CN106525669A - Light momentum-excited nano beam microparticle mass measuring device and method - Google Patents

Abstract

The invention provides a light momentum excitation nanobeam quality measurement device, including a sinusoidal light momentum excitation generating device and a micro-mass detection device, the monochromatic light of the upper laser and the lower laser illuminates the light holes of the upper disc and the lower disc respectively, Drive the motor to drive the shaft to rotate, which can generate light momentum excitation similar to sinusoidal distribution, and stimulate the nanobeam to vibrate. The Wheatstone bridge circuit can output the signal, and after being amplified by the signal amplifier, the spectrum analysis can be performed to obtain vibration information images in the time domain and frequency domain of vibration, and vibration parameters such as vibration amplitude and vibration frequency. Changing the rotational speed of the drive motor of the photomomentum excitation generating device, the photomomentum excitation frequency changes accordingly. When the nanobeam resonates, the output current signal value is the largest, and the resonance vibration frequency of the nanobeam can be detected by measuring the peak value of the voltage change. Through calculation, the viscosity at the end of the nanobeam is obtained. The size of the attached additional mass achieves the purpose of measuring the mass of nanoparticles.

Description

Apparatus and method for mass measurement of nanobeams and microparticles excited by light momentum

technical field

The patent of the present invention relates to a nano-micro mass detection device, in particular to a nano-micro mass measurement device, which belongs to the field of nano-micro mass detection.

Background technique

For mechanical resonators, nanomicrocantilevers are important devices for detecting weak force signals. In order to achieve higher mechanical sensitivity, it is necessary to use smaller micro-oscillators. However, how to drive and detect the vibration of the micro-resonator has become one of the problems that restricts the improvement of the accuracy of measuring the mass of nano-particles. Based on the basic principles of quantum mechanics, in the process of driving and measuring, the driving and measuring equipment will cause disturbance and damage to the measured object, introduce unnecessary noise, and reduce the accuracy of measurement. In terms of vibration signal extraction of nano-micro resonators, the method of detecting displacement signals is usually used to convert displacement signals into optical, electrical, magnetic and other signals. By measuring these signals, high-sensitivity displacement measurement can be realized. The size and geometry of mechanical vibrators have strict requirements, and it is difficult to apply to the measurement of nanometer and sub-nanometer scale mechanical vibrators, which potentially restricts the measurement of high-precision quality. Optical momentum drive is a non-contact driving method. As the driving excitation source of the nano-micro resonator, it reduces the influence of the drive on the measured object, can stimulate the micro-oscillator with a smaller size, and improves the accuracy and accuracy of the nano-micro mass measurement. resolution.

The invention can be widely used in the detection of nano-particles in the fields of bacteria, virus detection, air pollutant detection and the like, and can even be used for single molecule or atomic mass detection.

Contents of the invention

Aiming at the current situation that it is difficult to measure the quality of nano and micro particles, the invention proposes a device and method for measuring the quality of nano and micro particles.

The solution adopted by the present invention to solve the technical problem is: the optical momentum excitation nano-beam mass measurement device includes a sinusoidal optical momentum excitation generating device and a micro-mass detection device, which is characterized in that:

The photomomentum excitation generating device consists of two upper disks, lower disks, upper lasers, lower lasers, shafts, upper bearings, lower bearings, drive motors and fixed ends fixed on the same shaft. The upper end of the shaft and A bearing is respectively installed at the lower end of the shaft, and a driving motor is hinged at the lower end of the shaft, and the driving motor drives the shaft to rotate; the radius of the upper disc and the lower disc are both 12mm, and the upper disc and the lower disc are equal-area squares along the distance from the axis. The square light hole has a side length of 5 μm, and the side length is much longer than the wavelength of light. It is arranged with a circle line with a radius of 10mm as the center line. The distance between the holes is four times the width of the light hole, and the distance between the two adjacent light holes of the upper disk and the lower disk is twice the width of the light hole. The upper laser and the lower laser are fixed on the base. When the monochromatic light of the upper laser and the lower laser irradiates the light hole respectively, the drive motor drives the shaft to rotate, which can generate light momentum excitation similar to a sinusoidal distribution, and excite the nanobeam to vibrate.

The micro-mass detection device is composed of nano-beams, resistance layer resistance, Wheatstone bridge and nano-particles to be measured, and is characterized in that:

One end of the nano-beam is fixed and the other end is free. The nano-beam is made of silicon single crystal material. The length, width and height are 40 μm, 5 μm and 0.8 μm respectively. The width of the nano-beam is smaller than the side length of the square light hole. The particles are placed at the end of the nano-beam, and the sinusoidal light excitation acts on the nano-beam near a quarter of the end.

The upper layer of the nanobeam near the fixed end is sputtered by argon ions to form a thin layer of resistance layer resistance, the depth of argon ion sputtering is 10-50nm, the resistance value of the resistance layer changes with the deformation of the nanobeam, and the length of the resistance layer When it becomes longer, the resistance becomes larger, and vice versa, it becomes smaller. The initial resistance of the resistance layer resistance is 15kΩ, and the other resistances of the Wheatstone bridge are all 15kΩ.

The Wheatstone bridge is connected to both ends of the resistance layer resistance, the other two terminals of the Wheatstone bridge are connected to a constant external voltage, and the voltage source voltage is 5 volts; the sinusoidal light momentum excitation acts on the upper and lower surfaces of the nanobeam, and the photon moves Momentum drives the vibration of the nanobeam. When the nanobeam vibrates, the resistance value of the resistive layer of the nanobeam changes. The resistance change causes the current signal in the Wheatstone bridge circuit to change. By detecting the change of the current signal, the vibration frequency of the nanobeam can be detected.

The nanobeams are forced to vibrate under the excitation of alternating light momentum, and the resistance value of the resistance layer pasted on the root of the nanobeams changes. The Wheatstone bridge circuit can be used to output the signal, and after being amplified by the signal amplifier, the frequency spectrum can be obtained. Through the analysis, the vibration time domain and frequency domain vibration information images are obtained, and vibration parameters such as vibration amplitude and vibration frequency are obtained. Changing the rotational speed of the drive motor of the photomomentum excitation generating device, the photomomentum excitation frequency changes accordingly. When the nanobeam resonates, the output current signal value is the largest, and the resonance vibration frequency of the nanobeam can be detected by measuring the peak value of the voltage change. Through calculation, the viscosity at the end of the nanobeam is obtained. The size of the attached additional mass achieves the purpose of measuring the mass of nanoparticles.

Monochromatic light is irradiated vertically on the upper surface of the nanobeam, and the light momentum excitation force generated by the light radiation passing through the aperture is In the formula, P is the power of the incident light passing through the light hole, α is the force efficiency of the incident light, n is the refractive index of the surrounding medium, c is the speed of light, k is the number of light holes on the disk, and ω is Disc speed.

When the nano-beam resonates, the value of the disk speed ω at the time of resonance is measured, and the mass of the nano-particles is in, ρ is the linear density of the nanobeam, E is the modulus of elasticity of the nanobeam, l is the length of the nanobeam, b is the width of the nanobeam, and h is the height of the nanobeam.

Compared with the prior art, the present invention has the following advantages:

1. Light momentum driving is a non-contact driving method, which does not generate mechanical noise, has fewer measurement interference factors, and has high measurement sensitivity.

2. The double-disk light-transmitting device can generate light momentum excitation similar to a sinusoidal distribution, excite the vibration of the nano-beam, and perform frequency-sweeping measurement.

Description of drawings

Figure 1 Nano-beam nano-particle detection device;

Fig. 2 optical momentum excitation switch diagram through the optical disk;

Fig. 3 Schematic diagram of photomomentum excitation demonstration.

In the figure, 1, fixed end 2, upper bearing 3, upper disk 4, lower disk 5, nanoparticle 6, lower laser 7, shaft 8, drive motor 9, lower bearing 10, monochromatic light 11, base 12 , nanobeam 13, resistive layer resistance 14, Wheatstone bridge 15, voltage source 16, signal amplifier 17, upper laser 18, optical hole 19, light momentum excitation

detailed description

Below in conjunction with accompanying drawing, make further detailed description:

The main structure of this embodiment includes a sinusoidal light momentum excitation 19 generating device and a micro-mass detection device. The photomomentum excitation 19 generating device consists of two upper discs 3, lower discs 4, upper laser 17, lower laser 6, shaft 7, upper bearing 2, lower bearing 9, and drive motor fixed on the same shaft 7. 8 and the fixed end 1, the upper end and the lower end of the shaft 7 are respectively equipped with a bearing, the lower end of the shaft 7 is hinged with a drive motor 8, and the drive motor 8 drives the shaft 7 to rotate; the radius of the upper disc 3 and the lower disc 4 are both 12mm, and the upper Disc 3 and lower disc 4 have square light holes 18 of equal area along the same distance from the axis. The side length of square light hole 18 is 5 μm, and the side length is much longer than the wavelength of light. A circle with a radius of 10 mm The line is the center line, the distance between two adjacent light holes 18 is equal, the distance between two adjacent light holes 18 is four times the width of the light hole 18, and the upper disc and the lower disc are adjacent to each other. The distance between them is twice the width of the clear aperture. The upper laser 17 and the lower laser 6 are fixed on the base 11. When the monochromatic light 10 of the upper laser 17 and the lower laser 6 illuminates the light hole 18 respectively, the drive motor 8 drives the shaft 7 to rotate, which can generate light momentum excitation 19 similar to a sinusoidal distribution. , to excite the nanobeams to vibrate.

The micro-mass detection device is composed of a nano-beam 12, a resistance layer resistance 13, a Wheatstone bridge 14 and nano-micro particles 5 to be measured. One end of the nanobeam 12 is fixed and the other end is free. The nanobeam 12 is made of silicon single crystal material, and its length, width and height are 40 μm, 5 μm and 0.8 μm respectively. The width of the nanobeam 12 is smaller than the side length of the square light hole 18, The nanoparticle 5 to be measured is placed at the end of the nanobeam 12, and the sinusoidal light excitation acts on the quarter of the nanobeam 12 from the end.

The upper layer of the nano-beam 12 near the fixed end is sputtered by argon ions to form a thin-layer resistance layer resistance 13, the depth of argon ion sputtering is 10-50nm, and the resistance value of the resistance layer changes with the deformation of the nano-beam 12, When the length of the resistance layer becomes longer, the resistance becomes larger, and on the contrary, it becomes smaller. The initial resistance of the resistance layer resistance 13 is 15kΩ, and the other resistances of the Wheatstone bridge 14 are all 15kΩ.

The Wheatstone bridge 14 is connected to both ends of the resistance layer resistor 13, the other two terminals of the Wheatstone bridge 14 are connected to a constant external voltage, and the voltage of the voltage source 15 is 5 volts; the sinusoidal light momentum excitation 19 acts on the nanobeam 12 On the upper and lower surfaces, the photon movement momentum drives the vibration of the nanobeam 12. When the nanobeam 12 vibrates, the resistance value of the resistance layer 13 of the nanobeam changes. The resistance change causes the current signal in the Wheatstone bridge 14 circuit to change, and the current signal is detected. The change of the vibration frequency of the nanobeam 12 can be detected.

The nanobeam 12 is forced to vibrate under the action of the alternating light momentum excitation 19, and the resistance value of the resistance layer resistance 13 pasted on the root of the nanobeam 12 changes, and the signal can be output by using the Wheatstone bridge 14 circuit, and the signal is passed through the signal amplifier 16 After zooming in, spectrum analysis can be performed to obtain vibration time domain and frequency domain vibration information images, and vibration parameters such as vibration amplitude and vibration frequency. Change the light momentum excitation 19 generating device to drive the motor 8 speed, and the light excitation frequency changes accordingly. When the nanobeam 12 resonates, the output current signal value is the largest, and the resonance vibration frequency of the nanobeam 12 can be detected by measuring the peak value of the voltage change, and the nanometer beam 12 can be obtained by calculation. The size of the additional mass attached to the end of the beam 12 achieves the purpose of measuring the molecular mass.

The monochromatic light is vertically irradiated on the upper surface of the nanobeam 12, and the light momentum excitation force generated by the light radiation passing through the light hole 18 is In the formula, P is the power of the incident light passing through the light hole 18, α is the force efficiency of the incident light, n is the refractive index of the surrounding medium, c is the speed of light, k is the number of light holes on the disk, ω is the rotation speed of the disc.

When the nano-beam 12 resonates, the disc speed ω value is measured when the resonance is obtained, and the quality of the nano-particles is in, ρ is the linear density of the nanobeam 12, E is the modulus of elasticity of the nanobeam 12, l is the length of the nanobeam 12, b is the width of the nanobeam 12, and h is the height of the nanobeam 12.

Example 1: Monochromatic light is irradiated vertically on the upper surface of the nanobeam 12, the power P of the incident light passing through the light hole 18 is 1×10 ^-6 w, the force efficiency α of the incident light is 0.8, and the refraction of the surrounding medium The rate n is 1, the speed of light c is 3×10 ⁸ m/s, the number k of light holes on the disk is 1256, the linear density of the nanobeam 12 is 9.32×10 ^-9 kg/m, and the elastic mode of the nanobeam 12 is The volume E is 170 GPa, the length l of the nanobeam 12 is 40 μm, the width b of the nanobeam 12 is 5 μm, and the height h of the nanobeam 12 is 0.8 μm. The amplitude of the excitation force generated by the light momentum generated by the light radiation passing through the aperture 18 is 2.0×10 ⁻³ nN.

When the nanobeam 12 resonates, it is measured that the rotation speed of the disk is 1700 revolutions per second, and the mass of the nanoparticle 5 is 2.7358×10 ⁻¹⁵ kg.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. A photomomentum-excited nano-beam mass measuring device, comprising a sinusoidal photomomentum-like excitation (19) generating device and a micro-mass detection device. The photomomentum excitation (19) generating device consists of two upper disks (3), lower disks (4), upper lasers (17), lower lasers (6), and shafts fixed on the same shaft (7). (7), the upper bearing (2), the lower bearing (9), the driving motor (8) and the fixed end (1), the upper end and the lower end of the shaft (7) are respectively equipped with a bearing, and the lower end of the shaft (7) is hinged to a drive The motor (8), the driving motor (8) drives the shaft (7) to rotate; the radius of the upper disc (3) and the lower disc (4) is 12mm, and the upper disc (3) and the lower disc (4) are along the A square light hole (18) of equal area is opened at an equal distance from the axis. The side length of the square light hole (18) is 5 μm, and the side length is far greater than the wavelength of light. The distance between two adjacent light holes (18) is equal, and the distance between two adjacent light holes (18) is four times the width of the light hole (18). The distance is twice the width of the clear hole. Upper laser (17) and lower laser (6) are fixed on the base (11), when the monochromatic light (10) of upper laser (17) and lower laser (6) irradiates respectively The light hole (18) drives the motor (8) to drive the shaft (7) to rotate, which can generate light momentum excitation (19) similar to a sinusoidal distribution, and excite the nanobeam to vibrate. 2. according to the described device of claim 1, it is characterized in that: the monochromatic light is vertically irradiated on the upper surface of the nano-beam (12), and the photomomentum excitation force produced by the optical radiation through the light hole (18) is In the formula, P is the power of the incident light passing through the light hole (18), α is the force efficiency of the incident light, n is the refractive index of the surrounding medium, c is the speed of light, and k is the number of light holes on the disk , ω is the rotational speed of the disk. 3. according to the described device of claim 1, it is characterized in that: when the nano-beam (12) resonates, the disc speed ω value is measured when obtaining the resonance, and the quality of the nano-particles is in, ρ is the linear density of nano-beam (12), E is the modulus of elasticity of nano-beam (12), l is the length of nano-beam (12), the width of b nano-beam (12), h is the diameter of nano-beam (12) high.