CN115024698A - Flexible pressure sensor for monitoring pulse waves and preparation method thereof - Google Patents
Flexible pressure sensor for monitoring pulse waves and preparation method thereof Download PDFInfo
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- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
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Abstract
The invention relates to a flexible pressure sensor for monitoring pulse waves and a preparation method thereof, wherein a sensitive layer and an interdigital electrode are respectively prepared and then assembled to obtain the flexible pressure sensor for monitoring the pulse waves; the prepared flexible pressure sensor for monitoring the pulse wave comprises a sensitive layer and an interdigital electrode, wherein the two electrodes of the interdigital electrode are connected through a lead, and the sensitive layer is a polymer elastomer film with a rigid raised microstructure array on the surface; the rigid raised microstructure array is a raised microstructure array based on conductive metal; the highest sensitivity of the flexible pressure sensor is not lower than 9.5kPa ‑1 The response time is not higher than 30ms, and the lower limit of mechanical detection is not higher than 8 Pa. The rigid raised microstructure constructed on the surface of the flexible sensitive layer has no response delay to mechanical stimulation,The damping-free pressure sensor can be endowed with high sensitivity, high response speed and low detection lower limit performance; the preparation method is simple, low in production cost and suitable for large-scale industrial production.
Description
Technical Field
The invention belongs to the technical field of pressure sensors, and relates to a flexible pressure sensor for monitoring pulse waves and a preparation method thereof.
Background
The pulse wave of human body contains a lot of physiological signals, which can continuously reflect the regular change trend of the hemodynamic parameters such as human heart rate, blood oxygen, blood pressure, etc., so as to evaluate the cardiovascular performance. In the field of traditional Chinese medicine, pulse diagnosis is also one of important diagnosis modes, but pulse diagnosis is mainly based on the experience of traditional Chinese medicine to carry out subjective judgment, and the diagnosis result has great difference and is difficult to objectively quantify. The appearance of the pulse diagnosis instrument provides conditions for objective standardized diagnosis of traditional Chinese medicine, but the traditional pulse diagnosis instrument has large volume and cannot be used for real-time wearable monitoring and wide popularization and application. The flexible pressure sensor is adopted to collect and analyze the pulse wave signals of the human body, and the pulse wave signals are converted into digital signals for quantitative analysis, so that the device has important application prospect in the field of wearable and continuous monitoring of cardiovascular diseases. In order to realize high-quality monitoring of a weak signal of pulse wave, a raised microstructure is usually introduced into a flexible pressure sensor to improve the sensitivity of the sensor, but the traditional flexible sensor is composed of a flexible polymer elastomer from a substrate to the microstructure, and the flexible polymer material has viscoelasticity and has large damping property and hysteresis property on mechanical stimulation, so that the lower limit of mechanical detection of the flexible pressure sensor is high, the response speed is low, and high-resolution and high-quality monitoring of a characteristic peak contained in the pulse wave signal cannot be realized.
Therefore, the research on the high-sensitivity and quick-response flexible pressure sensor capable of monitoring the pulse wave signals and the preparation method thereof have very important significance.
Disclosure of Invention
The present invention is directed to solving the above-mentioned problems of the prior art and to providing a flexible pressure sensor for monitoring pulse waves and a method for manufacturing the same.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a flexible pressure sensor for monitoring pulse waves comprises a sensitive layer and an interdigital electrode, wherein the two electrodes of the interdigital electrode are connected through a lead, and the sensitive layer is a polymer elastomer film with a rigid protruding microstructure array on the surface;
the rigid raised microstructure array is a raised microstructure array based on conductive metal;
the maximum sensitivity of the flexible pressure sensor is not lower than 9.5kPa -1 The response time is not higher than 30ms, and the lower limit of mechanical detection is not higher than 8 Pa.
As a preferred technical scheme:
a flexible pressure sensor for monitoring pulse waves as described above, said conductive metal being gold, silver or copper.
The flexible pressure sensor for monitoring the pulse wave is characterized in that the thickness of the polymer elastomer film is 0.2-0.5 mm;
the metal thickness of the interdigital electrode is 100-200 nm; the length of the interdigital electrode is 10-20 mm, the width is 10-20 mm, and the finger width and the finger distance of the interdigital are 0.2-2.0 mm.
According to the flexible pressure sensor for monitoring the pulse wave, the shape of the bulges in the rigid bulge microstructure array is hemispherical, the diameter of the hemisphere is 0.1-1.0 mm (less than 0.1mm, the existing additive manufacturing technology is difficult to realize; if the diameter of the hemisphere is more than 1.0mm, the size of the bulge microstructure is too large to play a role in sensitization), and the distance between the centers of two adjacent hemispherical bulges is 0.15-1.5 mm.
The invention also provides a flexible pressure sensor for monitoring pulse waves, which is prepared by respectively preparing the sensitive layer and the interdigital electrode and assembling the sensitive layer and the interdigital electrode to obtain the flexible pressure sensor for monitoring the pulse waves;
the rigid raised microstructure array on the surface of the sensitive layer is prepared by an additive manufacturing technology; the microstructure in the prior art is mainly prepared indirectly by a template method, the microstructure can only be formed indirectly by using a flexible polymer material through reverse molding from a fixed template, the microstructure cannot be formed indirectly by using a rigid metal material through reverse molding from the template, and the additive manufacturing technology creates conditions for forming a convex microstructure by using the rigid metal material.
As a preferred technical scheme:
the method comprises the following specific preparation steps:
(1) uniformly coating a layer of polymer elastomer precursor solution or elastic polymer solution on a plane mould, putting the mould into an oven for complete curing, and removing the film to obtain a polymer elastomer film;
(2) constructing a conductive metal slurry-based raised microstructure array on the surface of the polymer elastomer film by an additive manufacturing technology, and heating and curing to form a conductive metal-based rigid raised microstructure array to prepare the sensitive layer;
(3) firstly, sequentially ultrasonically cleaning a polymer film in acetone, ethanol and deionized water, drying, then carrying out plasma treatment on the surface of the polymer film, then covering a mask plate with an interdigital structure on the polymer film, depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain the interdigital electrode;
(4) and (3) contacting one side, provided with the rigid protruding microstructure array, of the surface of the sensitive layer prepared in the step (2) with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to protect the device from being influenced by the external environment, so as to prepare the flexible pressure sensor for monitoring the pulse wave.
According to the method, in the step (1), the polymer elastomer precursor solution is polydimethylsiloxane precursor solution, the mass ratio of basic components to the curing agent in the polydimethylsiloxane precursor solution is 10:1, and the elastic polymer solution is thermoplastic polyurethane solution or hydrogenated styrene-butadiene block copolymer solution;
when the polymer elastomer precursor solution is coated, the curing temperature is 70-120 ℃, and the curing time is 60-180 minutes;
when the elastic polymer solution is coated, the curing temperature is 50-80 ℃, and the curing time is 12-24 hours.
In the method, the additive manufacturing technology in the step (2) is a pneumatic direct writing technology, an ammeter jet printing technology or an electrostatic spinning technology;
the curing temperature in the step (2) is 70-100 ℃, and the curing time is 60-120 minutes.
In the above method, the polymer film in step (3) is made of polyimide, polyethylene terephthalate, or polydimethylsiloxane;
the ultrasonic cleaning time is 0.1-0.5 h;
the plasma treatment time is 10-30 minutes;
the metal conductive material is more than one of gold, silver and copper;
the deposition mode of the metal conductive material is more than one of vacuum evaporation, magnetron sputtering and screen printing;
in the method, the adhesive in the step (4) is more than one of polydimethylsiloxane precursor solution, polyimide insulating tape and polyurethane medical tape;
two electrodes of the interdigital electrode are connected through a lead and fixed by conductive adhesive;
the conducting wire is a copper wire or a copper foil, and the conducting adhesive is conducting silver paste or conducting carbon paste.
The principle of the invention is as follows:
the microstructure and the sensitive layer of the flexible pressure sensor prepared in the prior art are made of flexible polymer elastomers, and the flexible polymer materials have viscoelasticity, so that the flexible pressure sensor has high damping property and hysteresis for mechanical stimulation, the external force stimulation can be absorbed by the high damping property and the hysteresis, and the external force stimulation is converted into the energy of polymer chain segment movement, so that the response to the external force stimulation is weakened, the tiny external force cannot be detected, the lower limit of mechanical detection of the flexible pressure sensor is high, the sensitivity of the sensor is low, the response speed is low, and the high-resolution and high-quality detection of pulse wave characteristic peaks cannot be realized. The invention develops a new method, a rigid raised microstructure is constructed on the surface of a flexible sensitive layer, the rigid microstructure has no lag and no damping to the response of mechanical stimulation, and the external force can be completely converted into self deformation, so that the pressure sensor is endowed with high sensitivity, high response speed and low mechanical detection lower limit; in addition, the flexible sensitive layer is attached on the surface of the skin of a human body in a conformal mode, and the flexible wearable performance of the sensor can be guaranteed. Therefore, the rigid microstructure can improve the sensitivity and response speed of the pressure sensor and reduce the mechanical detection lower limit of the sensor, and the flexible sensitive layer can ensure that the sensor is attached to the skin of a human body in a conformal manner, so that the sensor can realize high-resolution wearable continuous monitoring on a weak mechanical signal, namely a pulse wave signal, under the combined action of the rigid microstructure and the flexible sensitive layer (namely under the effect of 'rigidity and flexibility' effect).
Has the beneficial effects that:
(1) the rigid raised microstructure constructed on the surface of the flexible sensitive layer has no lag and no damping on the response of the mechanical stimulation, and can endow the pressure sensor with high sensitivity, high response speed and low detection lower limit performance;
(2) the flexible sensitive layer can be attached on the surface of human skin in a conformal manner, so that the sensor is endowed with flexible wearable performance;
(3) the effect of 'hardness and softness' of the rigid microstructure and the flexible sensitive layer can realize high-resolution wearable continuous monitoring of the sensor on human pulse wave signals;
(4) the flexible pressure sensor has the advantages of simple preparation method and low production cost, and is suitable for large-scale industrial production.
Drawings
FIG. 1 is a schematic structural view of a flexible pressure sensor of the present invention;
FIG. 2 is an optical micrograph of a sensitive layer having an array of rigid microstructures prepared in example 1;
FIG. 3 is a graph showing the change of resistance signal under the cyclic pressure of the flexible pressure sensor prepared in example 1;
FIG. 4 is a diagram illustrating the pulse wave signals of the radial artery of a human body measured by the flexible pressure sensor prepared in example 1;
FIG. 5 shows a human radial pulse wave signal measured by the flexible pressure sensor prepared in comparative example 1;
the sensor comprises a sensitive layer 1, a rigid protruding microstructure array 2 and an interdigital electrode 3.
Detailed Description
The present invention will be further described with reference to the following embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications can be made by those skilled in the art after reading the contents of the present invention, and those equivalents also fall within the scope of the invention defined by the appended claims.
In the embodiment of the invention, the mass ratio of the basic components in the polydimethylsiloxane precursor solution to the curing agent is 10: 1.
Example 1
A flexible pressure sensor for monitoring pulse waves is specifically prepared by the following steps:
(1) uniformly coating a layer of polydimethylsiloxane precursor solution on a plane die, placing the die in an oven, curing for 3 hours at 90 ℃, and removing the film to obtain a polymer elastomer film with the thickness of 0.3 mm;
(2) constructing a raised microstructure array based on conductive silver slurry on the surface of a polymer elastomer film by a pneumatic direct writing technology, heating and curing at 80 ℃ for 120 minutes to form a rigid raised microstructure array based on conductive silver, and preparing a sensitive layer;
the shape of the bulge in the prepared rigid bulge microstructure array is hemispherical, the diameter of the hemisphere is 0.5mm, and the distance between the centers of two adjacent hemispherical bulges is 1mm, as shown in figure 2;
(3) firstly, ultrasonically cleaning a polymer film in acetone, ethanol and deionized water for 0.2h in sequence, drying, then carrying out plasma treatment on the surface of the polymer film for 10 minutes, then covering a mask plate with an interdigital structure on the polymer film, then depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain an interdigital electrode;
wherein the polymer film is made of polyimide; the metal conductive material is silver; the deposition mode of the metal conductive material is vacuum evaporation;
the metal thickness of the prepared interdigital electrode is 120 nm; the length of the interdigital electrode is 15mm, the width of the interdigital electrode is 15mm, and the finger width and the finger distance of the interdigital are 0.5 mm;
(4) contacting one side, provided with the rigid protruding microstructure array, of the surface of the sensitive layer prepared in the step (2) with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to protect the device from being influenced by external environment to prepare the flexible pressure sensor for monitoring pulse waves;
wherein the adhesive is polydimethylsiloxane precursor solution; two electrodes of the interdigital electrode are connected through a copper wire and fixed by conductive silver paste;
the prepared flexible pressure sensor for monitoring the pulse wave comprises a sensitive layer 1 and an interdigital electrode 3, wherein the sensitive layer is a polymer elastomer film with a rigid raised microstructure array 2 on the surface, and the rigid raised microstructure array is a raised microstructure array based on conductive silver as shown in figure 1.
The resistance signal change of the flexible pressure sensor for monitoring the pulse waves under the action of pressure is measured through the digital source meter, so that the sensing performance of the flexible pressure sensing device for monitoring the pulse waves can be obtained. The highest sensitivity of the flexible pressure sensor for monitoring the pulse wave is 24.2kPa -1 The response time is 13ms, and the lower limit of mechanical detection is 3.5Pa, so that the flexible pressure sensor for monitoring the pulse wave has the performances of high sensitivity, high response speed and low lower limit of mechanical detection. And the resistance signal change of the flexible pressure sensor for monitoring the pulse wave under the action of the cyclic pressure has excellent stability and repeatability, and the resistance signal change under the action of the cyclic pressure of 20Pa is shown in figure 3.
As shown in fig. 4, the flexible pressure sensor for monitoring pulse wave is attached to the radial artery of wrist, so that the characteristic peak included in the pulse wave signal of human body can be monitored with high resolution.
Comparative example 1
The specific steps of the flexible pressure sensor are basically the same as those of embodiment 1, and the difference is that the preparation method of the sensitive layer comprises the following steps: uniformly coating a layer of polydimethylsiloxane precursor solution on a die with a hemispherical groove array, heating and curing, uncovering the film to obtain an elastomer film with a flexible hemispherical convex microstructure array, and evaporating a layer of conductive silver on the surface of the elastomer film to obtain a sensitive layer; the thickness of the elastomer film is 0.3mm, the diameter of each hemispherical protrusion is 0.5mm, the distance between the centers of two adjacent hemispherical protrusions is 1.0mm, and the thickness of the conductive silver is 100 nm.
The maximum sensitivity of the prepared flexible pressure sensor is 1.15kPa -1 The response time is 180ms, and the lower limit of mechanical detection is 45 Pa. As shown in fig. 5, the flexible pressure sensor is attached to the radial artery of the wrist, and only the pulsation of the pulse wave can be roughly measured, and the characteristic peak included in the pulse wave signal cannot be measured with high resolution.
Comparing the example 1 with the comparative example 1, it can be seen that the rigid microstructure constructed on the surface of the flexible sensitive layer has no lag and no damping to the response of the mechanical stimulation, can endow the flexible pressure sensor with high sensitivity, fast response and low detection lower limit performance, and can realize high-resolution monitoring of pulse wave signals.
Example 2
A flexible pressure sensor for monitoring pulse waves is prepared by the following specific steps:
(1) uniformly coating a layer of polydimethylsiloxane precursor solution on a plane mould, placing the mould in an oven, curing for 1h at 120 ℃, and removing the film to obtain a polymer elastomer film with the thickness of 0.2 mm;
(2) constructing a conductive gold slurry-based protruding microstructure array on the surface of the polymer elastomer film by an amperometric jet printing technology, and heating and curing at 70 ℃ for 100 minutes to form a conductive gold-based rigid protruding microstructure array to prepare a sensitive layer;
the shape of the bulge in the prepared rigid bulge microstructure array is hemispherical, the diameter of the hemisphere is 0.15mm, and the distance between the centers of two adjacent hemispherical bulges is 0.3 mm;
(3) firstly, ultrasonically cleaning a polymer film in acetone, ethanol and deionized water for 0.4h in sequence, drying, then carrying out plasma treatment on the surface of the polymer film for 15 minutes, then covering a mask plate with an interdigital structure on the polymer film, then depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain an interdigital electrode;
wherein the polymer film is made of polyethylene terephthalate; the metal conductive material is gold; the deposition mode of the metal conductive material is magnetron sputtering;
the metal thickness of the prepared interdigital electrode is 120 nm; the length of the interdigital electrode is 12mm, the width of the interdigital electrode is 12mm, and the finger width and the finger spacing of the interdigital are 0.2 mm;
(4) contacting one side, provided with the rigid protruding microstructure array, of the surface of the sensitive layer prepared in the step (2) with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to protect the device from being influenced by an external environment to prepare a flexible pressure sensor for monitoring pulse waves;
wherein the adhesive is a polyimide insulating tape; two electrodes of the interdigital electrode are connected through a copper foil and fixed by conductive carbon paste;
the manufactured flexible pressure sensor for monitoring the pulse wave comprises a sensitive layer 1 and an interdigital electrode 3, wherein the sensitive layer is a polymer elastomer film with a rigid protruding microstructure array 2 on the surface, and the rigid protruding microstructure array is a protruding microstructure array based on conductive gold, as shown in figure 1.
The highest sensitivity of the flexible pressure sensor for monitoring the pulse wave is 35.2kPa -1 The response time is 9ms, and the lower limit of mechanical detection is 2.8 Pa.
Example 3
A flexible pressure sensor for monitoring pulse waves is specifically prepared by the following steps:
(1) uniformly coating a layer of thermoplastic polyurethane solution on a plane mould, placing the mould in an oven, curing for 24 hours at 50 ℃, and then uncovering the film to obtain a polymer elastomer film with the thickness of 0.38 mm;
(2) constructing a conductive copper slurry-based raised microstructure array on the surface of a polymer elastomer film by an electrostatic spinning technology, and heating and curing at 100 ℃ for 80 minutes to form a conductive copper-based rigid raised microstructure array to prepare a sensitive layer;
the shape of the bulge in the prepared rigid bulge microstructure array is hemispherical, the diameter of the hemisphere is 0.25mm, and the distance between the centers of two adjacent hemispherical bulges is 0.5 mm;
(3) firstly, ultrasonically cleaning a polymer film in acetone, ethanol and deionized water for 0.3h in sequence, drying, then carrying out plasma treatment on the surface of the polymer film for 30 minutes, then covering a mask plate with an interdigital structure on the polymer film, then depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain an interdigital electrode;
wherein the polymer film is made of polydimethylsiloxane; the metal conductive material is copper; the deposition mode of the metal conductive material is screen printing;
the metal thickness of the prepared interdigital electrode is 160 nm; the length of the interdigital electrode is 18mm, the width of the interdigital electrode is 18mm, and the finger width and the finger spacing of the interdigital are 0.8 mm;
(4) contacting one side, provided with the rigid protruding microstructure array, of the surface of the sensitive layer prepared in the step (2) with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to protect the device from being influenced by external environment to prepare the flexible pressure sensor for monitoring pulse waves;
wherein the adhesive is a polyurethane medical adhesive tape; two electrodes of the interdigital electrode are connected through a copper wire and fixed by conductive silver paste;
the manufactured flexible pressure sensor for monitoring the pulse wave comprises a sensitive layer 1 and an interdigital electrode 3, wherein the sensitive layer is a polymer elastomer film with a rigid raised microstructure array 2 on the surface, and the rigid raised microstructure array is a raised microstructure array based on conductive copper, as shown in figure 1.
The highest sensitivity of the flexible pressure sensor for monitoring the pulse wave is 19.6kPa -1 The response time is 16ms, and the lower limit of mechanical detection is 5.7 Pa.
Example 4
A flexible pressure sensor for monitoring pulse waves is prepared by the following specific steps:
(1) uniformly coating a layer of thermoplastic polyurethane solution on a plane mould, placing the mould in an oven, curing for 20 hours at 60 ℃, and then uncovering the film to obtain a polymer elastomer film with the thickness of 0.4 mm;
(2) constructing a conductive silver paste-based raised microstructure array on the surface of a polymer elastomer film by a pneumatic direct writing technology, and heating and curing at 90 ℃ for 90 minutes to form a conductive silver-based rigid raised microstructure array to prepare a sensitive layer;
the shape of the bulge in the prepared rigid bulge microstructure array is hemispherical, the diameter of the hemisphere is 0.8mm, and the distance between the centers of two adjacent hemispherical bulges is 1.6 mm;
(3) firstly, sequentially ultrasonically cleaning a polymer film in acetone, ethanol and deionized water for 0.5h, drying, then carrying out plasma treatment on the surface of the polymer film for 10 minutes, then covering a mask plate with an interdigital structure on the polymer film, then depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain an interdigital electrode;
wherein the polymer film is made of polyimide; the metal conductive material is gold; the deposition mode of the metal conductive material is vacuum evaporation;
the metal thickness of the prepared interdigital electrode is 200 nm; the length of the interdigital electrode is 20mm, the width of the interdigital electrode is 20mm, and the finger width and the finger distance of the interdigital are 1.6 mm;
(4) contacting one side, provided with the rigid protruding microstructure array, of the surface of the sensitive layer prepared in the step (2) with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to protect the device from being influenced by external environment to prepare the flexible pressure sensor for monitoring pulse waves;
wherein the adhesive is polydimethylsiloxane precursor solution; two electrodes of the interdigital electrode are connected through a copper foil and are fixed by conductive carbon paste;
the prepared flexible pressure sensor for monitoring the pulse wave comprises a sensitive layer 1 and an interdigital electrode 3, wherein the sensitive layer is a polymer elastomer film with a rigid raised microstructure array 2 on the surface, and the rigid raised microstructure array is a raised microstructure array based on conductive silver as shown in figure 1.
The highest sensitivity of the flexible pressure sensor for monitoring the pulse wave is 9.5kPa -1 The response time is 26ms, and the lower limit of mechanical detection is 7.6 Pa.
Example 5
A flexible pressure sensor for monitoring pulse waves is prepared by the following specific steps:
(1) uniformly coating a layer of hydrogenated styrene-butadiene block copolymer solution on a plane mould, placing the mould in an oven, curing for 16h at 70 ℃, and removing the film to obtain a polymer elastomer film with the thickness of 0.35 mm;
(2) constructing a conductive gold slurry-based protruding microstructure array on the surface of the polymer elastomer film by an amperometric jet printing technology, and heating and curing at 80 ℃ for 80 minutes to form a conductive gold-based rigid protruding microstructure array to prepare a sensitive layer;
the shape of the bulge in the prepared rigid bulge microstructure array is hemispherical, the diameter of the hemisphere is 0.7mm, and the distance between the centers of two adjacent hemispherical bulges is 1.4 mm;
(3) firstly, ultrasonically cleaning a polymer film in acetone, ethanol and deionized water for 0.1h in sequence, drying, then carrying out plasma treatment on the surface of the polymer film for 25 minutes, then covering a mask plate with an interdigital structure on the polymer film, then depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain an interdigital electrode;
wherein the polymer film is made of polyethylene terephthalate; the metal conductive material is silver; the deposition mode of the metal conductive material is magnetron sputtering;
the metal thickness of the prepared interdigital electrode is 160 nm; the length of the interdigital electrode is 15mm, the width of the interdigital electrode is 15mm, and the finger width and the finger distance of the interdigital are 1.6 mm;
(4) contacting one side, provided with the rigid protruding microstructure array, of the surface of the sensitive layer prepared in the step (2) with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to protect the device from being influenced by external environment to prepare the flexible pressure sensor for monitoring pulse waves;
wherein the adhesive is a polyimide insulating tape; two electrodes of the interdigital electrode are connected through a copper wire and fixed by conductive silver paste;
the manufactured flexible pressure sensor for monitoring the pulse wave comprises a sensitive layer 1 and an interdigital electrode 3, wherein the sensitive layer is a polymer elastomer film with a rigid protruding microstructure array 2 on the surface, and the rigid protruding microstructure array is a protruding microstructure array based on conductive gold, as shown in figure 1.
The highest sensitivity of the flexible pressure sensor for monitoring the pulse wave is 27.2kPa -1 The response time is 22ms, and the lower limit of mechanical detection is 5.8 Pa.
Example 6
A flexible pressure sensor for monitoring pulse waves is prepared by the following specific steps:
(1) uniformly coating a layer of hydrogenated styrene-butadiene block copolymer solution on a plane mould, placing the mould in an oven, curing for 12 hours at 80 ℃, and uncovering the film to obtain a polymer elastomer film with the thickness of 0.45 mm;
(2) constructing a conductive copper slurry-based raised microstructure array on the surface of a polymer elastomer film by an electrostatic spinning technology, and heating and curing at 80 ℃ for 60 minutes to form a conductive copper-based rigid raised microstructure array to prepare a sensitive layer;
the shape of the bulge in the prepared rigid bulge microstructure array is hemispherical, the diameter of the hemisphere is 0.5mm, and the distance between the centers of two adjacent hemispherical bulges is 1.3 mm;
(3) firstly, ultrasonically cleaning a polymer film in acetone, ethanol and deionized water for 0.3h in sequence, drying, then carrying out plasma treatment on the surface of the polymer film for 20 minutes, then covering a mask plate with an interdigital structure on the polymer film, then depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain an interdigital electrode;
wherein the polymer film is made of polydimethylsiloxane; the metal conductive material is copper; the deposition mode of the metal conductive material is screen printing;
the metal thickness of the prepared interdigital electrode is 160 nm; the length of the interdigital electrode is 16mm, the width of the interdigital electrode is 16mm, and the finger width and the finger distance of the interdigital are 1.1 mm;
(4) contacting one side, provided with the rigid protruding microstructure array, of the surface of the sensitive layer prepared in the step (2) with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to protect the device from being influenced by external environment to prepare the flexible pressure sensor for monitoring pulse waves;
wherein the adhesive is a polyurethane medical adhesive tape; two electrodes of the interdigital electrode are connected through a copper foil and fixed by conductive carbon paste;
the manufactured flexible pressure sensor for monitoring the pulse wave comprises a sensitive layer 1 and an interdigital electrode 3, wherein the sensitive layer is a polymer elastomer film with a rigid protruding microstructure array 2 on the surface, and the rigid protruding microstructure array is a protruding microstructure array based on conductive copper.
The highest sensitivity of the flexible pressure sensor for monitoring the pulse wave is 40.6kPa -1 The response time is 11ms, and the lower limit of mechanical detection is 3.7 Pa.
Claims (10)
1. A flexible pressure sensor for monitoring pulse waves comprises a sensitive layer and interdigital electrodes, wherein two electrodes of the interdigital electrodes are connected through a lead, and the flexible pressure sensor is characterized in that: the sensitive layer is a polymer elastomer film with a rigid raised microstructure array on the surface;
the rigid raised microstructure array is a raised microstructure array based on conductive metal;
the highest sensitivity of the flexible pressure sensor is not lower than 9.5kPa -1 The response time is not higher than 30ms, and the lower limit of mechanical detection is not higher than 8 Pa.
2. A flexible pressure sensor for monitoring pulse waves according to claim 1, characterized in that said conductive metal is gold, silver or copper.
3. A flexible pressure sensor for monitoring pulse waves according to claim 1, wherein the polymer elastomer film has a thickness of 0.2 to 0.5 mm;
the metal thickness of the interdigital electrode is 100-200 nm; the length of the interdigital electrode is 10-20 mm, the width is 10-20 mm, and the finger width and the finger distance of the interdigital are 0.2-2.0 mm.
4. The flexible pressure sensor according to claim 3, wherein the protrusions of the rigid protrusion microstructure array are hemispheric, the diameter of each hemisphere is 0.1-1.0 mm, and the distance between centers of two adjacent hemispheric protrusions is 0.15-1.5 mm.
5. Preparing a flexible pressure sensor for monitoring pulse waves according to any one of claims 1 to 4, characterized in that: respectively preparing the sensitive layer and the interdigital electrode, and assembling to obtain the flexible pressure sensor for monitoring the pulse wave;
the rigid raised microstructure array on the surface of the sensitive layer is prepared by an additive manufacturing technology.
6. The method according to claim 5, characterized by comprising the following steps:
(1) uniformly coating a layer of polymer elastomer precursor solution or elastic polymer solution on a plane mould, placing the mould in an oven for complete curing, and uncovering the film to obtain a polymer elastomer film;
(2) constructing a conductive metal slurry-based raised microstructure array on the surface of the polymer elastomer film by an additive manufacturing technology, and heating and curing to form a conductive metal-based rigid raised microstructure array to prepare the sensitive layer;
(3) firstly, sequentially ultrasonically cleaning a polymer film in acetone, ethanol and deionized water, drying, then carrying out plasma treatment on the surface of the polymer film, then covering a mask plate with an interdigital structure on the polymer film, depositing a metal conductive material on the polymer film, and finally taking down the mask plate to obtain the interdigital electrode;
(4) and (3) contacting one side of the surface of the sensitive layer prepared in the step (2) with the rigid raised microstructure array with the electrode surface of the interdigital electrode prepared in the step (3), and packaging by using an adhesive to prepare the flexible pressure sensor for monitoring the pulse wave.
7. The method of claim 6, wherein the polymer elastomer precursor solution in step (1) is a polydimethylsiloxane precursor solution, the elastomeric polymer solution is a thermoplastic polyurethane solution or a hydrogenated styrene-butadiene block copolymer solution;
when the polymer elastomer precursor solution is coated, the curing temperature is 70-120 ℃, and the curing time is 60-180 minutes;
when the elastic polymer solution is coated, the curing temperature is 50-80 ℃ and the curing time is 12-24 h.
8. The method of claim 6, wherein the additive manufacturing technique in step (2) is a pneumatic direct writing technique, an amperometric jet printing technique or an electrospinning technique;
the curing temperature in the step (2) is 70-100 ℃, and the curing time is 60-120 minutes.
9. The method according to claim 6, wherein the polymer film in step (3) is made of polyimide, polyethylene terephthalate or polydimethylsiloxane;
the ultrasonic cleaning time is 0.1-0.5 h;
the plasma treatment time is 10-30 minutes;
the metal conductive material is more than one of gold, silver and copper;
the deposition mode of the metal conductive material is more than one of vacuum evaporation, magnetron sputtering and screen printing.
10. The method according to claim 6, wherein the adhesive in the step (4) is one or more of polydimethylsiloxane precursor solution, polyimide insulating tape and polyurethane medical tape;
two electrodes of the interdigital electrode are connected through a lead and fixed by conductive adhesive;
the conducting wire is a copper wire or a copper foil, and the conducting adhesive is conducting silver paste or conducting carbon paste.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115855324A (en) * | 2022-12-26 | 2023-03-28 | 厦门大学 | Thin film pressure sensor for detecting expansion of lithium battery cell and preparation method thereof |
| CN117297757A (en) * | 2023-11-27 | 2023-12-29 | 中国科学院深圳先进技术研究院 | Multichannel balloon electrode and preparation method and application thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115855324A (en) * | 2022-12-26 | 2023-03-28 | 厦门大学 | Thin film pressure sensor for detecting expansion of lithium battery cell and preparation method thereof |
| CN115855324B (en) * | 2022-12-26 | 2024-04-30 | 厦门大学 | Film pressure sensor for detecting expansion of lithium battery core and preparation method thereof |
| CN117297757A (en) * | 2023-11-27 | 2023-12-29 | 中国科学院深圳先进技术研究院 | Multichannel balloon electrode and preparation method and application thereof |
| CN117297757B (en) * | 2023-11-27 | 2024-03-15 | 中国科学院深圳先进技术研究院 | Multichannel balloon electrode and preparation method and application thereof |
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