A nanonewton-level force detection device and its application

Abstract

The present invention discloses a device for detecting nanonewton-level forces, comprising: one or more micro-nano elastic members; a force-bearing platform arranged on the top of the micro-nano elastic member; and a displacement detection unit for detecting displacement change information of the force-bearing platform. The present invention also discloses an application of the above-mentioned device in detecting the mass or force of tiny particles. The advantages of the method of the present invention are: based on the spiral micro-nano spring, the test accuracy can reach the nanogram or even picogram level, and the force analysis can reach the nanonewton or even piconeum level to realize single-cell detection; the static in-situ optical measurement method can use low-intensity laser for contactless detection, eliminating the damage to cells caused by external vibration signals; the constituent materials, structural parameters, spatial distribution and sensitivity of the spiral spring and the force-bearing platform can be adjusted according to the object shape and estimated weight, and the scalability is strong.

Description

Technical Field

[0001] The present invention belongs to the field of force sensing technology, and in particular relates to a nanonewton-level force detection device and its application. Background Art

[0002] Measuring nanonewton-level forces is a hot topic and a challenge in current nanoscience research. For example, measuring the mass or weight of tiny particles, or analyzing the forces acting on them during motion, are key areas of research. Tiny particles are organic, inorganic, or clustered objects with characteristic dimensions ranging from hundreds of micrometers (μm) to nanometers (nm) and masses ranging from hundreds of nanograms (ng) to picograms (pg). In particular, tiny objects such as cells are the fundamental building blocks of life and represent a major potential target for biological science applications. In-depth analysis of fundamental processes such as the generation, growth, division, and aging of living cells will deepen our understanding of life and promote the advancement of human biology. During interactions with viruses and drugs, changes in cell mass and weight, as well as dynamic changes in cell adhesion (at the nanonewton level), are crucial parameters for assessing cell health. Effectively measuring physical parameters such as changes in cell mass and real-time monitoring of force changes during single-cell manipulations (such as cell membrane puncture) can greatly accelerate the development of effective drugs and advance human health.

[0003] The flow cytometer, which was introduced in the 1950s, dynamically measures the volume and weight of cells by detecting changes in light intensity caused by scattering from cells suspended in a fluid. However, the flow cytometer cannot provide high-precision single-cell mass data, nor is it suitable for tracking changes in the mass and weight of single cells over long periods of time. At the same time, the Coulter cell counter, which was developed based on the resistance method, electric pulse method, and induction principles, detects the fluid conductivity of cells as they pass through specific small-pore tubes, achieving simultaneous measurement of cell number and volume data. However, the Coulter cell counter cannot accurately identify and locate cells with abnormal morphology, and its weighing accuracy cannot reach the nanogram level of a single cell.

[0004] In recent years, a single-cell weighing scheme based on a micro-nano silicon-based cantilever structure (Inertial picobalance reveals fast mass fluctuations in mammalian cells, Newton, Corina Beerli, Jason Mercer, Christoph Gerber & Daniel J. Müller, Nature, 2017, 550, 500-505) has been proposed and applied to long-term cell weight monitoring. This is a measurement method using laser interferometry. The cells attached to the cantilever produce a frequency domain characteristic peak offset due to external mechanical vibration. By detecting this frequency domain characteristic peak drift, single-cell dynamic weighing is achieved. Although the measurement accuracy reaches the single-cell level, high-frequency mechanical vibrations can easily cause damage to the measured cells and many other problems.

[0005] Generally speaking, current commercial devices such as flow cytometers and Coulter cell counters cannot achieve single-cell weighing accuracy, record mass data over long periods of time, or be integrated with fluorescence signal acquisition instruments. Recently reported micro-nano silicon cantilever cell balances use dynamic measurement schemes that can generate external stimuli during cell development and cannot detect in situ signal data. Summary of the Invention

[0006] The present invention provides a nanonewton-level force detection device, which can quickly realize the detection of nanonewton-level forces, etc.

[0007] The present invention also provides a method for detecting the mass, weight or force of tiny particles using the above detection device.

[0008] The present invention provides a static weighing method for tiny particles such as cells, overcoming the shortcomings of traditional flow cytometers, Coulter cell counters, etc., such as the inability to monitor cell mass data over a long period of time. It also eliminates the potential irreversible damage to cells caused by mechanical high-frequency vibrations of dynamic cantilever cell balances. It has a sensitivity of up to nanograms (ng) or even picograms (pg), and can be used for long-term monitoring of mass / weight information during the dynamic development of cells, as well as data such as adhesion.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A nanonewton-level force detection device, comprising:

[0011] One or more micro-nano elastic members;

[0012] A force-bearing platform arranged on top of the micro-nano elastic member;

[0013] A displacement detection unit for detecting displacement change information of a force-bearing platform.

[0014] In the present invention, the microparticles include organic, inorganic or clustered micro-objects with sizes ranging from hundreds of micrometers (μm) to nanometers (nm) and masses ranging from hundreds of nanograms (ng) to picograms (pg).

[0015] In the present invention, the force-bearing platform bears the force required for detection. When used for mass or weight detection of microparticles, the force-bearing platform acts as a weighing platform to contact and carry microparticles (groups) such as single cells or cell clusters, metal / non-metallic nanoparticles, or adhere to or connect microobjects, thereby achieving detection (or monitoring) of the weight or mass of microparticles or force analysis. The force-bearing platform can be a flat or plate-like structure or a composite structure with hook-like protrusions. The force-bearing platform can be a solid or hollow structure.

[0016] In the present invention, the basic shape of the force-bearing platform can be customized according to the characteristics of the force to be detected or the morphology of the microparticles, and can be a flat cylinder, a cube, or a cuboid. The weighing platform in the present invention is preferably in the shape of a disk, with a flat upper surface and a lower surface supported by a micro-nano elastic member (nano-helix).

[0017] Preferably, the bottom end of the micro-nano elastic member is fixed to a substrate, and the top end of the micro-nano elastic member is fixed to the bottom end of the force-bearing platform.

[0018] Preferably, the displacement detection unit detects the displacement change of the force-bearing platform based on a combination of one or more of laser interferometry, spectral information, and microscopy. That is, the displacement detection unit is a device or apparatus that detects the displacement change of the force-bearing platform based on a combination of one or more of an optical signal measurement method (laser interferometry, spectral information) and a microscope. In the technical solution of the present invention, based on laser interferometry, spectral information, or microscopic detection, the microscopic force exerted on the force-bearing platform is obtained by compressing and stretching the micro-nano elastic member (helical micro-nano spring), or directly obtaining the mass / weight information of the microparticles.

[0019] Preferably, the optical signal measurement method measures the intensity of transmitted light or reflected light, and spectral change information. During actual detection, a low-intensity laser is used to irradiate the force platform and / or micro-nano spring, or a microscope is used to measure the displacement of the weighing platform and determine the tiny force information borne by the force platform, so as to achieve non-contact in-situ measurement.

[0020] In the present invention, the signal measurement method adopts low-intensity laser.

[0021] In the present invention, the displacement detection unit includes but is not limited to a laser displacement sensor, an ultrasonic displacement sensor, etc. A device that directly captures images, such as a microscope, may also be used to detect displacement.

[0022] Preferably, the micro-nano elastic member is a micro-nano spring composed of spiral nanowires (or nano-helices). The material of the spiral micro-nano spring is not limited to polymers, but can be metals such as gold and silver, semiconductors such as silicon, or other composite materials.

[0023] In the present invention, the helical micro-nano spring is based on nanoelastic parts such as coil springs, and is composed of a single group of single or multiple coil springs, or multiple groups of single or multiple groups of multiple coil springs, or multiple groups of coil spring arrays, or a combination of any one or two or more helical micro-nano springs. Its elastic coefficient is in line with the nanonewton level force measurement range (weighing of tiny objects such as cells, adhesion force, etc.), which is on the order of pg / nm or pN / nm.

[0024] In the present invention, the elastic coefficient of the micro-nano spring is 0.1 to 1000 nN / μm. Preferably, the elastic coefficient of the micro-nano spring is 0.1 to 50 nN / μm. Preferably, the cross-sectional area of ​​the spring wire of the micro-nano spring is 1 to 10 μm. 2 ; The average diameter of the micro-nano spring is 0.1 to 50 μm; the number of turns of the micro-nano spring is 1 to 5 turns.

[0025] In the present invention, the helical micro-nano spring is composed of a left-handed, right-handed, or a combination of left and right-handed nanohelical wire. The lower end of the helical wire is fixed to the substrate base, and the upper end is connected to the force-bearing platform. The helical wire undergoes corresponding displacement changes depending on the force (weight) borne on the substrate.

[0026] In the present invention, the force-bearing platform is supported by a single micro-nanospring or multiple coaxially arranged micro-nanosprings; alternatively, the force-bearing platform is supported by one or more mutually non-interfering micro-nanospring groups, wherein each micro-nanospring group is composed of two or more micro-nanosprings. Preferably, the force-bearing platform is supported by multiple coaxially arranged micro-nanosprings with consistent helical directions; alternatively, the force-bearing platform is supported by one or more mutually non-interfering micro-nanospring groups, wherein each micro-nanospring group is composed of two micro-nanosprings with symmetrical helical directions and no interference.

[0027] The spiral lines in the present invention are preferably combined into a single group of three to five spirals, that is, preferably, the force-bearing platform is supported by three to five coaxially arranged micro-nano springs with consistent spiral directions; due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific combinations included in the scope.

[0028] In the present invention, the height, number of turns, spiral diameter, nanowire diameter, wire spacing, and wire uniformity of the nanohelix can be adjusted according to the preparation method and target mass sensitivity. The spiral wires in the present invention are preferably combined into one turn with a diameter of about 20 μm. The cross section of the spiral wire can be square, circular, elliptical, rectangular, trapezoidal or any other shape, or any one or a combination of two or more of the above. The cross section of the spiral wire in the present invention is preferably rectangular, and its cross section is rectangular (approximately 1 μm × 2 μm in size).

[0029] In the present invention, the constituent materials, combined number, rotation direction, and spatial distribution of the nanohelix can be flexibly adjusted according to the properties of the incident light, the preparation method, the target sensitivity, and the cell morphology.

[0030] In the present invention, the nanohelix can be prepared using two-photon laser direct writing technology, or other nano-fabrication technologies, such as photolithography, electron beam etching and other processes, to achieve overall micro-nano fabrication and molding, and has good application scenarios.

[0031] As an advantage, it also includes:

[0032] A storage module, pre-storing relationship data between displacement change information of the force-bearing platform and force information of the force-bearing platform;

[0033] The comparison module receives the displacement change information of the force-bearing platform output by the displacement detection unit, and compares the information with the relationship data in the storage unit to obtain the corresponding force information of the force-bearing platform;

[0034] The above-mentioned storage module, comparison module, etc. can be an integrated control chip structure, or a computer or integrated circuit with the same function.

[0035] Optional, also includes:

[0036] A display screen for displaying mass / weight data and force analysis of the tiny particles.

[0037] The present invention further provides a method for detecting the mass / weight or force of tiny particles using any of the above detection devices, comprising:

[0038] Place the tiny particles to be tested on the force-bearing platform, or adhere or connect the tiny particles to the force-bearing platform;

[0039] Utilizing the displacement detection unit to detect displacement change information of the force-bearing platform;

[0040] According to the relationship between the displacement change information of the force-bearing platform and the force information of the force-bearing platform, the mass / weight of the tiny particles to be measured is output, or the force information of the tiny particles is output, recorded and analyzed.

[0041] Preferably, the detection device is calibrated using an atomic force microscope to obtain the relationship between the displacement change information of the force-bearing platform and the force information of the force-bearing platform. Using the method of the present invention, an atomic force microscope can be used for pre-calibration to obtain the relationship between the atomic force cantilever force and the displacement change of the force-bearing platform. A curve function of the relationship between the atomic force cantilever force and the displacement change of the force-bearing platform can be obtained by methods such as curve fitting. This function can be stored in a storage module or a computer for easy reference during detection.

[0042] The present invention also provides a method for monitoring mass / weight changes, cell adhesion changes, and force changes during cell injection, puncture, extraction, and other operations using the detection device described in any of the above technical solutions.

[0043] The outstanding advantages of the present invention are: based on the spiral micro-nano spring, single-cell level mass or weight detection can be achieved, the test accuracy can reach nanograms or even picograms, and the force analysis can reach nanonewtons or even piconewtons, which can realize single-cell detection; the static in-situ measurement method uses low-intensity laser or microscope technology for contactless monitoring, eliminating the damage to cells caused by external vibration signals; the constituent materials, structural parameters, and spatial distribution of the spiral spring and the force platform can be adjusted according to the morphology of the micro-nano object, and the scalability is strong.

[0044] The present invention provides a method suitable for measuring important physical parameters of tiny objects, which can be used to monitor information such as changes in weight, mass, and cell adhesion during cell growth, development, and death. It can be expanded to applications such as monitoring tiny pressures in microfluidic systems. It has the advantages of high precision, stable and reliable system, strong scalability, and a wide range of application scenarios, and has good development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a working principle diagram of a nanonewton-level force detection device.

[0046] Figure 2 This is a scanning electron microscope photo of the helical micro-nano weighing spring.

[0047] Figure 3 Sensitivity calibration data for spiral micro-nano weighing springs. DETAILED DESCRIPTION

[0048] For ease of understanding, the present invention will be further described below with reference to the accompanying drawings. Note that the following embodiments are only preferred embodiments of the present invention and are only used to help understand the present invention, and therefore should not be considered to limit the scope of the present invention.

[0049] like Figure 1As shown, a nanonewton-level force detection device includes a spiral micro-nano spring 101a and a micro-nano spring 101b, a force-bearing platform 102 and a displacement detection unit.

[0050] Taking the mass detection of tiny particles as an example, the force-bearing platform 102 is a horizontal plate-like structure used to support a tiny object 103 (a tiny particle) of mass (or weight) to be detected. The helical micro-nanospring 101a and micro-nanospring 101b are made of helical nanowires (or nanohelices), with their top ends fixed to the force-bearing platform 102 and their bottom ends fixed to the top surface of the substrate 100.

[0051] The working principle of this quality detection method is as follows: a tiny object 103 such as a cell is placed on a force-bearing platform 102, and the micro-nano springs 101a and 101b are deformed due to compression. The displacement caused by the compression deformation of the micro-nano springs 101a and 101b is measured by incident light 104 and reflected light 105 (which can be the incident light and reflected light in a laser displacement sensor), or by using an atomic force microscope 106 (which can also be an ordinary microscope). The relationship between the displacement and the force on the force-bearing platform is used to obtain the weight and mass information of the tiny object such as the cell.

[0052] Figure 2 (a) shows a set of helical micro-nanospring structures and platforms fabricated using micro-nanotechnology. (b) shows a magnified view of one of these structures and platforms, along with the corresponding dimensions. The space enclosed by the micro-nanospring structures is hollow cylindrical, with optimal parameters: an overall helical height of approximately 60 μm and a helical diameter of approximately 20 μm. The lower end of the micro-nanospring serves as a substrate, while the upper end serves as a force-bearing platform. Figure 2 The exhibited micro-nanostructure was produced using two-photon laser direct writing technology (specifically, a two-photon micro-nano 3D printer from Nanoscribe, Germany). The structure is integrally formed from a polymer (IP-DIP, Nanoscribe, Germany), boasting high Young's modulus, high sensor sensitivity, and high integration. Other nanofabrication techniques, such as photolithography and electron beam etching, can also be used. The helical micro-nanospring is not limited to polymers; it can also be made from metals such as gold and silver, semiconductors such as silicon, or other composite materials.

[0053] Figure 1 In the schematic diagram, the micro-nano spring is composed of a group of two parallel helices, that is, 101a is a right-handed nanohelix and 101b is a left-handed nanohelix. Figure 2A set of three left-handed helices is used. Depending on the requirements, the micro-nano spring can be composed of left-handed, right-handed, or a combination of left-handed and right-handed nanohelices. The number of coil springs can be a single set, a single set of multiple coils, multiple sets of single coils, multiple sets of multiple coils, or an array of coil springs, or a combination of any one, two, or more coil micro-nano springs. Due to space limitations and for the sake of brevity, this invention does not exhaustively list the specific combinations included in the scope.

[0054] Figure 1 In the figure, the nanohelix is ​​a three-turn uniform nanowire with a circular cross section. Figure 2 The medium nanohelix is ​​a single, uniform nanowire with a rectangular cross-section measuring approximately 1μm x 2μm. Based on actual needs, the overall height, number of turns, helix diameter, nanowire diameter, wire spacing, and wire uniformity of the nanohelix can be adjusted based on the preparation method and target mass sensitivity. The helix cross-section can be square, circular, elliptical, rectangular, trapezoidal, or other optimized structures. Furthermore, the nanohelix's constituent materials, number of combinations, rotation direction, and spatial distribution can be flexibly adjusted based on the properties of the incident light, preparation method, target sensitivity, and cell morphology.

[0055] exist Figure 1 In the figure, the lower ends of the helical micro-nano springs 101a and 101b are fixed to the substrate 100, and the upper ends are connected to the cell force-bearing platform 102, presenting a rectangular flat plate structure. Figure 2 In the experiment, the force-bearing platform is disc-shaped with a diameter of about 20 μm and a thickness of about 2 μm. The basic shape of the force-bearing platform can be customized according to the cell morphology and can be a flat cylinder, cube, cuboid, or other optimized shapes.

[0056] Figure 1 The schematic diagram shows a method of measuring weight using optical means or a microscope. Corresponding to the optical method, the displacement of the force-bearing platform 102 is detected by the incident light 104 and the reflected light 105, and the weight / mass information of the tiny object is measured. The working principle of the optical method is: when there is no tiny object 103, the force-bearing platform 102 receives the incident light 104, and reflects a certain light 105, and records the initial light signal; when the tiny object 103 is placed on the force-bearing platform 102, the platform produces a downward displacement, causing the incident light 104 and the reflected light 105 to undergo changes in light intensity, spectrum and other signals. By analyzing the signal changes, the weight / mass information is obtained. For the microscope detection method, the images of the force-bearing platform 102 before and after weighing the tiny object 103 can be selected, and the displacement of the force-bearing platform 102 can be compared to obtain the weight / mass information.

[0057] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above Figure 1 and Figure 2The specific details in the above description may be modified in a variety of simple ways within the technical concept of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0058] Before using the device or method of the present invention for quality detection, it can be calibrated in advance to obtain the relationship between the displacement of the force-bearing platform 102 and the force on the force-bearing platform 102, and then during the detection, the force information of the force-bearing platform 102 can be obtained from the obtained displacement of the force-bearing platform 102, and then the mass or weight of the tiny object on the force-bearing platform 102 can be obtained.

[0059] Figure 3 A spiral micro-nano weighing spring calibration method and test sensitivity verification method are demonstrated. Figure 3 Figure (a) shows a calibration experiment for a helical micro-nano weighing spring. The weighing spring uses three sets of helical wires (each with a single turn). The overall height is approximately 60 μm, the helical diameter is approximately 20 μm, and the nanowire cross-section is rectangular, approximately 1 μm x 2 μm. The force-bearing platform is disc-shaped, with a diameter of approximately 20 μm and a thickness of approximately 2 μm.

[0060] The calibration process is as follows: the atomic force microscope force probe is pressed on the force platform. The force probe can monitor the force applied by the probe and the relative displacement distance. When the nanohelix is ​​compressed downward, the corresponding force data and displacement distance are recorded, thereby calibrating the nanohelix weighing device.

[0061] Figure 3 Panel (b) shows the calibration data for the device. The horizontal axis represents the relative displacement of the cell measurement platform (unit: μm, variable: x), and the vertical axis represents the applied force (unit: nanonewtons nN, variable: y). The black circles represent the original data, and the straight line represents the fitted line. The fitting formula is: y = kx + b, where k is the spring sensitivity (unit: nN / μm), b is a constant, x is the displacement, and y is the force. Figure 3 The sensitivity of the medium-helical micro-nano weighing spring is 0.5339nN / μm, which is equivalent to about 54pg / nm. The average cell mass is about 2ng. Therefore, the experimentally calibrated sensitivity of the spring is consistent with the cell weight measurement range, proving that this method can effectively monitor cell weight.

[0062] Note that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, so the measured sensitivity values ​​may be different. In order to avoid unnecessary repetition, the present invention will not further explain various possible combinations.

Claims

1. A nanonewton force detection device, characterized in that: include: One or more micro-nano elastic members; A force-bearing platform provided on top of the micro-nano elastic member; A displacement detection unit for detecting displacement change information of the force-bearing platform; The micro-nano elastic member is a micro-nano spring composed of spiral nanowires; The elastic coefficient of the micro-nano spring is 0.1~50nN / μm; the cross-sectional area of ​​the spring wire of the micro-nano spring is 1~10μm 2 The average diameter of the micro-nano spring is 0.1~50μm; the number of turns of the micro-nano spring is 1~5 turns; The micro-nano spring is obtained by using two-photon laser direct writing technology; its composition is a high molecular polymer IP-DIP; The force-bearing platform is supported by one or more coaxially arranged micro-nano springs; or the force-bearing platform is supported by one or more groups of micro-nano springs that do not interfere with each other, wherein each group of micro-nano springs consists of two or more micro-nano springs; Also includes: A storage module, pre-storing relationship data between displacement change information of the force-bearing platform and force information of the force-bearing platform; The comparison module receives the displacement change information of the force-bearing platform output by the displacement detection unit, and compares the information with the relationship data in the storage unit to obtain the corresponding force information of the force-bearing platform.

2. The nanonewton force detection device according to claim 1, characterized in that: The bottom end of the micro-nano elastic member is fixed to a substrate.

3. The nanonewton force detection device according to claim 1, characterized in that: The displacement detection unit detects the displacement change of the force-bearing platform based on a combination of one or more optical signal measurement methods and microscope measurement.

4. Use of the detection device according to any one of claims 1 to 3 in detecting the mass or force of tiny particles, characterized in that: include: Place the tiny particles to be tested on the force-bearing platform, or adhere or connect the tiny particles to the force-bearing platform; Utilizing the displacement detection unit to detect displacement change information of the force-bearing platform; According to the relationship between the displacement change information of the force-bearing platform and the force information of the force-bearing platform, the mass of the tiny particles to be measured is output, or the force information of the tiny particles is output, recorded and analyzed.

5. The use according to claim 4, characterized in that include: The detection device is calibrated using an atomic force microscope to obtain the relationship between the displacement change information of the force-bearing platform and the force information of the force-bearing platform.

6. A method for monitoring changes in cell mass and cell adhesion during cell growth, development, and death, and changes in force during one or more operations of cell injection, puncture, and extraction using the detection device according to any one of claims 1 to 3.

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