binary solvent.
2. The method of preparing a PAAm flexible hydrogel based humidity sensor of claim 1 wherein the alcohols comprise ethylene glycol, glycerol.
3. The method of making a PAAm flexible hydrogel based humidity sensor of claim 1 wherein said flexible circuit layer comprises a flexible substrate and interdigitated electrodes fabricated on said flexible substrate.
4. The method of preparing a PAAm flexible hydrogel-based humidity sensor of claim 3 wherein the flexible substrate is a polyimide film.
5. The method of manufacturing a PAAm flexible hydrogel based humidity sensor of claim 3 wherein said interdigitated electrodes are manufactured on said flexible substrate by standard screen printing and wet etching processes with single sided copper coating.
6. The method for preparing a PAAm flexible hydrogel-based humidity sensor of claim 1, wherein the heating polymerization of the polyacrylamide organic hydrogel solution comprises: and heating the polyacrylamide organic hydrogel in a water bath kettle to polymerize.
7. The method for preparing a PAAm flexible hydrogel-based humidity sensor according to claim 1, wherein the patterned mask is a double sided tape engraved by laser.
8. The method of making a PAAm flexible hydrogel based humidity sensor of claim 1 wherein said top and bottom plates are glass sheets.
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Citations (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08159998A (en) * | 1994-12-07 | 1996-06-21 | Sato Keiryoki Seisakusho:Kk | Humidity sensing element |
| JP2001221764A (en) * | 2000-02-04 | 2001-08-17 | Tdk Corp | Humidity sensor element and its manufacturing method |
| CN1793880A (en) * | 2005-12-27 | 2006-06-28 | 上海大学 | Preparation method of humidity sensitive element humidity sensing membrane of humidity sensor |
| CN103234648A (en) * | 2013-03-29 | 2013-08-07 | 清华大学 | Polymer bi-material micro-beam and temperature sensitive structure |
| CN103364463A (en) * | 2013-06-20 | 2013-10-23 | 东南大学 | pH sensor based on reduced graphene oxide (RGO) and pH value detection method using same |
| WO2014169119A1 (en) * | 2013-04-10 | 2014-10-16 | President And Fellows Of Harvard College | Stretchable ionics for transparent sensors and actuators |
| CN107179336A (en) * | 2016-03-10 | 2017-09-19 | 中国科学院苏州纳米技术与纳米仿生研究所 | Can pasting type ionic flexible humidity sensor, its preparation method and application |
| CN108169295A (en) * | 2017-10-30 | 2018-06-15 | 上海幂方电子科技有限公司 | Flexible humidity sensor and preparation method thereof |
| CN109490380A (en) * | 2018-12-27 | 2019-03-19 | 中山大学 | Humidity sensor and its preparation method of application, equipment and humidity sensor |
| CN109613075A (en) * | 2019-01-07 | 2019-04-12 | 电子科技大学 | A kind of flexible humidity sensor and preparation method thereof based on fibroin |
| CN110190188A (en) * | 2019-05-23 | 2019-08-30 | 东北师范大学 | A kind of polymer semiconductor thin film preparation method and application |
| CN111024777A (en) * | 2019-12-25 | 2020-04-17 | 广州钰芯传感科技有限公司 | Sensor for modifying tin oxide, preparation method thereof and application of sensor in gas-sensitive detection of nitric oxide |
| CN112268939A (en) * | 2020-10-27 | 2021-01-26 | 东南大学 | Humidity sensor based on mechanical metamaterial structure |
| CN112300408A (en) * | 2020-10-26 | 2021-02-02 | 广州大学 | Flexible high-tensile temperature-sensitive and humidity-sensitive hydrogel and preparation method and application thereof |
| CN112326743A (en) * | 2020-11-05 | 2021-02-05 | 重庆医科大学 | C-SF-FA flexible conductive film based on silk fibroin, wearable wound monitoring sensor and preparation method of wearable wound monitoring sensor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012178071A2 (en) * | 2011-06-23 | 2012-12-27 | Brown University | Device and methods for temperature and humidity measurements using a nanocomposite film sensor |
| US10161895B2 (en) * | 2014-12-23 | 2018-12-25 | 3M Innovative Properties Company | Electronic moisture sensor |
-
2021
- 2021-04-19 CN CN202110418006.0A patent/CN113125523B/en active Active
Patent Citations (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08159998A (en) * | 1994-12-07 | 1996-06-21 | Sato Keiryoki Seisakusho:Kk | Humidity sensing element |
| JP2001221764A (en) * | 2000-02-04 | 2001-08-17 | Tdk Corp | Humidity sensor element and its manufacturing method |
| CN1793880A (en) * | 2005-12-27 | 2006-06-28 | 上海大学 | Preparation method of humidity sensitive element humidity sensing membrane of humidity sensor |
| CN103234648A (en) * | 2013-03-29 | 2013-08-07 | 清华大学 | Polymer bi-material micro-beam and temperature sensitive structure |
| WO2014169119A1 (en) * | 2013-04-10 | 2014-10-16 | President And Fellows Of Harvard College | Stretchable ionics for transparent sensors and actuators |
| CN103364463A (en) * | 2013-06-20 | 2013-10-23 | 东南大学 | pH sensor based on reduced graphene oxide (RGO) and pH value detection method using same |
| CN107179336A (en) * | 2016-03-10 | 2017-09-19 | 中国科学院苏州纳米技术与纳米仿生研究所 | Can pasting type ionic flexible humidity sensor, its preparation method and application |
| CN108169295A (en) * | 2017-10-30 | 2018-06-15 | 上海幂方电子科技有限公司 | Flexible humidity sensor and preparation method thereof |
| CN109490380A (en) * | 2018-12-27 | 2019-03-19 | 中山大学 | Humidity sensor and its preparation method of application, equipment and humidity sensor |
| CN109613075A (en) * | 2019-01-07 | 2019-04-12 | 电子科技大学 | A kind of flexible humidity sensor and preparation method thereof based on fibroin |
| CN110190188A (en) * | 2019-05-23 | 2019-08-30 | 东北师范大学 | A kind of polymer semiconductor thin film preparation method and application |
| CN111024777A (en) * | 2019-12-25 | 2020-04-17 | 广州钰芯传感科技有限公司 | Sensor for modifying tin oxide, preparation method thereof and application of sensor in gas-sensitive detection of nitric oxide |
| CN112300408A (en) * | 2020-10-26 | 2021-02-02 | 广州大学 | Flexible high-tensile temperature-sensitive and humidity-sensitive hydrogel and preparation method and application thereof |
| CN112268939A (en) * | 2020-10-27 | 2021-01-26 | 东南大学 | Humidity sensor based on mechanical metamaterial structure |
| CN112326743A (en) * | 2020-11-05 | 2021-02-05 | 重庆医科大学 | C-SF-FA flexible conductive film based on silk fibroin, wearable wound monitoring sensor and preparation method of wearable wound monitoring sensor |
Non-Patent Citations (1)
| Title |
|---|
| 基于导电水凝胶的可穿戴传感器的制备与应用;马迪;《CNKI硕士电子期刊》;20210215;第1页-24页 * |
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