A microcantilever device for detecting a new type of tiny mass

Abstract

The present invention discloses a microcantilever device for detecting tiny mass, which includes a cantilever device, a cantilever fixed substrate, an electrode plate fixed substrate, a gasket, a gasket for adjusting electrode distance, and an electrode plate. The cantilever device is fixed on the cantilever fixed substrate through a spring clip; the electrode plate fixed substrate is provided with a gasket, and the gasket for adjusting electrode distance is provided on the gasket. The electrode plate is placed on the gasket for adjusting electrode distance and is fixed on the electrode plate fixed substrate with a spring clip. The microcantilever device for detecting tiny mass of the present invention comprises a microcantilever composed of single crystal silicon, an electrode plate device, and a tiny capacitance detection circuit. A tiny mass object acts on the microchannel inside the cantilever, causing the cantilever to deform. By detecting the capacitance change between the cantilever and the electrode plate, the mass of the tiny mass object can be calculated.

Description

Technical Field

[0001] The present invention mainly relates to the field of MEMS, and particularly to a microcantilever device for detecting a new type of tiny mass. Background Art

[0002] With the continuous development of nanotechnology, due to the small structure of MEMS devices and their mechanical responses being very sensitive to external forces, they are widely used in detection and sensor applications. The detection of tiny mass is of great significance for biological and chemical sensing and the research of some basic disciplines, such as the detection of biological macromolecules, DNA, chemical gases, pollutants, etc. Currently, several typical detection methods are: optical equipment method, electrochemical analysis method, biological detection method, micro / nano sensor detection method.

[0003] A document with the patent number 2016104117634 discloses a microcantilever device for weighing the mass of DNA molecules. It includes a microcantilever, micro displacement sensors on both the upper and lower sides of the cantilever, and a DNA molecule adsorption layer. The DNA molecule to be measured is placed on the upper surface of the DNA molecule adsorption layer near the free end of the cantilever. The cantilever deforms to generate displacement, and the deformation amount of the cantilever is obtained according to the micro displacement sensor, thereby calculating the molecular mass. However, the processing of the DNA molecule adsorption layer of this microcantilever device is complex, and there are easily errors in the adsorption of DNA molecules by the DNA molecule adsorption layer. The detection accuracy of the micro displacement sensor is not high enough, and large errors are easily generated.

[0004] A document with the patent number 201610408614 discloses a method for measuring the mass of DNA molecules using the resonance principle. It includes an exciter, a hinge support, a micro simply supported beam, a DNA molecule adsorption layer on the micro simply supported beam, the DNA molecule to be measured, and an amplitude receiver; the micro simply supported beam is excited to vibrate freely by the exciter, and the amplitude receiver detects the corresponding amplitude and frequency, and then calculates the mass of the DNA molecule. The production of the DNA adsorption layer on the micro simply supported beam is complex, and the adsorption effect is difficult to control. In addition, the large-area adsorption layer will cause changes in the elastic coefficient of the cantilever, resulting in frequency deviation during frequency measurement and generating measurement errors.

[0005] The existing technology test devices are complex, the manufacturing process of the cantilever is complex, and the degree of portability is low at the same time. Therefore, it is of great significance to design a new type of microcantilever device for detecting tiny mass. Summary of the Invention

[0006] The problem to be solved by the present invention is: when determining the mass of a tiny object by the existing method, the object to be detected is adsorbed by an adsorption method, and the mass of the tiny object is determined by detecting the change in frequency or displacement. The detection device is complex and the manufacturing process is complex. In view of the existing problems, it is possible to consider simplifying the manufacturing process of the detection device and adopting a simpler detection principle.

[0007] In order to solve the above problems, the technical solution of the present invention is as follows:

[0008] A microcantilever device for detecting tiny mass, comprising a cantilever device, a cantilever fixed substrate, an electrode plate fixed substrate, a gasket, a gasket for adjusting electrode distance, and an electrode plate. The fixed end of the cantilever device is fixed on the cantilever fixed substrate by a spring clip; a gasket is provided on the electrode plate fixed substrate, a gasket for adjusting electrode distance is provided on the gasket, the electrode plate is placed on the gasket for adjusting electrode distance and fixed on the electrode plate fixed substrate by a spring clip; a metal electrode is sputtered on the electrode plate, and a TSV through-hole is made to lead the metal electrode to the lower surface of the electrode plate. The gasket for adjusting electrode distance is U-shaped and does not contact the metal electrode on the electrode plate; the electrode plate extends a free end outward relative to the electrode plate fixed substrate, the gasket, and the gasket for adjusting electrode distance. The free end is arranged in cooperation with the microcantilever of the cantilever device and is placed above the microcantilever. One electrode is led out from the metal electrode, and the other is processed and led out on the cantilever device. An impedance analyzer or a micro-capacitance test circuit is used for capacitance measurement.

[0009] Further, the electrode plate fixed substrate has the same thickness as the cantilever fixed substrate.

[0010] Further, the gasket for adjusting electrode distance adopts a silicon steel precision gap gasket with adjustable thickness, and the thickness is greater than or equal to 5 μm.

[0011] Further, the material of the electrode plate is glass or single crystal silicon.

[0012] Further, the cantilever device contains a microchannel inside. The microcantilever on the cantilever device is formed by processing single crystal silicon material. The microchannel inside the cantilever is used to place tiny mass objects to be detected and is fabricated by SON process; at the same time, the shape of the microchannel can be changed according to actual needs.

[0013] Further, when the end of the microcantilever is placed into the object to be detected, it deforms under force, the distance between the metal electrode and the electrode processed on the cantilever device changes, and the leads of the metal electrode and the electrode processed on the cantilever device are connected to a tiny capacitance detection circuit. The tiny capacitance detection circuit detects the capacitance change; the computer system processes the capacitance data collected by the tiny capacitance detection circuit, correlates the change in capacitance with the mass of the object to be detected, and finally obtains and displays the mass of the object to be detected.

[0014] Compared with the prior art, the present invention has the following advantages;

[0015] 1. A microcantilever device for detecting tiny mass in the present invention includes a microcantilever composed of single-crystalline silicon, an electrode plate device, and a tiny capacitance detection circuit. A tiny mass object acts on the microchannel inside the cantilever, causing the cantilever to deform. By detecting the capacitance change between the cantilever and the electrode plate, the mass of the tiny mass object can be calculated.

[0016] 2. Compared with the mass detection method by adsorption in the present invention, the manufacturing process and cost of the cantilever are reduced, which can improve production efficiency. At the same time, the manufacturing of the microcantilever is simpler than that of the cantilever with an adsorption layer and has high reliability.

[0017] 3. The detection device provided by the present invention is convenient to use. When detecting the cantilever, it reduces the dependence on external optical equipment, can be carried out, realizes mobile detection, and has high application prospects.

[0018] 4. The present invention adopts a measurement principle different from that of existing measurement devices. By calculating the capacitance, it detects the mass of tiny objects. The detection device has high sensitivity, can quantitatively reflect the deformation size of the cantilever, and provides an absolute offset.

[0019] 5. The present invention solves the problem that the traditional microcantilever causes a change in the elastic constant of the cantilever due to adsorbing the detected object, resulting in a frequency shift and measurement error during measurement. At the same time, the detection device has high integratability and can effectively reduce measurement errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram after a microcantilever for detecting tiny mass in the present invention is inserted into the electrode plate; (a) is the cantilever device to be measured; (b) is the detection electrode plate device; (c) is the top view of (a); (d) is the top view of (b).

[0021] Figure 2 It is a schematic structural diagram of a microcantilever device system for detecting tiny mass in the present invention.

[0022] In the figure, 201 - cantilever fixed substrate; 202 - cantilever; 203 - spring clip for fixing the cantilever; 301 - electrode plate fixed substrate; 302 - gasket; 303 - gasket for adjusting electrode distance; 304 - spring clip for fixing the electrode plate; 305 - metal electrode on the electrode plate; 306 - electrode plate; 3 - tiny capacitance detection circuit.

[0023] Figure 3 It is a test flow block diagram. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following will further describe the present invention in conjunction with the drawings and specific embodiments.

[0025] See Figure 1As shown in the figure, it is a schematic diagram of the combination of a microcantilever device for detecting tiny mass and an electrode plate according to the present invention. Figure (c) is the top view of Figure (a), Figure (d) is the top view of Figure (b). In Figure (a), the cantilever device is fixed on the cantilever fixing substrate (201) through a spring clip (203); the electrode plate fixing substrate (301) in Figure (b) has the same thickness as the cantilever fixing substrate (201). The electrode distance adjusting gasket (303) is placed on the gasket (302), and a precision silicon steel clearance gasket is used, and the thickness can be adjusted from 5μm. The electrode plate (306) is placed on the electrode distance adjusting gasket (303) and fixed on the electrode plate fixing substrate (301) with a spring clip (304). A metal electrode (305) is sputtered on the electrode plate (306), and a TSV through-hole is made to lead the metal electrode to the surface of the electrode plate. The electrode distance adjusting gasket (303) is U-shaped and does not contact the metal electrode on the electrode plate. The material of the electrode plate can be glass or single crystal silicon, Figure 1 Figure (d) is the top view when the electrode plate is a transparent glass.

[0026] As a specific embodiment of the present invention, a microcantilever for detecting tiny mass according to the present invention may have a microchannel inside, and the shape of the microchannel can be processed according to actual needs. The microchannel is fabricated by the SON process. The microcantilever is fabricated from single crystal silicon.

[0027] A microcantilever for detecting tiny mass according to the present invention is placed with a tiny mass object to be detected, and deforms under force. The object to be detected is placed in the microchannel inside the microcantilever. After the object to be detected is placed, the microcantilever will deform under force.

[0028] See Figure 2 As shown in the figure, a microcantilever device system for detecting tiny mass proposed by the present invention, when testing, Figure 1 Figure (b) and Figure 1 the device shown in Figure (a) are placed on the same platform. The electrode plate is placed on the cantilever. One electrode is led out from the metal electrode (305), and the other electrode is processed and led out on the cantilever. Capacitance measurement can be performed using an impedance analyzer or a micro-capacitance test circuit.

[0029] When the microcantilever is not placed with the object to be detected, the microcantilever has not deformed yet, and the distance from the metal electrode (305) of the electrode plate is d. The distance between the electrode and the surface of the cantilever can be adjusted by the spacer (303) for electrode distance adjustment. By replacing spacers with different thicknesses, the spacing d can be precisely adjusted. The cantilever is made of single-crystalline silicon with low resistivity and can be led out by a probe. The leads are taken from the metal electrode (305) on the surface of the electrode plate on the electrode plate, and the two leads are connected to the micro-capacitance detection circuit (3) through a wire. Connected to the computer processing system through the micro-capacitance detection circuit (3), the capacitance value of the parallel-plate capacitor formed by the electrode plate and the microcantilever can be obtained, denoted as C0. After the microcantilever is placed with the object to be detected, it will produce a small bending and deformation, denoted as Δd. The capacitance value between the deformed microcantilever and the metal electrode of the electrode plate By detecting the capacitance value of the microcantilever after the object to be detected is placed, and then through the data processing of the computer system, the mass of the object on the microcantilever can be obtained. The specific computer processing process includes a calibration process and a measurement process. The flow chart of the processing is as Figure 3 shown. Particles of standard mass are applied to several fixed positions of the known cantilever. According to the measured capacitance, curves of capacitance and mass, and the relationship curve between capacitance and the position of the cantilever are plotted. Then, the fitting relationship between capacitance and mass and the acting position on the beam is obtained from the curves; during measurement, according to the measured capacitance and the acting position of the mass on the cantilever, the mass to be measured is obtained by substituting into the fitting relationship.

Claims

1. A microcantilever device for detecting tiny mass, characterized in that, It includes a cantilever beam device (202), a cantilever beam fixing substrate (201), an electrode plate fixing substrate (301), a gasket (302), a gasket for electrode distance adjustment (303), and an electrode plate (306). The fixed end of the cantilever beam device (202) is fixed on the cantilever beam fixing substrate (201) through a spring clip (203); the electrode plate fixing substrate (301) is provided with a gasket (302), the gasket for electrode distance adjustment (303) is provided on the gasket (302), the electrode plate (306) is placed on the gasket for electrode distance adjustment (303) and fixed on the electrode plate fixing substrate (301) with a spring clip (304); a metal electrode (305) is sputtered on the electrode plate (306), and a TSV through-hole is used to lead the metal electrode to the lower surface of the electrode plate (306). The gasket for electrode distance adjustment (303) is U-shaped and does not contact the metal electrode on the electrode plate (306); a free end of the electrode plate (306) extends outward relative to the electrode plate fixing substrate (301), the gasket (302), and the gasket for electrode distance adjustment (303). This free end is arranged in cooperation with the micro-cantilever beam of the cantilever beam device (202) and is placed above the micro-cantilever beam. One electrode is led out from the metal electrode (305), and the other electrode is processed and led out on the cantilever beam device. A capacitance measurement is carried out using an impedance analyzer or a micro-capacitance test circuit.

2. The microcantilever device for detecting minute mass according to claim 1, characterized in that, The electrode plate fixing substrate (301) has the same thickness as the cantilever beam fixing substrate (201).

3. A microcantilever device for detecting tiny mass according to claim 1, characterized in that, The gasket for electrode distance adjustment (303) uses a silicon steel precision gap gasket with a thickness greater than or equal to 5 μm.

4. A microcantilever device for micro mass detection according to claim 1, characterized in that, The material of the electrode plate (306) is glass or single crystal silicon.

5. A microcantilever device for micro mass detection according to claim 1, characterized in that, The cantilever beam device contains a microchannel inside. The micro-cantilever beam on the cantilever beam device is formed by processing single crystal silicon material. The microchannel inside the cantilever beam is used to place the tiny mass object to be detected and is fabricated using the SON process; at the same time, the shape of the microchannel can be changed according to actual requirements.

6. The microcantilever device for detecting tiny mass according to claim 1, characterized in that When the end of the micro-cantilever beam is placed into the object to be detected, it deforms under force, and the distance between the metal electrode (305) and the electrode processed on the cantilever beam device changes. The leads of the metal electrode (305) and the electrode processed on the cantilever beam device are connected to the micro-capacitance detection circuit (3), and the micro-capacitance detection circuit (3) detects the capacitance change; the computer system processes the capacitance data collected by the micro-capacitance detection circuit, correlates the change in capacitance with the mass of the object to be detected, and finally obtains and displays the mass of the object to be detected.

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