Flexible pressure sensor for breath detection
By using a conical microstructure flexible pressure sensor with copper electrodes and PDMS/MWCNTs composite material, the problem of poor portability of respiratory detection devices has been solved, achieving high sensitivity and stability in detecting changes in laryngeal pressure, and featuring low power consumption and long lifespan.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-04
- Publication Date
- 2026-04-03
AI Technical Summary
Existing respiratory detection devices are not portable and are difficult to efficiently and accurately detect minute and large changes in laryngeal respiratory pressure in complex environments.
A flexible pressure sensor employing a conical microstructure utilizes copper electrodes and PDMS/MWCNTs composite materials, combined with a conductive path design, to achieve high sensitivity and stability in detecting throat pressure signals.
It improves the sensitivity and stability of the sensor, enabling it to accurately detect minute and large changes in respiratory pressure under different environments, and features low power consumption, long lifespan, and easy integration.
Smart Images
Figure CN224070450U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pressure sensing technology, specifically, it relates to a flexible pressure sensor for respiratory detection. Background Technology
[0002] With the continuous advancement of technology, people's demand for health monitoring is increasing, leading to the emergence of flexible pressure sensors in respiratory detection. In the traditional medical field, respiratory detection often relies on large-scale testing equipment. While these devices offer high accuracy, they suffer from poor portability and limited application scenarios. The advent of flexible pressure sensors has brought new opportunities for respiratory detection. Flexible pressure sensors can detect respiratory intensity by measuring minute pressure changes in the throat, greatly improving detection efficiency. By analyzing the strength and frequency of breathing, the condition of respiratory system diseases can be effectively analyzed. Its soft and flexible properties allow it to better conform to human skin, enabling real-time monitoring without interfering with normal bodily activities.
[0003] Meanwhile, advancements in microelectronics technology have enabled the miniaturization and integration of sensors, further improving their performance and reliability. Against the backdrop of the rise of the Internet of Things and smart wearable devices, people desire to monitor their health anytime, anywhere. Flexible pressure sensors, due to their unique advantages, can be integrated into various wearable devices, such as smart bracelets and smart clothing, providing technical support for convenient respiratory detection and creating conditions for the development of personal health management and telemedicine.
[0004] Therefore, it is crucial to design a low-cost, small-sized, and high-precision flexible pressure sensor for respiratory detection. Utility Model Content
[0005] In respiratory monitoring, the range of pressure changes in the larynx is quite wide, encompassing minute pressure fluctuations during slow breathing and relatively large pressure changes during rapid breathing. During normal breathing, pressure changes are relatively gradual and small, but in special situations such as deep breathing, coughing, or rapid breathing, the magnitude and rate of pressure changes increase. This requires sensors that can sensitively capture minute pressure changes, maintain accurate responses even with large pressure fluctuations, and exhibit good linearity across the entire pressure range to accurately reflect the true state of breathing.
[0006] To address the aforementioned technical problems, this invention provides a flexible pressure sensor for respiratory detection, which achieves pressure sensing through the piezoresistive effect. A conical microstructure is utilized to enhance the sensor's response and sensitivity, enabling precise and efficient detection of respiratory signals.
[0007] This utility model discloses a flexible pressure sensor for respiratory detection, including a first protective layer, a first electrode layer, a conical pressure-sensitive array, a flexible substrate, a second electrode layer, and a second protective layer; the conical pressure-sensitive array is composed of conical microstructures and is located in the middle of the first electrode layer and the flexible substrate; the second electrode layer is located on the lower side of the flexible substrate; the first and second protective layers are located on the upper and lower sides of the first and second electrode layers, respectively.
[0008] Preferably, the first and second electrode layers are made of copper, which has excellent electrical conductivity. In respiratory detection, the good conductivity of the flexible pressure sensor ensures rapid and stable transmission of electrical signals. This allows the sensor to quickly respond to changes in laryngeal pressure caused by breathing and accurately convert the respiratory pressure signal into an electrical signal output. Whether it's a small pressure fluctuation or a large pressure change, the copper electrode can efficiently conduct current, ensuring the sensor's sensitivity and response speed. Furthermore, the copper electrode has a certain degree of flexibility, with a thickness of 0.5–1.0 mm, allowing it to adapt to bending, stretching, and other deformations in different scenarios, ensuring the sensor can operate normally in various complex environments.
[0009] Preferably, the conical pressure-sensitive array is made of PDMS / MWCNTs composite material. PDMS is a polymer material with excellent flexibility, capable of undergoing significant deformation under external force without easily breaking. MWCNTs, multi-walled carbon nanotubes, possess excellent electrical conductivity. In the PDMS / MWCNTs composite material, MWCNTs act as conductive fillers, uniformly distributed within the PDMS matrix, forming numerous conductive pathways and significantly improving the composite material's conductivity. This enables the sensor to quickly and accurately convert pressure signals into electrical signals, thereby achieving precise measurement of respiratory signals.
[0010] To enhance the accuracy of respiratory signal detection and improve sensor sensitivity, preferably, the conical microstructure in the conical pressure-sensitive array has a diameter of 0.5–1.0 mm and a height of 1.0–1.5 mm. When the sensor is subjected to respiratory pressure, the conical pressure-sensitive array is compressed, and the conical microstructure guides stress concentration on the microstructure, resulting in greater deformation of the pressure-sensitive array and thus a more significant change in the conductive path. As the respiratory pressure increases, the contact area between the conical pressure-sensitive array and the first electrode layer increases, and the resistance decreases rapidly, giving the sensor strong responsiveness and high sensitivity, making it suitable for respiratory detection under minute pressures.
[0011] Furthermore, the introduction of the conical microstructure reduces the initial contact area between the sensor's first electrode layer and the conical pressure-sensitive array. This decreases the sensor's resistance at zero pressure, making the sensor more sensitive. For example, during the detection of gentle breathing, even a small pressure change can cause significant deformation of the conical microstructure, leading to a significant change in resistance and enabling sensitive breath detection.
[0012] To enhance the stability and sensitivity of the sensor, preferably, the conical pressure-sensitive array has a length of 0.5–1.0 cm and a width of 0.5–1.0 cm. The conical pressure-sensitive array consists of multiple conical microstructure units that can work collaboratively. The resistance change signals generated by each unit are transmitted simultaneously, effectively sensing and converting throat pressure from multiple different locations. This provides a more comprehensive reflection of the pressure distribution on the sensor surface and improves the sensitivity of detecting changes in respiratory pressure.
[0013] Furthermore, the multiple conical microstructure units in the conical pressure-sensitive array can calibrate and compensate for each other. If the response of a certain unit deviates, when calculating the overall pressure change, the influence of the abnormal unit is reduced through a weighted average based on the resistance changes of other units, ensuring that the overall pressure measurement result output by the sensor remains accurate, thus improving the stability and measurement accuracy of the sensor. During long-term use, this characteristic helps maintain the stability of the sensor's performance and reduces measurement errors.
[0014] To improve the flexibility and stability of the sensor, the flexible substrate is preferably made of PDMS / MWCNTs composite material with a thickness of 0.5–1.0 mm. When the respiratory pressure in the throat changes, the flexible substrate deforms along with the conical pressure-sensitive array, ensuring that the sensor's response to pressure is not hindered by the rigidity of the substrate, thus improving the sensor's flexibility. Furthermore, the presence of MWCNTs makes the flexible substrate conductive as well. The contact between the flexible substrate and the second electrode layer forms a conductive path, facilitating the conduction of electrical signals within the sensor. When the conical pressure-sensitive array experiences resistance changes due to pressure variations, generating electrical signals, the flexible substrate can act as an auxiliary conductive medium, helping the electrical signals to be transmitted to the electrode layer more stably and quickly, improving the sensor's response speed and stability.
[0015] To improve the sensor's water resistance and lifespan, preferably, the first and second protective layers are made of PDMS coated with a Zn thin film, with a PDMS thickness of 0.5–1.0 mm and a Zn layer thickness of 250–350 nm. PDMS has excellent water resistance, effectively preventing moisture from entering the sensor. This is crucial for microstructured flexible pressure sensors, as moisture can degrade or even damage the pressure-sensitive layer. The presence of Zn further enhances the water resistance of the protective layer and also prevents corrosion and oxidation of the sensor in humid environments. Furthermore, Zn possesses electromagnetic shielding properties, reducing the impact of external electromagnetic interference on the sensor. The PDMS Zn thin film protective layer can shield external electromagnetic signals to a certain extent, improving the sensor's anti-interference capability.
[0016] The technical solution of this utility model is as follows: When the sensor detects respiratory pressure in the throat, the conical pressure-sensitive array comes into contact with the copper electrode, forming a conductive path. As the respiratory pressure increases, the contact area between the conical pressure-sensitive array and the electrode increases rapidly, and the resistance decreases rapidly, resulting in a significant change in resistance. Based on the piezoresistive effect formula:
[0017]
[0018] Where l represents the length of the composite material, S represents the cross-sectional area of the composite material, and ρ represents the resistivity of the composite material. Stable detection of respiratory signals is achieved by measuring the sensor resistance.
[0019] This invention provides a flexible pressure sensor for respiratory detection, which uses a unique conical microstructure cone-shaped pressure-sensitive array as the sensitive unit for detecting laryngeal pressure signals. When applied to respiratory detection, it significantly improves sensitivity, response performance, and stability. At the same time, it also has advantages such as simple structure, low power consumption, long life, easy integration, low measurement error, small size, and process compatibility. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of a high-sensitivity flexible pressure sensor according to this utility model.
[0021] Figure 2 This is a sensor sensitivity test chart.
[0022] Figure 3 This is a test diagram of the stability of the sensor's electrical signal.
[0023] Wherein, 1 is the first protective layer; 2 is the first electrode layer; 3 is the conical pressure-sensitive array; 4 is the flexible substrate; 5 is the second electrode layer; and 6 is the second protective layer. Detailed Implementation
[0024] The embodiments of this utility model are described in detail below, and examples of these embodiments are shown in the accompanying drawings.
[0025] This utility model discloses a high-sensitivity flexible pressure sensor, including a first protective layer 1, a first electrode layer 2, a conical pressure-sensitive array 3, a flexible substrate 4, a second electrode layer 5, and a second protective layer 6; the conical pressure-sensitive array 3 is composed of conical microstructures and is located between the first electrode layer 2 and the flexible substrate 4; the second electrode layer 5 is located on the lower side of the flexible substrate 4; the first protective layer 1 is located on the upper side of the first electrode layer 2, and the second protective layer 6 is located on the lower side of the second electrode layer 5.
[0026] To enhance conductivity and extend the sensor's lifespan, the first electrode layer 2 and the second electrode layer 5 are made of copper, which possesses excellent conductivity. This ensures rapid and stable transmission of electrical signals, allowing the sensor to quickly respond to changes in laryngeal breathing pressure and accurately convert the breathing pressure signal into an electrical signal output. The thickness is set to 1.0 mm to allow the sensor to adapt to various bending and stretching deformations, maximizing wearing comfort and ensuring normal operation for respiratory detection, thus extending the sensor's lifespan.
[0027] To achieve precise conversion between pressure and respiratory signals, the cone-shaped pressure-sensitive array 3 is made of a PDMS / MWCNT composite material. The combination of PDMS and MWCNTs provides a flexible substrate for the sensor. MWCNTs possess excellent conductivity, allowing electrons to rapidly transport within their nanoscale tubular structure. In the PDMS / MWCNT composite, MWCNTs act as conductive fillers, uniformly distributed within the PDMS matrix, forming numerous conductive pathways and significantly improving the composite's conductivity. This enables the sensor to rapidly and accurately convert laryngeal respiratory pressure signals into electrical signals, thereby achieving precise measurement of respiratory signals.
[0028] To enhance the accuracy of respiratory signal detection and improve sensor sensitivity, the conical microstructure in the conical pressure-sensitive array 3 has a diameter of 1.0 mm and a height of 1.5 mm. When the sensor is subjected to respiratory pressure, the conical pressure-sensitive array 3 is compressed. The conical microstructure guides stress concentration on the microstructure, resulting in greater deformation of the pressure-sensitive array and a more significant change in the conductive path. As the respiratory pressure further increases, the contact area between the conical pressure-sensitive array 3 with its microstructure and the first electrode layer 2 increases rapidly, and the resistance decreases rapidly, improving the sensor's response speed and giving it strong responsiveness and high sensitivity. Furthermore, the introduction of the conical microstructure reduces the initial contact area between the sensor's first electrode layer 2 and the conical pressure-sensitive array 3, which reduces the sensor's resistance under zero pressure, making the sensor more sensitive and improving the accuracy of respiratory detection.
[0029] To enhance the stability and sensitivity of the sensor, the conical pressure-sensitive array 3 has a length of 1.0 cm and a width of 1.0 cm. The conical pressure-sensitive array consists of multiple conical microstructure units that can work collaboratively. When pressure is applied to different locations on the sensor, multiple conical microstructure units can respond simultaneously, enabling the sensor to perceive pressure distribution more comprehensively and further improving the sensitivity to pressure changes.
[0030] To improve the flexibility and stability of the sensor, the flexible substrate 4 is made of PDMS / MWCNTs composite material with a thickness of 1.0 mm. When subjected to respiratory pressure from the throat, the flexible substrate 4 deforms along with the conical pressure-sensitive array 3, ensuring that the sensor's response to pressure is not hindered by the rigidity of the substrate, thus improving the sensor's flexibility. Furthermore, the presence of MWCNTs makes the flexible substrate 4 conductive. The flexible substrate 4 forms a conductive path with the second electrode layer 5, facilitating the conduction of electrical signals within the sensor. When the conical pressure-sensitive layer 3 experiences resistance changes due to pressure variations, generating an electrical signal, the flexible substrate 4 acts as an auxiliary conductive medium, helping the electrical signal to be transmitted to the electrode layer more stably and quickly, improving the sensor's response speed and stability.
[0031] To investigate the sensitivity of the flexible pressure sensor, the sensor's sensitivity was tested, and the results are as follows: Figure 2 As shown, with the gradual application of pressure, the sensor exhibits sensing characteristics in three stages: within a small pressure range of 0–0.56 kPa, the sensor displays 25.7 kPa. -1 High sensitivity; exhibits 2.3 kPa within the medium pressure range of 0.56–20.4 kPa. -1 Its sensitivity is high; it exhibits extremely high linearity over a wide pressure range of 20.4–460 kPa, with a sensitivity of 0.13 kPa. -1 It can be seen that the sensor's sensitivity advantage can be applied to respiratory detection, adapting to the detection of both slow and rapid breathing.
[0032] To verify the stability of the sensor, five cycles of pressurization-unloading to zero pressure were performed sequentially at 30 Pa, 68 Pa, 0.34 kPa, 0.62 kPa, 2.1 kPa, 5.7 kPa, 11.3 kPa, and 18.5 kPa. The results are as follows: Figure 3 As shown, the sensor's stable electrical signal response and step stability under stable pressure ensure stable respiratory detection.
[0033] To improve the sensor's water resistance and lifespan, the first protective layer 1 and the second protective layer 6 are made of PDMS coated with a Zn film. PDMS has excellent water resistance, and a 1mm thick PDMS film can effectively prevent moisture from entering the sensor. The presence of Zn further enhances the water resistance of the protective layers. A Zn layer thickness of 350nm provides good water resistance; as the Zn film thickness increases, the sensor's hydrophobicity increases, thus improving water resistance. Considering wearing comfort, a Zn layer thickness of 350nm meets application requirements. Furthermore, Zn possesses certain electromagnetic shielding properties, reducing the impact of external electromagnetic interference on the sensor. The PDMS Zn-coated protective layer can shield external electromagnetic signals to a certain extent, improving the sensor's anti-interference capability.
[0034] The above is a detailed description of the preferred embodiments of the present utility model. However, the present utility model is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present utility model. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.
Claims
1. A flexible pressure sensor for breath detection, characterized in that, The application relates to a piezoelectric sensor, which comprises a first protective layer, a first electrode layer, a conical piezoelectric array, a flexible substrate, a second electrode layer and a second protective layer; the conical piezoelectric array is composed of conical microstructures and is located in the middle of the first electrode layer and the flexible substrate; The second electrode layer is located on the lower side of the flexible substrate; the first and second protective layers are respectively located on the upper and lower sides of the first and second electrode layers.
2. A flexible pressure sensor for breath detection according to claim 1, wherein, The material of the first electrode layer and the second electrode layer is copper, and the thickness is 0.5-1.0 mm.
3. The flexible pressure sensor for breath detection of claim 1, wherein, The material of the conical piezoelectric array is a PDMS / MWCNTs composite material.
4. The flexible pressure sensor for breath detection of claim 1, wherein, The diameter of the conical microstructure in the conical piezoelectric array is 0.5-1.0 mm, and the height is 1.0-1.5 mm.
5. The flexible pressure sensor for breath detection of claim 1, wherein, The length of the conical piezoelectric array is 0.5-1.0 cm, and the width is 0.5-1.0 cm.
6. The flexible pressure sensor for breath detection of claim 1, wherein, The material of the flexible substrate is a PDMS / MWCNTs composite material, and the thickness is 0.5-1.0 mm.
7. The flexible pressure sensor for breath detection of claim 1, wherein, The material of the first protective layer and the second protective layer is a PDMS Zn-coated film, the thickness of the PDMS is 0.5-1.0 mm, and the thickness of the Zn layer is 250-350 nm.