Non-contact hydrogel mixture elastic property measuring system

Abstract

The invention discloses a non-contact hydrogel mixture elastic property measuring system, which comprises a pressure module, a pressure measuring module, a data processing module, a data processing module, a data processing module and a data processing module, and is characterized in that the pressure module is used for generating and non-contact applying ultrasonic pressure to hydrogel; an illumination module configured to provide a terahertz radiation illumination beam; an optical module arranged in an optical path of the illumination module for forwarding and directing at least a portion of the terahertz radiation illumination beam onto the hydrogel of the subject and receiving at least a portion of the terahertz radiation reflected from the hydrogel to provide a beam of returned terahertz radiation; a terahertz detection module configured to provide a detection signal by detecting the returned terahertz radiation; and the signal processing module is configured to communicate with the terahertz detection module so as to receive a detection signal. The non-contact hydrogel mixture elastic property measuring system disclosed by the invention overcomes the problems that in the prior art, contact detection is needed, and the detection scheme is complex.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogel property measurement, and in particular relates to a non-contact hydrogel mixture elastic property measurement system. Background Art

[0002] Hydrogels are water-containing gels composed of a 3D network of polymers (molecules made up of repeating units), physically entangled and cross-linked together by chemical bonds. When the mixture cools the polymers cross-link with each other, forming a network that holds water molecules, forming a solid hydrogel, and this process can be reversed by raising the temperature again. By changing the polymers used and the type of cross-links made, hydrogels can have different properties and numerous applications. Some are biocompatible and can be used in the body to deliver drugs, others can remove pollutants from water, and some are even used as manufacturing materials for soft robots, and so on.

[0003] Existing methods for detecting hydrogel mixtures include gold standard methods such as high performance liquid chromatography (HPLC), gas chromatography (GC) and mass spectrometry (MS). Although these methods have shown powerful trace analysis capabilities, the need for complex instruments, trained technicians and time-consuming processes severely limit their on-site applications. At the same time, the above methods often require samples to be obtained for operation, and non-contact detection cannot be achieved.

[0004] Therefore, further improvements are made to the above problems. Summary of the invention

[0005] The main purpose of the present invention is to provide a non-contact hydrogel mixture elastic property measurement system, to overcome the problem of contact detection and complex detection scheme in the prior art, and to provide a fast, non-invasive and non-contact technology for measuring the rigidity and elasticity of hydrogels.

[0006] To achieve the above objectives, the present invention provides a non-contact hydrogel mixture elastic property measurement system, comprising:

[0007] A pressure module, used for applying ultrasonic pressure to the hydrogel without contact;

[0008] an illumination module configured to provide a terahertz radiation illumination beam;

[0009] an optical module disposed in an optical path of the illumination module for forwarding and directing at least a portion of the terahertz radiation illumination beam onto the hydrogel of the subject and receiving at least a portion of the terahertz radiation reflected from the hydrogel to provide a beam of return terahertz radiation;

[0010] a terahertz detection module configured to provide a detection signal by detecting the returned terahertz radiation;

[0011] A signal processing module is configured to communicate with the terahertz detection module to receive the detection signal and process the detection signal through an analysis algorithm to provide a measurement value of the elasticity and stiffness of the hydrogel of the subject.

[0012] As a further preferred technical solution of the above technical solution, the measurement method of the non-contact hydrogel mixture elastic property measurement system is specifically implemented by the following steps:

[0013] Step S1: projecting a terahertz signal onto the surface of the hydrogel through an illumination module;

[0014] Step S2: measuring the terahertz reflectance / transmittance of the hydrogel by a terahertz detection module to generate first information and transmit the first information to the signal processing module;

[0015] Step S3: projecting ultrasonic pressure on the surface of the hydrogel through a pressure module;

[0016] Step S4: measuring the terahertz reflectance / transmittance of the hydrogel by a terahertz detection module to generate second information and transmitting the second information to the signal processing module;

[0017] Step S5: The signal processing module calculates the elastic characteristic parameters of the hydrogel to be tested according to the first information and the second information.

[0018] As a further preferred technical solution of the above technical solution, the processing of the signal processing module is:

[0019] When the hydrogel to be tested is in a plane stress state, the refractive index change ΔN is expressed by the stress parameter:

[0020] ΔN=c(δ1-δ'1) / 2πfd=cΔδs / 2πfd;

[0021] Wherein, Δδs is the phase delay change of the terahertz pulse caused by stress (δ1 is the application of ultrasonic pressure, δ'1 is the application of no ultrasonic pressure), f is the frequency of terahertz radiation, c is the speed of light in vacuum, and d is the original thickness of the hydrogel;

[0022] The phase delay factor of the terahertz pulse includes the refractive index change caused by the photoelastic law and the thickness change caused by the Poisson effect. The phase delay is further extended to include both the delay Δδd caused by thickness and the delay Δδs caused by stress. The expression is:

[0023] Δδ=Δδs+Δδd;

[0024] It is known that the thickness of the hydrogel changes under stress, expressed as: Δd = dμσ / E;

[0025] Where μ, σ and E are Poisson’s ratio, internal tensile stress and elastic modulus, respectively. The change in thickness is observed from the time domain spectrum. Assuming that the initial refractive index of the hydrogel is N0, the phase change of Δδd caused by the thickness reduction can be expressed as: Δδd = 2πf(N0-1)Δd / c;

[0026] Therefore, the stress-induced phase transformation is further modified to:

[0027] ΔN=cΔδs / 2πfd+(N0-1)μσ / E;

[0028] From the terahertz time-domain spectrum, the phase delay and the change of the refractive index are obtained, and the elastic modulus E is extracted.

[0029] As a further preferred technical solution of the above technical solution, the terahertz detection module is used to receive the terahertz signal passing through the hydrogel before and after the sound pressure is applied to the surface of the hydrogel.

[0030] As a further preferred technical solution of the above technical solution, the terahertz radiation illumination beam is perpendicular to the hydrogel.

[0031] The beneficial effects of the present invention are:

[0032] The present invention provides a rapid and reliable hydrogel mixture analysis system for use in milk and the like, based on the scattering of at least two different wavelengths of light by a milk sample. The analysis includes identifying the type of milk, measuring milk components such as fat and protein, and detecting possible adulteration and spoilage. The technique requires only a low-power laser to be projected into the milk sample while a light-sensitive sensor measures the scattered light. Due to the ease of system setup and operation, the present invention could replace existing chemical analysis, ultrasound, and even other optical techniques.

[0033] In addition, this technology can also be used to extract and measure relevant parameters such as the elasticity of the human cornea. Compared with traditional methods, this method can avoid contact with the patient's cornea and has no radiation damage to the cornea. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of the present invention.

[0035] Figure 2 It is a graph showing the change of THz signal when ultrasonic signals of different amplitudes are applied to the hydrogel sample.

[0036] Figure 3 is the measurement results of hydrogel samples at different hydration levels.

[0037] Figure 4 is a schematic diagram in transmission mode.

[0038] Figure 5is a schematic diagram of a phased array air-coupled transducer.

[0039] Figure 6 This is a schematic diagram of using pulsed laser to generate ultrasonic pressure. DETAILED DESCRIPTION

[0040] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0041] In the preferred embodiments of the present invention, those skilled in the art should note that the hydrogels and the like involved in the present invention may be regarded as prior art.

[0042] Preferred embodiments.

[0043] like Figure 1-6 As shown, the present invention discloses a non-contact hydrogel mixture elastic property measurement system, which is characterized by comprising:

[0044] A pressure module, used for applying ultrasonic pressure to the hydrogel without contact;

[0045] an illumination module configured to provide a terahertz radiation illumination beam;

[0046] an optical module disposed in an optical path of the illumination module for forwarding and directing at least a portion of the terahertz radiation illumination beam onto the hydrogel of the subject and receiving at least a portion of the terahertz radiation reflected from the hydrogel to provide a beam of return terahertz radiation;

[0047] a terahertz detection module configured to provide a detection signal by detecting the returned terahertz radiation;

[0048] A signal processing module is configured to communicate with the terahertz detection module to receive the detection signal and process the detection signal through an analysis algorithm to provide a measurement value of the elasticity and stiffness of the hydrogel of the subject.

[0049] Specifically, the measurement method of the non-contact hydrogel mixture elastic property measurement system is specifically implemented by the following steps:

[0050] Step S1: projecting a terahertz signal onto the surface of the hydrogel through an illumination module;

[0051] Step S2: measuring the terahertz reflectance / transmittance of the hydrogel by a terahertz detection module to generate first information and transmit the first information to the signal processing module;

[0052] Step S3: projecting ultrasonic pressure on the surface of the hydrogel through a pressure module;

[0053] Step S4: measuring the terahertz reflectance / transmittance of the hydrogel by a terahertz detection module to generate second information and transmitting the second information to the signal processing module;

[0054] Step S5: The signal processing module calculates the elastic characteristic parameters of the hydrogel to be tested according to the first information and the second information.

[0055] More specifically, the signal processing module processes:

[0056] When the hydrogel to be tested is in a plane stress state, the refractive index change ΔN is expressed by the stress parameter:

[0057] ΔN=c(δ1-δ'1) / 2πfd=cΔδs / 2πfd;

[0058] Wherein, Δδs is the phase delay change of the terahertz pulse caused by stress (δ1 is the application of ultrasonic pressure, δ'1 is the application of no ultrasonic pressure), f is the frequency of terahertz radiation, c is the speed of light in vacuum, and d is the original thickness of the hydrogel;

[0059] The phase delay factor of the terahertz pulse includes the refractive index change caused by the photoelastic law and the thickness change caused by the Poisson effect. The phase delay is further extended to include both the delay Δδd caused by thickness and the delay Δδs caused by stress. The expression is:

[0060] Δδ=Δδs+Δδd;

[0061] It is known that the thickness of the hydrogel changes under stress, expressed as: Δd = dμσ / E;

[0062] Where μ, σ and E are Poisson’s ratio, internal tensile stress and elastic modulus, respectively. The change in thickness is observed from the time domain spectrum. Assuming that the initial refractive index of the hydrogel is N0, the phase change of Δδd caused by the thickness reduction can be expressed as: Δδd = 2πf(N0-1)Δd / c;

[0063] Therefore, the stress-induced phase transformation is further modified to:

[0064] ΔN=cΔδs / 2πfd+(N0-1)μσ / E;

[0065] From the terahertz time-domain spectrum, the phase delay and the change of the refractive index are obtained, and the elastic modulus E is extracted.

[0066] Furthermore, the terahertz detection module is used to receive the terahertz signal passing through the hydrogel before and after the sound pressure is applied to the surface of the hydrogel.

[0067] Furthermore, the terahertz radiation illumination beam is perpendicular to the hydrogel.

[0068] The pressure module is an air-coupled ultrasonic transducer that provides acoustic pressure to the hydrogel, and the terahertz detection module is used to receive the terahertz signal passing through the hydrogel sample before and after the acoustic pressure is applied to the hydrogel surface.

[0069] Figure 2 The figure shows the change of THz signal when ultrasonic signals of different amplitudes are applied to the hydrogel sample. The ultrasonic intensity generated by the air-coupled ultrasonic transducer is proportional to the applied voltage.

[0070] like Figure 3 As shown in Figure 2, the time delay of the terahertz signal increases monotonically with the increase of the ultrasound intensity applied to the hydrogel sample. The time delay at different ultrasound pressure levels can be used to calculate the elastic properties of the hydrogel.

[0071] One application of the present invention is to monitor the changes in elastic properties of hydrogels due to changes in hydration level over time. In clinical practice, it is also of interest to know the hydration level of soft tissues (such as the cornea) at different days and times. Figure 3 The results of the measurements of hydrogel samples at different hydration levels are shown. The hydrogel samples were placed in air and dehydrated at high temperature.

[0072] Table 1 lists the mass, thickness, and relative hydration level over time. Measurements were made at different times corresponding to different hydration levels. Figure 3 As shown, the changes in the THz frequency are closely related to the changes in the hydration level. Therefore, it is feasible to use this technique to non-contactly monitor the changes in elastic properties caused by changes in hydration level.

[0073] Table 1 Mass, thickness and relative hydration level of hydrogel samples dehydrated over time

[0074]

[0075] In another preferred embodiment, the THz measurement can be performed in transmission mode, that is, the THz transmitter is located on the same side of the ultrasonic transducer, while the THz detector is located on the other side of the hydrogel sample.

[0076] like Figure 4 As shown, the terahertz beam is substantially perpendicular to the hydrogel sample, which can achieve maximum terahertz sensitivity. To facilitate the transmission of the terahertz signal, the air-coupled transducer may have a cavity in the center for the terahertz signal to pass through.

[0077] like Figure 5 As shown. The array of air-coupled transducers can be configured in one-dimensional or two-dimensional arrangement to generate controllable ultrasonic waves at any spatial position of the hydrogel sample. The position of the terahertz measurement should coincide with the focus of the phased array air-coupled transducer. The air-coupled two-dimensional phased array transducer can be made of capacitive micromachined ultrasonic transducer (CMUT), piezoelectric micromachined ultrasonic transducer (PMUT) or other transducer manufacturing methods.

[0078] Ultrasonic pressure can also be generated by pulsed lasers, such as Figure 6 As shown. The pulsed laser can be a nanosecond laser, a picosecond laser, or a femtosecond laser. The laser light can be diffused to a considerable area of ​​the hydrogel sample.

[0079] For the present invention:

[0080] Ultrasonic pressure is applied to the hydrogel and detected in the terahertz range of the electromagnetic spectrum between microwave and infrared frequencies, typically ranging from 100 GHz (1011 Hz, wavelength 3 mm) to 10 THz (1013 Hz, wavelength 3.3 microns). The elasticity and stiffness of the hydrogel in vivo and in vitro are measured using ultrasonic pressure and terahertz time-domain spectroscopy and / or a designed terahertz portable system.

[0081] The terahertz detection module picks up the terahertz signal difference between the hydrogel with and without ultrasonic stress measured by the terahertz detector, thereby deriving the rigidity and elastic parameters of the hydrogel. More specifically, the measurement of the elastic parameters is based on a set of calibration equations related to the terahertz signal difference between the stressed and unstressed hydrogels. The calibration equations can be modeled by fitting the terahertz signal difference with the data of the actual hydrogel elasticity.

[0082] The advantages of the present invention are:

[0083] The system changes the detection method of the hydrogel mixture from contact to non-contact, and measures the rigidity and elasticity of the hydrogel quickly, non-invasively and non-contactly. Due to the simple system setup and operation, the present invention can replace the existing chemical analysis, ultrasound and even other optical technologies. The technology can also be used to extract and measure relevant parameters such as the elasticity of the human cornea. Compared with traditional methods, this method can avoid contact with the patient's cornea and has no radiation damage to the cornea.

[0084] It is worth mentioning that the technical features such as hydrogels involved in the patent application of the present invention should be regarded as prior art. The specific structure, working principle and possible control method and spatial arrangement method of these technical features can be selected by conventional methods in the field and should not be regarded as the inventive point of the present patent. The present patent will not be further elaborated.

[0085] For those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-contact hydrogel mixture elastic property measurement system, characterized in that: include: A pressure module, used for applying ultrasonic pressure to the hydrogel without contact; an illumination module configured to provide a terahertz radiation illumination beam; an optical module disposed in an optical path of the illumination module for forwarding and directing at least a portion of the terahertz radiation illumination beam onto the hydrogel of the subject and receiving at least a portion of the terahertz radiation reflected from the hydrogel to provide a beam of return terahertz radiation; a terahertz detection module configured to provide a detection signal by detecting the returned terahertz radiation; A signal processing module is configured to communicate with the terahertz detection module to receive the detection signal and process the detection signal through an analysis algorithm to provide a measurement value of the elasticity and stiffness of the hydrogel of the subject.

2. A non-contact hydrogel mixture elastic property measurement system according to claim 1, characterized in that: The measurement method of the non-contact hydrogel mixture elastic property measurement system is specifically implemented by the following steps: Step S1: projecting a terahertz signal onto the surface of the hydrogel through an illumination module; Step S2: measuring the terahertz reflectance / transmittance of the hydrogel by a terahertz detection module to generate first information and transmit the first information to the signal processing module; Step S3: projecting ultrasonic pressure on the surface of the hydrogel through a pressure module; Step S4: measuring the terahertz reflectance / transmittance of the hydrogel by a terahertz detection module to generate second information and transmitting the second information to the signal processing module; Step S5: The signal processing module calculates the elastic characteristic parameters of the hydrogel to be tested according to the first information and the second information.

3. A non-contact hydrogel mixture elastic property measurement system according to claim 2, characterized in that: The signal processing module processes: When the hydrogel to be tested is in a plane stress state, the refractive index change ΔN is expressed by the stress parameter: ΔN=c(δ1-δ'1) / 2πfd=cΔδs / 2πfd; Where Δδs is the phase delay change of the terahertz pulse caused by stress, f is the frequency of terahertz radiation, c is the speed of light in vacuum, and d is the original thickness of the hydrogel; The phase delay factor of the terahertz pulse includes the refractive index change caused by the photoelastic law and the thickness change caused by the Poisson effect. The phase delay is further extended to include both the delay Δδd caused by thickness and the delay Δδs caused by stress. The expression is: Δδ=Δδs+Δδd; It is known that the thickness of the hydrogel changes under stress, expressed as: Δd = dμσ / E; Where μ, σ and E are Poisson’s ratio, internal tensile stress and elastic modulus, respectively. The change in thickness is observed from the time domain spectrum. Assuming that the initial refractive index of the hydrogel is N0, the phase change of Δδd caused by the thickness reduction can be expressed as: Δδd = 2πf(N0-1)Δd / c; Therefore, the stress-induced phase transformation is further modified to: ΔN=cΔδs / 2πfd+(N0-1)μσ / E; From the terahertz time-domain spectrum, the phase delay and the change of the refractive index are obtained, and the elastic modulus E is extracted.

4. A non-contact hydrogel mixture elastic property measurement system according to claim 1, characterized in that: The terahertz detection module is used to receive the terahertz signal passing through the hydrogel before and after the sound pressure is applied on the surface of the hydrogel.

5. The non-contact hydrogel mixture elastic property measurement system according to claim 1, characterized in that: The terahertz radiation illumination beam is perpendicular to the hydrogel.

Images