Silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor

Abstract

The present application discloses a silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor, which relates to the technical field of sensor chips. The sensor comprises: a sensor oscillation circuit, which comprises a parallel resonant branch and a negative resistance generating branch; the parallel resonant branch comprises a near-field sensing capacitor and two inductors L, and the two ends of the near-field sensing capacitor are each connected to a positive power supply V through one of the inductors L. DD The negative resistance generating branch and the two inductors L are far away from the positive power supply V DD At the same time, if the near-field sensing capacitor is in a detection state, the sensing oscillation circuit is configured to generate a corresponding oscillation frequency according to different objects to be tested, so as to determine the dielectric constant at the current oscillation frequency. The present application has the characteristics of large output swing, low power consumption, simple design, low cost and small size.

Description

Technical Field

[0001] The present application relates to the technical field of sensor chips, and in particular to a silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor. Background Art

[0002] In biological and medical diagnosis, lab-on-chip systems are often used for detection and sensing, and lab-on-chip systems also rely on optical measurement technology. Although optical measurement technology can provide relatively accurate visual results, the measurement system in optical measurement technology is mainly composed of bulky optical equipment and test benches, which makes it difficult to truly achieve the goal of miniaturization design in biomedical instant detection. At the same time, optical measurement technology also requires biological labeling, that is, fluorescent labeling, and these labels have the risk of changing the properties of the materials to be tested. Summary of the invention

[0003] In order to solve at least one of the above-mentioned technical problems, an embodiment of the present application provides a silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor.

[0004] The present application embodiment provides a silicon-based near-field millimeter wave biomedical dielectric oscillation sensor, which is integrated with:

[0005] A sensing oscillation circuit, comprising a parallel resonant branch and a negative resistance generating branch;

[0006] The parallel resonant branch includes a near-field sensing capacitor and two inductors L. The two ends of the near-field sensing capacitor are each connected to a positive power supply V through an inductor L. DD ;

[0007] The negative resistance generating branch and the two inductors L are far away from the positive power supply V DD At the same time,

[0008] If the near-field sensing capacitor is in a detection state, the sensing oscillation circuit is configured to generate corresponding oscillation frequencies according to different objects to be tested, so as to determine the dielectric constant at the current oscillation frequency.

[0009] In some embodiments, the near-field sensing capacitor includes a strip-shaped near-field sensing capacitor.

[0010] In some embodiments, the strip-shaped near-field sensing capacitor includes:

[0011] Two comb-tooth-shaped conductors, each comb tooth on one conductor extends into the gap between each comb tooth on the other conductor, so that any two adjacent comb teeth form a unit sensing capacitor.

[0012] In some embodiments, the unit sensing capacitor includes a substrate layer and an oxide layer on the substrate layer, and a metal electrode is etched in the oxide layer.

[0013] In some embodiments, the negative resistance generating branch includes a transistor M1, a transistor M2 and a transistor M3, and two inductors L are defined as a first inductor L1 and a second inductor L2 respectively; wherein,

[0014] The drain of the transistor M1 and the first inductor L1 are far away from the positive power supply V DD One end of the transistor M2 is connected to the gate, and the gate is connected to the drain of the transistor M2;

[0015] The drain of the transistor M2 and the second inductor L2 are also far away from the positive power supply V DD One end of the transistor M1 is connected to the gate, and the gate is connected to the drain of the transistor M1;

[0016] The drain of the transistor M3 is connected to the source of the transistor M1 and the source of the transistor M2, and the gate is connected to the bias voltage V b , the source is grounded.

[0017] In some embodiments, the sensor is further integrated with:

[0018] The buffer circuit is arranged at both ends of the near-field sensing capacitor and is configured to buffer and output the oscillation frequency generated by the sensing oscillation circuit.

[0019] In some embodiments, the buffer circuit includes two buffer branches, one of the buffer branches includes a transistor M4, a resistor R1 and a capacitor C1, and the other buffer branch includes a transistor M5, a resistor R2 and a capacitor C2;

[0020] The gate of the transistor M4 is connected to the drain of the transistor M1, and the drain is connected to the positive power supply V DD , the source is grounded through the resistor R1, one end of the capacitor C1 is connected to the end of the resistor R1 away from the ground, and the other end is configured as an output end;

[0021] The gate of the transistor M5 is connected to the drain of the transistor M2, and the drain is connected to the positive power supply V DD , the source is grounded through the resistor R3, one end of the capacitor C3 is connected to the end of the resistor R3 away from the ground, and the other end is configured as another output end.

[0022] In some embodiments, if the near-field sensing capacitor is a strip-shaped near-field sensing capacitor, the mathematical relationship between the dielectric constant and the oscillation frequency of the object to be measured satisfies:

[0023]

[0024]

[0025] In the formula, ε MUT is the dielectric constant of the object to be measured, ε sub is the dielectric constant of the substrate layer,

[0026] ε0 is the absolute dielectric constant, K(k) is the solution of the infinite elliptic integral, and the integral depends on the geometry of the near-field sensing capacitor, C ox is the capacitance of the oxide layer, l is the strip length, N is the total number of comb teeth in the near-field sensing capacitor, and L 1，2 is the sum of the inductance of the first inductor L1 and the second inductor L2, C total It is the sum of the capacitance of the near-field sensing capacitor and the parasitic capacitance generated by the transistors M1 to M5.

[0027] In some embodiments, the transistor M1, the transistor M2 and the transistor M3 are all NMOS transistors; or,

[0028] The transistor M4 and the transistor M5 are both NMOS transistors.

[0029] In some embodiments, the sensor is used to detect an object to be detected with a dielectric constant of 0.1-20.

[0030] The beneficial effects brought about by the technical solution provided in this application include: integrating microelectronic circuits into sensors to truly realize miniaturized design in biomedical point of care testing (POCT), improving the sensitivity and accuracy of point-of-care testing, reducing volume and cost, and being used for non-destructive and label-free biomedical point-of-care testing and characterization, that is, having the characteristics of high sensitivity, high accuracy, label-free, non-destructive, miniature portability and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A schematic diagram of a silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor provided in an embodiment of the present application;

[0033] Figure 2 is a schematic diagram of a unit sensing capacitor in a strip near-field sensing capacitor;

[0034] Figure 3 is the circuit diagram of the buffer circuit;

[0035] Figure 4 A schematic diagram of another silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor provided in an embodiment of the present application;

[0036] Figure 5 is the capacitance C of the near-field sensing capacitor when the sensor is fully covered with dielectric solutions of different dielectric constants S and dielectric constant ε MUT The relationship curve between

[0037] Figure 6 is a waveform diagram of the oscillation frequency of the output when the sensor is not covered with the medium solution;

[0038] Figure 7 is the oscillation frequency f and dielectric constant ε when the sensor is fully covered with dielectric solutions of different dielectric constants MUT The relationship curve between them.

[0039] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0041] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may also be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0042] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0043] like Figure 1 As shown, the embodiment of the present application provides a silicon-based near-field millimeter wave biomedical dielectric oscillation sensor, which is integrated with:

[0044] A sensing oscillation circuit, comprising a parallel resonant branch and a negative resistance generating branch;

[0045] The parallel resonant branch includes a near-field sensing capacitor and two inductors L. The two ends of the near-field sensing capacitor are each connected to a positive power supply V through an inductor L. DD ;

[0046] The negative resistance generating branch and the two inductors L are far away from the positive power supply V DD At the same time,

[0047] If the near-field sensing capacitor is in a detection state, the sensing oscillation circuit is configured to generate corresponding oscillation frequencies according to different objects to be tested, so as to determine the dielectric constant at the current oscillation frequency.

[0048] In the embodiment of the present application, a sensor oscillation circuit is integrated on the sensor to form an integrated near-field millimeter wave biosensor chip with both sensing and signal processing capabilities. Among them, the near-field millimeter wave biosensor refers to the detection when the distance between the biological material to be tested and the sensor is very close (the distance from the biological target to the sensor is less than the wavelength of the sensor), ensuring high sensitivity.

[0049] When using sensors to detect different objects to be tested, the near-field sensing capacitor detects the object to be tested (biological solution or material) whose dielectric constant changes with water content through its near electric field, responds with different capacitance values, and combines with inductor resonance, and then drives the branch through negative resistance to generate a large-amplitude millimeter-wave oscillation frequency signal to drive the subsequent signal processing circuit. It can be seen that different objects to be tested correspond to different capacitance values, and different capacitance values ​​correspond to a unique oscillation frequency. Therefore, after determining the oscillation frequency, the capacitance can be further determined, and then the dielectric constant can be further determined to determine the object to be tested.

[0050] The negative resistance generating branch is connected to the parallel resonant branch and offsets the parasitic resistance generated by the parallel resonant branch.

[0051] The embodiment of the present invention is based on a standard silicon-based CMOS process, and fully integrates the near-field capacitance sensing structure and the signal generation / output circuit, which can improve the sensitivity. At the same time, the sensor has the characteristics of large output swing, low power consumption, simple design, low cost and small size. Therefore, it can be widely used in the field of high-sensitivity, non-destructive, label-free and portable biomedical instant detection and characterization.

[0052] As a preferred solution of the embodiment of the present application, the near-field sensing capacitor includes a strip-shaped near-field sensing capacitor.

[0053] like Figure 1 As shown, further, the strip-shaped near-field sensing capacitor includes:

[0054] Two comb-tooth-shaped conductors, each comb tooth on one conductor extends into the gap between each comb tooth on the other conductor, so that any two adjacent comb teeth form a unit sensing capacitor.

[0055] like Figure 1 As shown in FIG. 4 , the strip-shaped near-field sensing capacitor has 10 comb teeth, each conductor has five comb teeth, and any two adjacent comb teeth form a unit sensing capacitor. Therefore, in this embodiment, there are 9 unit sensing capacitors.

[0056] like Figure 2 As shown, further, the unit sensing capacitor includes a substrate layer and an oxide layer on the substrate layer, and a metal electrode is etched in the oxide layer.

[0057] In this embodiment, the unit sensing capacitor is mainly composed of a substrate layer and an oxide layer on the substrate layer. Two metal electrodes are etched in the oxide layer. Figure 2 The electrodes 1 and 2 are arranged at intervals, and biological materials to be tested with different dielectric constants are covered on the electrodes 1 and 2 to obtain different capacitances in response.

[0058] As a preferred solution of the embodiment of the present application, the negative resistance generating branch includes a transistor M1, a transistor M2 and a transistor M3, and the two inductors L are defined as a first inductor L1 and a second inductor L2 respectively; wherein,

[0059] The drain of the transistor M1 and the first inductor L1 are far away from the positive power supply V DD One end of the transistor M2 is connected to the gate, and the gate is connected to the drain of the transistor M2;

[0060] The drain of the transistor M2 and the second inductor L2 are also far away from the positive power supply V DD One end of the transistor M1 is connected to the gate, and the gate is connected to the drain of the transistor M1;

[0061] The drain of the transistor M3 is connected to the source of the transistor M1 and the source of the transistor M2, and the gate is connected to the bias voltage V b , the source is grounded.

[0062] Specifically, the transistor M1, the transistor M2 and the transistor M3 are all NMOS transistors. Based on the standard silicon-based CMOS process, the capacitive sensing structure and the signal generation / output microelectronic circuit are fully integrated, which has the characteristics of simple design, low power consumption, low cost and small size, so as to achieve the application requirements of high sensitivity, non-destructive, label-free and portable sensors required for biomedical instant detection and characterization.

[0063] In this embodiment, the near-field sensing capacitor and the first inductor L1 and the second inductor L2 form a parallel resonant branch, and the transistors M1 and M2 generate negative resistance to offset the parasitic positive resistance that causes energy loss in the parallel resonant branch, thereby driving the parallel resonant branch to oscillate and generate a differential voltage signal. After the differential voltage signal is processed, a single-ended voltage signal is obtained, such as Figure 3 As shown, the oscillation frequency is determined from the single-ended voltage signal.

[0064] As another preferred solution of the embodiment of the present application, the sensor is also integrated with:

[0065] The buffer circuit is arranged at both ends of the near-field sensing capacitor and is configured to buffer and output the oscillation frequency generated by the sensing oscillation circuit.

[0066] like Figures 3-4 As shown, further, the buffer circuit includes two buffer branches, one of the buffer branches includes a transistor M4, a resistor R1 and a capacitor C1, and the other buffer branch includes a transistor M5, a resistor R2 and a capacitor C2;

[0067] The gate of the transistor M4 is connected to the drain of the transistor M1, and the drain is connected to the positive power supply V DD , the source is grounded through the resistor R1, one end of the capacitor C1 is connected to the end of the resistor R1 away from the ground, and the other end is configured as an output end;

[0068] The gate of the transistor M5 is connected to the drain of the transistor M2, and the drain is connected to the positive power supply V DD , the source is grounded through the resistor R3, one end of the capacitor C3 is connected to the end of the resistor R3 away from the ground, and the other end is configured as another output end.

[0069] Specifically, the transistor M4 and the transistor M5 are both NMOS transistors.

[0070] like Figure 4 As shown, in a specific embodiment, a sensor oscillation circuit and a buffer circuit are integrated on the sensor.

[0071] The sensing oscillation circuit includes NMOS transistors M1, M2, M3, a first inductor L1, a second inductor L2, and a strip near-field sensing capacitor. The gate of transistor M1 is connected to the drain of transistor M2, the gate of transistor M2 is connected to the drain of transistor M1, and the drains of transistors M1 and M2 are respectively connected to the two electrodes of the sensing capacitor, and then respectively connected to the positive power supply V through the first inductor L1 and the second inductor L2. DD The sources of transistors M1 and M2 are connected to the drain of transistor M3, and the gate of transistor M3 is connected to the bias voltage V b , the source of transistor M3 is grounded.

[0072] The buffer circuit includes NMOS transistors M4 and M5, resistors R1 and R2, and capacitors C1 and C2. The gates of transistors M4 and M5 are connected to the drains of transistors M1 and M2 respectively, and the drains of transistors M4 and M5 are connected to the positive power supply V DD The sources of transistors M4 and M5 are grounded via resistors R1 and R2 respectively, and the sources of transistors M4 and M5 output differential voltage signals via capacitors C1 and C2 respectively, wherein the differential voltage signal is processed to obtain a single-ended voltage signal, and the oscillation frequency f is determined from the processed voltage signal.

[0073] Preferably, if the near-field sensing capacitor is a strip-shaped near-field sensing capacitor, the mathematical relationship between the dielectric constant and the oscillation frequency of the object to be measured satisfies:

[0074]

[0075]

[0076] In the formula, ε MUT is the dielectric constant of the object to be measured, ε sub is the dielectric constant of the substrate layer,

[0077] ε0 is the absolute dielectric constant, K(k) is the solution of the infinite elliptic integral, and the integral depends on the geometry of the near-field sensing capacitor, C ox is the capacitance of the oxide layer, l is the strip length, N is the total number of comb teeth in the near-field sensing capacitor, and L 1，2 is the sum of the inductance of the first inductor L1 and the second inductor L2, C total It is the sum of the capacitance of the near-field sensing capacitor and the parasitic capacitance generated by the transistors M1 to M5.

[0078] The silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor provided in the embodiment of the present application is described in detail below in conjunction with a specific embodiment.

[0079] like Figure 2 As shown in FIG. 1 , it is a schematic diagram of a unit sensing capacitor, in which the electrode 1 and the electrode 2 (represented in black and white, respectively) are formed by the low-loss top metal layer in the standard silicon-based CMOS process, wherein the unit sensing capacitor includes a substrate layer, on which an oxide layer is provided, and each oxide layer is etched with a metal electrode, and the two metal electrodes are connected to the drain of the transistor M1 and the transistor M2, respectively. The material under test (MUT, biological medium solution or material) based on the change of water content is placed above the unit sensing capacitor, then the capacitance C of the unit sensing capacitor per unit length S,CELL / UNIT It can be expressed as:

[0080] CS，CELL / UNIT =C ox +C sub +C MUT ,

[0081] In the formula, C sub is the capacitance of the edge near field formed between the near field sensing capacitor and the substrate layer, C MUT is the capacitance of the edge near field formed between the near field sensing capacitor and the object to be measured, C ox is the capacitance of the oxide layer.

[0082] Among them, the capacitance C of the edge near field formed between the near field sensing capacitor and the substrate layer sub The capacitance C of the fringe near field formed between the DUT and the DUT MUT It is given by the following formula:

[0083]

[0084] In the formula, ε MUT is the dielectric constant of the object to be measured, ε sub is the dielectric constant of the substrate layer,

[0085] ε0 is the absolute dielectric constant, K(k) is the solution of the infinite elliptic integral, and the integral depends on the geometry of the near-field sensing capacitor, C sub is the capacitance of the edge near field formed between the near field sensing capacitor and the substrate layer, C MUT It is the capacitance of the edge near field formed between the near-field sensing capacitor and the object under test.

[0086] Assuming that the strip length of the strip near-field sensing capacitor is l, the capacitance of the entire strip near-field sensing capacitor is given by the following formula:

[0087] C S =l·(N-1)·C S，CELL / UNIT ,

[0088] Where, for the given strip structure of the sensor, N is the total number of comb teeth in the near-field sensing capacitor, C ox and C sub is effectively constant, so C MUT is considered as the only variable, C MUT Depends on the dielectric constant ε of the object under test (MUT) MUT From the above formulas, we can know that the entire strip near-field sensor capacitance and the dielectric constant ε of the object to be measured MUT A positively correlated relationship.

[0089] like Figure 5 As shown, it is the capacitance C of the near-field sensing capacitor when the biomedical dielectric oscillation sensor is fully covered with dielectric solutions of different dielectric constants. S and dielectric constant εMUT As can be seen from the figure, as the dielectric constant ε MUT The increase (ε MUT =0.1~80), the capacitance C of the near-field sensing capacitor S is also increasing. When the dielectric constant ε MUT When it is 0.1, the corresponding C S The minimum is 74fF.

[0090] Considering the capacitance C of the near-field sensing capacitor S and dielectric constant ε MUT The relationship curve between Figure 1 The entire strip near-field sensing capacitor and the first inductor L1 and the second inductor L2 form a parallel resonant branch. The capacitance value of the strip near-field sensing capacitor corresponds to different objects to be measured. The transistors M1 and M2 in the negative resistance generating branch generate negative resistance to offset the parasitic positive resistance that causes energy loss in the parallel resonant branch, thereby driving the parallel resonant branch to oscillate and generate a millimeter-wave band oscillation output oscillation frequency with low phase noise. The oscillation frequency f can be expressed as:

[0091]

[0092] In the formula, C S is the capacitance of the near-field sensing capacitor, L 1，2 is the sum of the inductance of the first inductor L1 and the second inductor L2, C total It is the sum of the capacitance of the near-field sensing capacitor and the parasitic capacitance generated by the transistors M1 to M5.

[0093] Obviously, the oscillation frequency f is related to the dielectric constant ε of the object under test. MUT is inversely related, that is, as ε MUT When the object to be tested (MUT, biological medium solution or material) with varying water content is placed above all the strip near-field sensing capacitors, the edge near electric field of the strip near-field sensing capacitor will change with the change of the different dielectric constants of the object to be tested, and the capacitance C of the near-field sensing capacitor will change accordingly. S According to the formula for expressing the oscillation frequency f, the oscillation frequency of the millimeter wave band oscillation output will be offset. Therefore, the dielectric constant ε of the object under test detected by the near-field sensor capacitor is MUT It is essentially the dielectric constant at the oscillation frequency f.

[0094] like Figure 6 It shows that there is no dielectric solution covering the near-field sensing capacitor (ε MUT =0.1). It can be seen that the oscillation frequency of the output single-ended voltage signal is 26.7 GHz, and the peak-to-peak voltage swing Vpp is 950 mV.

[0095] like Figure 7 As shown, the oscillation frequency f and dielectric constant ε when the near-field sensing capacitor is fully covered with dielectric solutions of different dielectric constants MUT It is obvious that the sensitivity is highest in the range of (0.1~20), which is approximately 110.6MHz / permittivity, showing a high sensitivity characteristic.

[0096] As a preferred solution of the embodiment of the present application, the sensor is used to detect an object to be detected with a dielectric constant of 0.1 to 20. When the dielectric constant is 0.1 to 20, the sensor has high sensitivity.

[0097] In summary, the dielectric oscillation sensor provided by the embodiment of the present invention is based on a standard silicon-based CMOS process, and fully integrates the near-field capacitance sensing structure and the signal generation / output circuit, thereby improving the sensitivity. Figure 7 As shown, the dielectric constant ε MUT Different dielectric solutions in the range of (0.1-20), (20-40), (40-60), (60-80) etc. all show high sensitivity, especially in the range of (0.1-20) where the oscillation frequency in the millimeter wave band is more sensitive. At the same time, the sensor has the characteristics of large output swing, low power consumption, simple design, low cost and small size. Therefore, it can be widely used in the field of high-sensitivity, non-destructive, label-free and portable biomedical instant detection and characterization.

[0098] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0099] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0100] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor, characterized in that: The sensor is integrated with: A sensing oscillation circuit, comprising a parallel resonant branch and a negative resistance generating branch; The parallel resonant branch includes a near-field sensing capacitor and two inductors L. The two ends of the near-field sensing capacitor are each connected to a positive power supply V through an inductor L. DD ; The negative resistance generating branch and the two inductors L are far away from the positive power supply V DD At the same time, If the near-field sensing capacitor is in a detection state, the sensing oscillation circuit is configured to generate corresponding oscillation frequencies according to different objects to be tested, so as to determine the dielectric constant at the current oscillation frequency; The near-field sensing capacitor comprises a strip-shaped near-field sensing capacitor; The strip-shaped near-field sensing capacitor comprises: Two comb-tooth-shaped conductors, each comb tooth on one conductor extends into the gap between each comb tooth on the other conductor, so that any two adjacent comb teeth form a unit sensing capacitor; The unit sensing capacitor comprises a substrate layer and an oxide layer on the substrate layer, wherein a metal electrode is etched in the oxide layer; If the near-field sensing capacitor is a strip-shaped near-field sensing capacitor, the mathematical relationship between the dielectric constant and the oscillation frequency of the object to be measured satisfies: In the formula, ε MUT is the dielectric constant of the object to be measured, ε sub is the dielectric constant of the substrate layer, ε0 is the absolute dielectric constant, K(k) is the solution of an infinite elliptic integral that depends on the geometry of the near-field sensing capacitor, C ox is the capacitance of the oxide layer, l is the strip length, N is the total number of comb teeth in the near-field sensing capacitor, and L 1，2 is the sum of the inductance of the first inductor L1 and the second inductor L2, C total It is the sum of the capacitance of the near field sensing capacitor and the parasitic capacitance generated by the transistor.

2. The silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor according to claim 1, characterized in that: The negative resistance generating branch includes a transistor M1, a transistor M2 and a transistor M3, and the two inductors L are defined as a first inductor L1 and a second inductor L2 respectively; wherein, The drain of the transistor M1 and the first inductor L1 are far away from the positive power supply V DD One end of the transistor M2 is connected to the gate, and the gate is connected to the drain of the transistor M2; The drain of the transistor M2 and the second inductor L2 are also far away from the positive power supply V DD One end of the transistor M1 is connected to the gate, and the gate is connected to the drain of the transistor M1; The drain of the transistor M3 is connected to the source of the transistor M1 and the source of the transistor M2, and the gate is connected to the bias voltage V b , the source is grounded.

3. The silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor according to claim 2, characterized in that: The sensor is also integrated with: The buffer circuit is arranged at both ends of the near-field sensing capacitor and is configured to buffer and output the oscillation frequency generated by the sensing oscillation circuit.

4. The silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor according to claim 3, characterized in that: The buffer circuit includes two buffer branches, one of which includes a transistor M4, a resistor R1 and a capacitor C1, and the other of which includes a transistor M5, a resistor R2 and a capacitor C2; The gate of the transistor M4 is connected to the drain of the transistor M1, and the drain is connected to the positive power supply V DD , the source is grounded through the resistor R1, one end of the capacitor C1 is connected to the end of the resistor R1 away from the ground, and the other end is configured as an output end; The gate of the transistor M5 is connected to the drain of the transistor M2, and the drain is connected to the positive power supply V DD , the source is grounded through the resistor R2, one end of the capacitor C2 is connected to the end of the resistor R2 away from the ground, and the other end is configured as another output end.

5. The silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor according to claim 4, characterized in that: The transistor M1, the transistor M2 and the transistor M3 are all NMOS transistors; or, The transistor M4 and the transistor M5 are both NMOS transistors.

6. The silicon-based near-field millimeter-wave biomedical dielectric oscillation sensor according to any one of claims 1 to 5, characterized in that: The sensor is used to detect an object to be tested with a dielectric constant of 0.1-20.

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