Gingival crevicular fluid sampling and quantifying device and method based on capacitance value change of parallel-plate capacitor
By measuring the change in the dielectric constant of a liquid using a parallel-plate capacitor, the relationship between capacitance and liquid volume is established. This solves the problems of accuracy and operational complexity in the quantitative measurement of gingival crevicular fluid, enabling rapid and accurate quantitative measurement of gingival crevicular fluid, which is suitable for the diagnosis of periodontitis.
Patent Information
- Application Number
- CN202511854327.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-10
- Publication Date
- 2026-01-16
AI Technical Summary
Existing methods for quantifying gingival crevicular fluid have problems such as affecting subsequent biomarker detection, high accuracy requirements, high cost, complex operation, and sample evaporation, making it difficult to achieve rapid and accurate quantification of gingival crevicular fluid.
A quantitative sampling device for gingival crevicular fluid based on the capacitance change of a parallel plate capacitor was adopted. By measuring the change in the dielectric constant of the liquid, a standard curve between the capacitance value and the liquid volume was established, and a precision capacitance meter was used to achieve rapid and accurate quantification of gingival crevicular fluid.
It achieves high-precision, low-cost, and non-destructive quantification of gingival crevicular fluid, is easy to operate, is suitable for batch clinical testing, has a correlation of up to 95%, and meets clinical diagnostic criteria.
Smart Images
Figure CN121337404A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of periodontitis detection technology, and in particular to a quantitative device and method for gingival crevicular fluid sampling based on the capacitance change of a parallel plate capacitor. Background Technology
[0002] Periodontitis, a prevalent chronic disease worldwide, is the sixth most common periodontal disease globally. Gingival crevicular fluid (GCF) is of significant value in the diagnosis of periodontitis due to its non-invasive sampling and ability to accurately reflect the location of periodontal lesions. The amount of GCF secretion can serve as an indicator of the severity of periodontitis to some extent, and multiple studies have shown that the relationship between GCF volume and gingival inflammation has potential clinical value. In healthy tissue, the amount of GCF is lower, while in inflamed tissue, the amount is higher, and this change may show a linear relationship with the degree of inflammation. Furthermore, many studies have explored the association between other inflammatory markers and GCF volume. For example, there is a significant correlation between the gingival index and GCF volume; the higher the gingival index, the greater the GCF volume. In pathological examination, the density of inflammatory cells also shows a good correlation with GCF measurements; and the flow rate of GCF increases with increasing periodontal pocket depth. All these findings indicate that measuring the volume of GCF has significant clinical value in assessing the state of periodontitis. However, the ninhydrin staining method in existing quantitative methods for gingival crevicular fluid may affect the subsequent detection of biomarkers. Journal of clinical periodontology ,11(10), 652–661.), Although the gravimetric method is compatible with all gingival crevicular fluid collection methods, it requires high precision of the balance and is subject to sample evaporation. Although the Periotron can accurately quantify gingival crevicular fluid, it is expensive and only compatible with the Periopaper as a sampling tool. IJMDAT (4, e364), while Periodopaper, as a gingival crevicular fluid sampling tool, has slow sampling, complex elution, and poor protein recovery rate. Summary of the Invention
[0003] To overcome the problems existing in the prior art, the present invention aims to propose a quantitative device and method for sampling gingival crevicular fluid based on the capacitance change of a parallel-plate capacitor. This method utilizes the property that the dielectric constant of liquid is much greater than that of air. When the sampling brush, after absorbing the liquid, is inserted between the plates of the parallel-plate capacitor, it significantly changes the dielectric constant of the entire capacitor system, thereby causing a significant change in the capacitance value. By establishing a standard curve between the capacitance value and the liquid volume, rapid, accurate, and non-destructive measurement of trace amounts of gingival crevicular fluid can be achieved.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A quantitative sampling device for gingival crevicular fluid based on the capacitance change of a parallel plate capacitor includes: a parallel plate capacitor unit and a measuring unit, wherein the parallel plate capacitor unit includes two parallel metal plates 1 arranged opposite each other; The measuring unit includes a precision capacitance meter 4, which is electrically connected to the two metal plates 1 of the parallel plate capacitor unit via wires, and is used to measure the capacitance value between the two plates.
[0005] The metal electrode 1 is fixed parallel to each other on the insulating support 3, and the metal electrode 1 is a copper electrode block.
[0006] The distance between the two metal plates 1 is 0.5 mm to 0.6 mm.
[0007] A hydrophobic film 2 is attached to the contact surface between the metal electrode 1 and the object being tested.
[0008] The hydrophobic film 2 is made of PVC, PET, or PP film.
[0009] The thickness of the hydrophobic film 2 is 0.04-0.06 mm.
[0010] The insulating support 3 is made of polylactic acid or resin through 3D printing.
[0011] A quantitative method based on the above-mentioned gingival crevicular fluid sampling and quantitative device, characterized by comprising the following steps: S1 Construct a parallel plate capacitor device, which includes two parallel and oppositely arranged metal plates 1, an insulating support 3 for fixing and maintaining the parallelism and spacing between the two metal plates 1, and a precision capacitance meter 4 for measuring the capacitance value. The precision capacitance meter 4 is electrically connected to the two metal plates 1 through wires. S2 Establishing a standard curve: Multiple gingival crevicular fluid sampling brushes, each containing 0.2-2.0 μL of standard liquid and increasing in increments of 0.1 μL within the 0.2-2.0 μL range, are inserted between the two metal plates 1 of the parallel plate capacitor. The capacitance value corresponding to each known volume is measured using a precision capacitance meter 4. A standard curve is plotted with the ablated volume as the x-axis and the measured capacitance value as the y-axis. The volume-capacitance relationship function is then fitted using a four-parameter logistic regression (4PL) model. Y=0.01038 + x represents the volume value, and Y represents the capacitance value; S3 Measurement of the sample to be tested: Insert the gingival crevicular fluid sampling brush, which has absorbed an unknown volume of the sample to be tested, between the two metal plates 1 of the parallel plate capacitor, and measure its capacitance value Y using a precision capacitance meter 4. S4 Quantitative Calculation: Substitute the capacitance value measured in step S3 into the volume-capacitance relationship function obtained in step S2 to calculate the volume of gingival crevice fluid sampling brush, thus realizing the quantitative calculation of the gingival crevice fluid sampling volume X.
[0012] In step S2, the standard liquid is artificial saliva or ultrapure water.
[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. High precision and high sensitivity: Based on the principle of capacitance change, this invention is extremely sensitive to changes in dielectric constant and can accurately measure the changes in trace liquids in the range of 0.2 μL to 2.0 μL. In vitro experiments show that its predicted volume has a very high correlation with the actual volume (R²>0.95).
[0014] 2. Simple and fast operation: No complicated sample processing or weighing steps are required. Simply insert the sampling brush into the measuring device, and the capacitance value can be read directly from the capacitance meter and converted into volume within seconds. It is very suitable for clinical batch testing.
[0015] 3. Non-destructive to samples: The measurement process is a physical measurement, without introducing any chemical reagents, and will not contaminate or damage the gingival crevicular fluid sample. The measured sample can be used intact for subsequent biomarker analysis (such as proteomics, inflammatory factor detection, etc.).
[0016] 4. Low cost: The core measuring device has a simple structure, mainly consisting of ordinary metal plates, brackets and general precision capacitance meters. Its cost is far lower than that of imported Periotron special equipment, which is conducive to its promotion and popularization.
[0017] 5. Strong clinical applicability: This method successfully distinguishes the differences in gingival crevicular fluid volume among healthy, gingivitis, and periodontitis patients, which is consistent with clinical diagnostic criteria, proving its practical application value.
[0018] In summary, this invention designs and constructs a parallel-plate capacitor based on copper electrodes, which alters the dielectric constant between the electrodes by drawing in different volumes of gingival crevicular fluid (GCF) using a sampling brush. This capacitor simulates the actual GCF sampling process by drawing in different volumes of artificial saliva using the sampling brush, and a standard curve was established between the volume of fluid drawn by the sampling brush and the capacitance of the parallel-plate capacitor. The sampled fluid volume can be calculated by measuring the capacitance. This method is simple and rapid, and the correlation between the actual volume and the predicted volume exceeds 95%. Preliminary clinical sample results show a significant statistical difference in GCF volume between periodontal healthy sites and mild and severe sites, a result consistent with existing research. This method provides an efficient and accurate quantitative measure for GCF sampling brushes and is suitable for chairside clinical application in GCF sampling. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the parallel plate capacitor metering device of the present invention.
[0020] Figure 2 This is a physical diagram of the parallel plate capacitor metering device of the present invention.
[0021] Figure 3 The standard curve and correlation analysis graph show the relationship between the volume and capacitance of artificial saliva in vitro.
[0022] Figure 4 A correlation analysis graph showing the relationship between the predicted volume and the actual volume of artificial saliva in vitro.
[0023] Figure 5 This is a statistical chart showing the results of detecting gingival crevicular fluid volume in clinical samples under different periodontal conditions using the method of this invention.
[0024] In the diagram, 1 is a metal electrode plate, 2 is a hydrophobic film, 3 is an insulating support, 4 is a precision capacitance meter, and 5 is a gingival crevicular fluid sampling brush. Detailed Implementation
[0025] The present invention will now be described in further detail with reference to the accompanying drawings.
[0026] See Figure 1 , Figure 2 A quantitative sampling device for gingival crevicular fluid based on the capacitance change of a parallel plate capacitor includes: a parallel plate capacitor unit and a measuring unit, wherein the parallel plate capacitor unit includes two parallel metal plates 1 arranged opposite each other and an insulating support 3 for fixing the metal plates 1. The measuring unit includes a precision capacitance meter 4, which is electrically connected to the two metal plates 1 of the parallel plate capacitor unit via wires, and is used to measure the capacitance value between the two plates.
[0027] The metal electrode plate 1 is made of copper electrode block, with dimensions of 20 mm in length, 5 mm in width, and 2 mm in height.
[0028] The distance between the two metal plates 1 is 0.5 mm to 0.6 mm.
[0029] A hydrophobic film 2 is attached to the contact surface between the metal electrode 1 and the object being tested.
[0030] The hydrophobic film 2 is made of PVC, PET, or PP film.
[0031] The thickness of the hydrophobic film 2 is 0.05 mm.
[0032] The insulating support 3 is made of polylactic acid or resin through 3D printing.
[0033] A quantitative method based on the above-mentioned gingival crevicular fluid sampling and quantitative device specifically includes the following steps: S1 Construct a parallel plate capacitor device, which includes two parallel and oppositely arranged metal plates 1, an insulating support 3 for fixing and maintaining the parallelism and spacing between the two metal plates 1, and a precision capacitance meter 4 for measuring the capacitance value. The precision capacitance meter 4 is electrically connected to the two metal plates 1 through wires. S2 Establishing a standard curve: Multiple gingival crevicular fluid sampling brushes 5, each containing 0.2-2.0 μL of artificial saliva and increasing in increments of 0.1 μL within the 0.2-2.0 μL range, are inserted between the two metal plates 1 of the parallel plate capacitor. The capacitance value corresponding to each known volume is measured using a precision capacitance meter 4. A standard curve is plotted with the aspirated volume on the x-axis and the measured capacitance value on the y-axis. The volume-capacitance relationship function is then fitted using a four-parameter logistic regression (4PL) model. Y=0.01038 + x represents the volume value, and Y represents the capacitance value; S3 Measurement of the sample to be tested: Insert the gingival crevicular fluid sampling brush 5, which has absorbed an unknown volume of the sample to be tested, between the two metal plates 1 of the parallel plate capacitor, and measure its capacitance value Y using a precision capacitance meter 4. S4 Quantitative Calculation: Substitute the capacitance value measured in step S3 into the volume-capacitance relationship function obtained in step S2 to calculate the volume of gingival crevicular fluid sampling brush 5, thus achieving quantitative calculation of the volume X of gingival crevicular fluid.
[0034] Example 1: Construction of a Quantitative Device Purchase two copper electrode blocks (size: 20 mm × 5 mm × 2 mm). Fabricate a matching polylactic acid (PLA) insulating bracket using 3D printing technology. This bracket serves to fix the two copper electrode blocks parallel and facing each other, maintaining a distance of 0.6 mm between them. Attach a 0.05 mm thick hydrophobic film (such as a PTFE film) to the facing surfaces of the two copper electrode blocks, resulting in an effective distance of 0.5 mm between the plates. Connect the two copper electrode blocks with wires, the other end of which is connected to a plug for connecting to the measurement interface of a precision capacitance meter (e.g., a TH2822 series handheld LCR meter). The schematic diagram and physical image of the assembled device are shown below. Figure 1 and Figure 2 As shown.
[0035] Example 2: Establishment of the Standard Curve The gingival crevicular fluid sampling brush 5 was used as the sampling tool. A dried gingival crevicular fluid sampling brush 5 was inserted into a parallel-plate capacitor device that was not powered on, and the capacitance meter reading was zeroed to eliminate system background error. Then, the gingival crevicular fluid sampling brush was used to accurately aspirate 0.2 μL, 0.3 μL, 0.4 μL, 0.5 μL, 0.6 μL, 0.7 μL, 0.8 μL, 0.9 μL, 1.0 μL, 1.1 μL, 1.2 μL, 1.3 μL, 1.4 μL, 1.5 μL, 1.6 μL, 1.7 μL, 1.8 μL, 1.9 μL, and 2.0 μL of artificial saliva (simulated gingival crevicular fluid), preparing 6 replicate samples for each volume gradient. After each aspiration, the gingival crevicular fluid sampling brush was sequentially inserted between the two plates of the parallel-plate capacitor, and the capacitance value of the precision capacitance meter after stabilization was read and recorded. All data were summarized, and a scatter plot was drawn with liquid volume as the independent variable X and capacitance as the dependent variable Y. A four-parameter logistic regression (4PL) model was then performed to fit the data, yielding the standard curve equation Y = 0.01038 + And calculate the coefficient of determination R². The experimental results are as follows: Figure 3 As shown, there is a strong linear positive correlation between volume and capacitance (R² = 0.9476).
[0036] Example 3: Validation of the predictive power of quantitative methods To verify the accuracy of the method, the six data points for each volume in Example 2 were randomly divided into two groups: one group (three data points) was used to establish a standard curve, and the other group (three additional data points) was used as test data. The capacitance measurements from the test dataset were substituted into the equation derived from the standard curve to calculate the predicted volume of the test data. The predicted volume was then compared and analyzed with the actual known volume of the test data, and the results were plotted. Figure 4 As shown, the predicted volume is in high agreement with the actual volume, and the correlation is very good (R² = 0.9571), indicating that the method has excellent prediction accuracy and reliability.
[0037] Example 4: Clinical Sample Testing Seven healthy volunteers, seven patients with gingivitis, seven patients with mild periodontitis, and seven patients with severe periodontitis were recruited. Gingival crevicular fluid (GCF) samples were collected from each subject using a sterile, novel GCF sampling brush. Immediately after sampling, the sampling brush was inserted into the device of this invention to measure the capacitance value, which was then converted into GCF volume (μL) according to the standard curve established in Example 2. Statistical analysis (e.g., one-way ANOVA) was performed on the GCF volume of the four groups. The results are as follows: Figure 5 As shown, the method of the present invention can effectively distinguish the differences between the healthy group and the disease group, especially the extremely significant difference between the healthy group and the severe periodontitis group (p<0.01), which is completely consistent with clinical expectations and literature reports, fully demonstrating the effectiveness and practicality of the method of the present invention in clinical practice.
[0038] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A device for quantifying the amount of gingival crevicular fluid based on the change in the capacitance of a parallel-plate capacitor, characterized in that, The parallel-plate capacitor unit comprises two metal plates (1) arranged in parallel and facing each other. The measuring unit comprises a precision capacitance meter (4) electrically connected to the two metal plates (1) of the parallel-plate capacitor unit through wires, for measuring the capacitance value between the two plates. The metal plates (1) are fixed in parallel and facing each other on an insulating support (3), and the metal plates (1) are made of copper electrode blocks.
2. The device according to claim 1, wherein The distance between the two metal plates (1) is 0.5-0.6 mm.
3. The device of claim 1, wherein, The contact surface of the metal plates (1) with the object to be detected is attached with a hydrophobic film (2).
4. The device of claim 1, wherein, The hydrophobic film (2) is made of PVC or PET or PP film.
5. The device of claim 4, wherein, The thickness of the hydrophobic film (2) is 0.04-0.06 mm.
6. The device of claim 4, wherein the device is configured to be placed on the gingival tissue of a patient and to collect a sample of the gingival crevicular fluid. The insulating support (3) is made of a polylactic acid or resin support made by 3D printing.
7. The device of claim 2, wherein, The method comprises the following steps:
8. A method of quantification based on the device for sampling of gingival crevicular fluid according to any one of claims 1 to 7, characterized in that, S1. Constructing a parallel-plate capacitor device comprising two metal plates (1) arranged in parallel and facing each other, an insulating support (3) for fixing and maintaining the parallelism and distance between the two metal plates (1), and a precision capacitance meter (4) for measuring the capacitance value, the precision capacitance meter (4) being electrically connected to the two metal plates (1) through wires; S2. Establishing a standard curve: a plurality of gingival crevicular fluid sampling brushes with 0.2-2.0 μL of standard liquid and an absorption volume in the range of 0.2-2.0 μL are inserted between the two metal plates (1) of the parallel-plate capacitor, and the capacitance values corresponding to each known volume are measured by the precision capacitance meter (4); the absorption volume is taken as the abscissa, and the measured capacitance value is taken as the ordinate, and a standard curve is drawn, and a volume-capacitance relationship function is obtained by fitting with a four-parameter logistic regression (4PL) model: x represents the volume value, and Y represents the capacitance value; Y=0.01038 + S3. Measuring the sample to be measured: a gingival crevicular fluid sampling brush with an unknown volume of gingival crevicular fluid sample to be measured is inserted between the two metal plates (1) of the parallel-plate capacitor, and the capacitance value Y is measured by the precision capacitance meter (4); S4. Quantitative calculation: the capacitance value measured in step S3 is substituted into the volume-capacitance relationship function obtained in step S2 to calculate the absorption volume of the gingival crevicular fluid sampling brush, i.e. to realize the volume quantification X of the gingival crevicular fluid sampling amount. In step S2, the standard liquid is artificial saliva or ultrapure water.
9. The method according to claim 1, wherein,