CN113477283B

CN113477283B - Method for driving fluid to move by non-plasma metal photoinduced ultrasound and capturing device

Info

Publication number: CN113477283B
Application number: CN202110676166.5A
Authority: CN
Inventors: 王志明; 艾鑫; 林峰
Original assignee: Yangtze River Delta Research Institute of UESTC Huzhou
Current assignee: Yangtze River Delta Research Institute of UESTC Huzhou
Priority date: 2021-06-18
Filing date: 2021-06-18
Publication date: 2022-09-06
Anticipated expiration: 2041-06-18
Also published as: CN113477283A

Abstract

The invention discloses a method for driving fluid to move by non-plasma effect metal photoinduced ultrasound and a capturing device, wherein pulse laser is focused and then irradiates a substrate injected with non-plasma metal, the substrate absorbs the energy of the pulse laser, and the generated ultrasonic wave further drives the fluid to move macroscopically due to the fact that the photoacoustic effect generates the ultrasonic wave, and the quantity level of decimeter per second can be reached under 120 mW. Compared with the method for driving liquid by photoinduced ultrasound through gold, the laser flow control method adopted by the invention adopts metals such as iron, tungsten and the like with lower cost, and related devices have wider application in the biological aspect due to the biocompatibility of iron; in addition, due to the high melting point of the two metals, longer fluid flow times are exhibited after laser ablation than for gold implanted devices.

Description

Method for driving fluid to move by non-plasma metal photoinduced ultrasound and capturing device

Technical Field

The invention belongs to the technical field of laser-controlled fluid motion, and particularly relates to a method for driving fluid motion by non-plasma metal photoinduced ultrasound and a capturing device.

Background

For fluidic applications, such as microfluidic technologies, chemical microreactors and bioscience systems, methods of manipulating or driving liquids are important and fundamental requirements. Compared with the traditional method, the laser can achieve unique excellent properties such as higher strength at a micro scale due to excellent monochromaticity and good directional alignment property, and has unique advantages in the aspect of controlling liquid flow. The optical technology for fluid control has many excellent characteristics, such as no energy loss, no contact, no pollution, easy precise control in time and space and low manufacturing cost. However, most of the methods, such as the optically controlled fluid technology using light radiation pressure, or the thermo-capillary, electrophoresis and electro-optical wetting effects, have the problem that the flow velocity of the liquid driven by the optically controlled fluid technology is weak. The recently discovered photo-induced ultrasonic driving macroscopic fluid motion effect overcomes the limitation by combining the photoacoustic effect with the ultrasonic driving flow, and then, gold is injected into a quartz substrate through an ion injection technology to realize the real-time driving of a laser convection field, and any point on the quartz can be used as an emission point to generate jet flow, so that the technology has wider application prospect in the aspect of microfluidics, but still has a plurality of unsolved problems.

Firstly, gold is used as a noble metal, so that the cost is high, and the popularization and application aspects are limited; secondly, gold is not biocompatible, which limits the applications in living organisms such as painless injection; finally, although gold-implanted devices provide faster fluid driving speeds, their lifetime is very short and do not provide long-term flow fields.

Disclosure of Invention

The invention aims to provide a method for driving fluid to move by non-plasma metal photoinduced ultrasound and a capturing device, which can realize the durable service life of a flow field and have the characteristics of repeatability, wide application range, large application potential, higher flowing speed, long lasting time and the like.

In order to achieve the above purpose, the present invention provides a method for driving fluid movement by non-plasma metal photoinduced ultrasound, which comprises the following steps: the laser is focused and then irradiates a substrate injected with non-plasma metal ions, and the substrate absorbs the energy of the pulse laser, generates ultrasonic waves and drives fluid to perform macroscopic motion; wherein the non-plasma metal ions are iron or tungsten ions.

The beneficial effect who adopts above-mentioned scheme is: the photoacoustic effect occurs before the acoustic control fluid and determines the strength of the flow, and since the photoacoustic effect is a photothermal effect, a photoacoustic wave is generated to drive the fluid as long as the laser pulse can be absorbed and converted into heat. The ultrasonic waves can be generated by the thermal expansion of metal ions, the thermal expansion of surrounding water or transient water vapor around nanoparticles, when the temperature of a laser point is increased to be higher than a boiling temperature, the transient water vapor is generated, and higher local temperature caused by the thermal expansion of the water vapor can generate more steam and further generate stronger ultrasonic waves, so that the fluid can perform macroscopic motion under the condition of lasting flow field duration. Under the same control of irradiation conditions and absorbance, iron and tungsten have higher melting points, so that more lasting flow field duration can be provided under the same irradiation conditions, and lasting flow field service life is realized.

Further, the laser light was first emitted by a pulse laser having a wavelength of 532nm, a frequency of 1000Hz, and a pulse width of 150 ns.

Further, the focusing process is as follows: the laser was focused through a convex lens with a focal length of 5 cm.

The beneficial effect who adopts above-mentioned scheme is: the laser was focused on the substrate through a convex lens with a focal length of 5cm, and the liquid flow was observed without pretreatment time.

Further, the frequency of the pulse laser is 7.3-120 mW.

Further, the velocity of the fluid movement is directly proportional to the concentration of the injected metal.

The beneficial effect who adopts above-mentioned scheme is: by increasing the concentration of the injected metal, the absorbance of the substrate can be increased, and the flow rate can be increased effectively.

The device for capturing the movement of the non-plasma effect metal photoinduced ultrasonic driving fluid comprises a glass water pool, a substrate and a helium-neon laser, wherein the substrate and the helium-neon laser are positioned on two sides of the glass water pool, fluorescent particles are fully loaded in the glass water pool, and a camera is arranged outside the glass water pool.

Further, the wavelength of the he-ne laser is 632.8 nm.

The beneficial effect who adopts above-mentioned scheme is: 532nm pulsed laser is focused through a 5cm convex lens onto a substrate for non-plasma metal implantation, the substrate is placed in a glass water bath filled with fluorescent particles, a 632.8nm helium-neon laser is placed on the other side for illuminating the field of view, and after being elongated by a cylindrical lens, the flowing video is captured by a CCD camera on the side.

In summary, the invention has the following advantages:

1. the used experimental device is simple and easy to operate, the design structure cost is low, and the application is convenient; the threshold of power required for driving the fluid is low, and fluid motion can be realized at low power; under higher power, the maximum speed of decimeters per second can be reached;

2. the invention uses non-plasma metal, breaks through the metal which is limited to gold and generates the surface plasma resonance effect, and the selected substrate can generate the phenomenon of photoinduced ultrasonic driving fluid as long as the substrate has high enough absorbance, thereby providing wider selection for the application in the future;

3. the driving speed of the invention is greatly improved by increasing the concentration of the injected metal, which provides an experimental basis for the high-speed application of the invention;

4. the invention uses iron and tungsten as ion implantation metal, has low cost, strong continuous stability of flow field, wide application range and huge application potential, such as application in biology;

5. by the method provided by the invention, under the high-power pulse laser of 120mW, the maximum speed of the liquid driven by the laser flow control device injected by iron can reach 13.6 cm/s.

Drawings

FIG. 1 is a schematic view of an experimental apparatus according to the present invention;

FIG. 2 is a power threshold of a fluid produced by irradiating an iron-implanted quartz substrate with a pulsed laser at 532nm, a frequency of 1000Hz, and a pulse width of 150 ns;

FIG. 3 is a macroscopic view of an iron and gold injection sample of the same concentration gradient, uv-vis spectrum compared to maximum velocity at 30 mW;

FIG. 4 is a comparison of the continuous stability of three metal flow fields of Fe, W and Au at the same power and the same initial speed;

figure 5 is a graphical representation of the maximum speed that can be achieved for an iron-infused quartz sample at 120 mW.

Detailed Description

The principles and features of this invention are described below in conjunction with embodiments, which are included to explain the invention and not to limit the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

As shown in fig. 1, the present embodiment provides a method for driving fluid movement by non-plasma metal photoinduced ultrasound, which includes the following steps:

(1) injecting iron ions into the quartz substrate to ensure that the transmissivity of the quartz substrate is 51%;

(2) adjusting the wavelength of a pulse laser to be 532nm, the repetition frequency to be 1000Hz and the pulse width to be 150 ns;

(3) focusing the adjusted pulse laser on the surface of the quartz substrate through a convex lens with the focal length of 5cm, filling fluorescent particles in the water pool for responding to the irradiation of a 632.8nm helium-neon laser at the other end to emit light, and placing a CCD camera on the side face of the water pool to realize the function of capturing and shooting a view field.

As shown in fig. 2, when the laser frequency is slowly increased to 7.3mW under the irradiation of the laser pulser, the CCD camera images a weak fluid motion, wherein the white dotted line in fig. 2 is the position of the substrate and the red dot is the fluorescent particles in the water pool. As shown in FIG. 5, under the irradiation of the laser pulser, when the laser frequency is increased to 120mW, the maximum speed that the iron-implanted quartz substrate can reach is 13.6cm/s, which breaks through the magnitude increase of centimeter per second in the prior art.

Test example 1

This test example was conducted in the same photo-induced ultrasonic-driven fluid motion test as the iron ion-implanted substrate, in which the iron-implanted sample was black in appearance and the gold was red in appearance, as shown in fig. 3(a), and the two samples were rapidly distinguished in this way. As shown in FIG. 3(b), 5X 10 was selected ¹⁶ /cm ² And 1X 10 ¹⁷ /cm ² Transmittance measurements were made at two concentrations of iron and gold. The quartz substrate in which gold was implanted showed a significant transmission drop in the short wavelength band due to the surface plasmon resonance effect in the vicinity of 532 nm. Since the absorption of gold is higher than that of iron, the gold-implanted quartz slide produced a stronger jet as shown in fig. 3(c) - (f). However, in fig. 3(c) - (f), the sample velocity for gold injection increases only slightly when the two metal concentrations are doubled, while the flow field velocity increases more than twice for the iron injected sample.

Test example 2

As shown in fig. 4, the present test example examined the relationship between the ion concentration and the speed of fluid movement by comparing the efficiencies of the driving fluids of different metals, including a comparative illustration of iron and gold and iron and tungsten. Fig. 4(a) and 4(b) show the transmission spectra of four injected samples, with the absorption of the iron and gold control being about 50% and the absorption of the iron and tungsten control being about 24%. Fig. 4(c) - (d) record velocity profiles of four samples over 30 minutes. It can be seen that gold is much faster than iron in the laser stream, but iron is more stable than gold, at the same light absorption and laser power. A quartz substrate implanted with iron requires a higher laser power to produce the same initial velocity flow field than a quartz substrate implanted with gold, but at this higher power the stability is higher than gold. Between iron and tungsten, iron is more rapid, but tungsten is somewhat more stable than iron. This is proportional to the melting points of the three metals.

While the embodiments of the invention have been described in detail in connection with the drawings, the invention should not be construed as limited to the scope of the patent. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.

Claims

1. A method for driving fluid motion by photoinduced ultrasound of non-plasma effect metal is characterized by comprising the following steps: the laser is focused and then irradiates a substrate injected with non-plasma metal ions, and the substrate absorbs the energy of the pulse laser, generates ultrasonic waves and drives fluid to perform macroscopic motion; wherein the non-plasma metal ions are iron or tungsten ions;

the laser is firstly emitted by a pulse laser, the wavelength of the pulse laser is 532nm, the frequency of the pulse laser is 1000Hz, the pulse width of the pulse laser is 150ns, and the frequency of the pulse laser is 7.3-120 mW; the substrate is a quartz substrate.

2. The method of claim 1, wherein the focusing comprises: the laser was focused through a convex lens with a focal length of 5 cm.

3. The method of non-plasma effect metallic photoinduced ultrasonic driven fluid motion according to claim 1, wherein: the velocity of the fluid movement is directly proportional to the concentration of the injected metal.