The role of ultrasound and the principle?

Ultrasonic waves of high frequency, short wavelength, he can be like light along the straight line propagation, so that we have the possibility to a certain direction has been determined on the launch of ultrasound waves, sound waves are longitudinal waves, can be smooth in the human body tissues. Ultrasound is a longitudinal wave that travels smoothly through the body's tissues. Ultrasound waves are reflected when they meet different media.

Sound wave is one of the categories of sound, belongs to the mechanical wave, sound wave is a kind of longitudinal wave that can be perceived by the human ear, and its frequency range is 16Hz-20KHz. when the frequency of the sound wave is lower than 16Hz, it is called infrasound, and higher than 20KHz, it is called ultrasonic sound wave.

In the world, ultrasound is widely used in diagnostics, therapeutics, engineering, biology and other fields. Safari home ultrasound therapy machine belongs to the use of ultrasound therapy.

(A) engineering applications: underwater positioning and communications, underground resource exploration, etc.

(B) biological applications: shear macromolecules, bioengineering and treatment of seeds, etc.

(C) diagnostic applications: A-type, B-type, M-type, D-type, dual-performance and color ultrasound, etc.

(D) therapeutic applications: physical therapy, cancer treatment, surgery, body lithotripsy, ultrasound, ultrasound, ultrasound, ultrasound, ultrasound, ultrasound, ultrasound, and so on. , surgery, extracorporeal lithotripsy, dentistry, etc.

The role of ultrasound

Glass parts . Glass and ceramic products descaling is a problem, if these items into the cleaning fluid, and then pass into the ultrasonic wave, the cleaning fluid's violent vibration impact on the items on the dirt, can be quickly cleaned.

While humans can't hear ultrasound, many animals can. They can use ultrasound to "navigate", hunt for food, or avoid hazards. You may have seen many bats flying back and forth in the courtyard at night in the summer, why do they fly in the absence of light and will not lose their way? The reason is that bats can emit ultrasonic waves of 2 to 100,000 Hz, which is like an active "radar station". Bats use this "sonar" to determine whether it is an insect or an obstacle in front of them. The mass of the radar can be tens, hundreds, or thousands of kilograms, and in some important properties of accuracy, anti-jamming ability, etc., it can be used to determine the presence of insects or obstacles in front of the flight. Bats are far superior to modern radiolocators in terms of accuracy, immunity to interference, and so on. In-depth study of the function and structure of various organs on the animal body, the knowledge gained will be used to improve the existing equipment, which is a new discipline developed in recent decades, called bionics.

We humans did not learn to use ultrasound until World War I, which is the use of the principle of "sonar" to detect targets in the water and their status, such as the location of submarines. At this time, people send a series of different frequencies of ultrasound into the water, and then record and process the reflected echoes, from the characteristics of the echoes we can estimate the detection of the object's distance, shape and its dynamic changes. The earliest use of ultrasound in medicine is in 1942, the Austrian doctor Dusik for the first time with ultrasound technology to scan the structure of the brain; later to the 60's doctors began to apply ultrasound to the detection of abdominal organs. Today, ultrasound scanning technology has become an indispensable tool for modern medical diagnosis.

The difference between sonar and radar

Sonar through ultrasound

Radar through radio waves

Medical ultrasonography works on the principle of some similarity with sonar, that is, ultrasound waves are launched into the body, and when it meets the interface in the body will be reflected and refracted, and in the human body tissue may be absorbed and attenuated. Because the shape and structure of various human tissues are not the same, so its reflection and refraction and absorption of ultrasound waves to different degrees, doctors are reflected by the instrument through the wave form, curve, or image characteristics to identify them. In addition, combined with anatomical knowledge, normal and pathological changes, can be diagnosed whether the organs examined are diseased.

There are different forms of ultrasound diagnostic methods currently used by doctors, which can be categorized into four main types: type A, type B, type M and type D. The most common types of ultrasound are type A, type B, type M and type D.

Type A: It is a method of displaying the characteristics of tissues by waveforms and is mainly used to measure the diameter of an organ to determine its size. It can be used to identify physical characteristics of the tissue, such as the presence of substance, fluid or gas.

Type B: A flat graphic representation of the tissue being examined. During the examination, the reflected signals from the human body interface are first transformed into points of light of varying intensity, which can be displayed on a fluorescent screen. This method is intuitive, reproducible, and can be used for before-and-after comparisons, so it is widely used in the diagnosis of obstetrics and gynecology, urology, digestion, and cardiovascular system diseases.

M-type: it is a method used to observe temporal changes in the activity interface. It is most suitable for checking the activity of the heart, and the dynamic change of its curve is called echocardiography, which can be used to observe the position, activity state, and the condition of the structure of each layer of the heart, etc. It is mostly used to assist the diagnosis of cardiac and large-vessel epidemics.

Type D: It is an ultrasound diagnostic method specialized in detecting blood flow and organ activity, also known as Doppler ultrasound diagnostic method. It can determine whether the blood vessels are open, whether the lumen is narrowed or occluded, and the location of lesions. The new generation of D-mode ultrasound can also quantify the flow of blood in the lumen. In recent years, scientists have developed a color-coded Doppler system, which can show the direction of blood flow in different colors under the indication of the anatomical landmarks of the echocardiogram, and the shade of the color represents the flow rate of the blood. Now there are also three-dimensional ultrasound visualization, ultrasound CT, ultrasound endoscopy and other ultrasound technology continues to emerge, and can also be used in conjunction with other examination instruments, so that the diagnostic accuracy of the disease is greatly improved. Ultrasound technology is playing a huge role in the medical community, with the progress of science, it will be more perfect, will be better for the benefit of mankind.

The study of ultrasound generation, propagation, reception, as well as a variety of ultrasound effects and applications of the acoustic branch called ultrasonics. Generate ultrasonic devices have mechanical ultrasonic generator (such as gas whistle, whistle and liquid whistle, etc.), the use of electromagnetic induction and electromagnetic effect of the principle of electric ultrasonic generator,

and the use of piezoelectric crystal electrostriction effect and ferromagnetic material made of magnetostrictive effect of electroacoustic transducer.

Ultrasonic effect When ultrasonic waves propagate in the medium, due to the interaction of ultrasound and the medium, so that the medium undergoes physical and chemical changes, resulting in

a series of mechanical, thermal, electromagnetic and chemical ultrasonic effect, including the following four effects:

① Mechanical effect. The mechanical effects of ultrasound can contribute to the emulsification of liquids, liquefaction of gels and dispersion of solids. When the ultrasonic fluid medium to form a standing wave, suspended in the fluid of tiny particles due to mechanical forces and cohesion in the wave joints, the formation of periodic accumulation in space. When ultrasonic waves propagate in piezoelectric and magnetostrictive materials, they are induced by the mechanical action of the ultrasonic waves due to the induced electrode polarization and induced magnetization (see dielectric physics and magnetostriction).

②Cavitation. Ultrasound can produce a large number of small bubbles when acting on the liquid . One reason is that the local tensile stress in the liquid and the formation of negative pressure, the reduction in pressure so that the original dissolved in the liquid gas supersaturation, and escape from the liquid, becoming a small bubble. Another reason is the strong tensile stress to the liquid "torn" into a cavity, known as cavitation. Inside the cavity is liquid vapor or dissolved in the liquid of another gas, or even a vacuum. Due to the cavitation effect of the formation of small bubbles with the vibration of the surrounding medium and constantly moving, growing or suddenly burst. When the bursting of the surrounding liquid suddenly rushed into the bubble and produce high temperature, high pressure, at the same time produce a shock wave. With cavitation accompanied by internal friction can form a charge, and in the bubble due to discharge and produce luminescence. Ultrasonic treatment in the liquid in most of the technology related to cavitation.

3 thermal effect. Due to the high frequency of ultrasound, large energy, absorbed by the medium can produce significant thermal effects.

④Chemical effect. The role of ultrasound can promote the occurrence or accelerate some chemical reactions. For example, pure distilled water after ultrasonic treatment to produce hydrogen peroxide; dissolved nitrogen water after ultrasonic treatment to produce nitrous acid; dyes in aqueous solution after ultrasonic treatment will change color or fade. The occurrence of these phenomena is always accompanied by cavitation. Ultrasound can also accelerate the hydrolysis, decomposition and polymerization of many chemical substances. Ultrasound also has a significant effect on photochemical and electrochemical processes. A variety of amino acids and other organic substances in aqueous solution after ultrasound treatment, the characteristic absorption spectral band disappears and a uniform general absorption, which indicates that the cavitation effect of the molecular structure has changed .

Ultrasonic applications Ultrasonic effects have been widely used in practice, mainly in the following areas:

①Ultrasonic inspection. Ultrasonic wavelength is shorter than the general sound waves, has a better directionality, and can pass through the opaque material, this characteristic has been widely used in ultrasonic flaw detection, thickness measurement, distance measurement, remote control and ultrasound imaging technology. Ultrasonic imaging is the use of ultrasound to present the internal image of opaque material technology. The ultrasonic waves from the transducer through the acoustic lens focused on the opaque specimen, the ultrasonic waves transmitted from the specimen carries the information of the illuminated part (e.g., the ability of reflection, absorption and scattering of acoustic waves), through the acoustic lens convergence in the piezoelectric receiver, the resulting electrical signals into the amplifier, the use of scanning systems can be the opaque specimens the image of the fluorescent screen. The above device is called an ultrasound microscope. Ultrasound imaging technology has been widely used in medical examination, in the microelectronic device manufacturing industry is used to check the large-scale integrated circuits, in materials science is used to show the different components of the alloy in the region and grain boundaries and so on. Acoustic holography is an acoustic imaging technique that utilizes the interference principle of ultrasound to record and reproduce three-dimensional images of opaque objects, the principle of which is basically the same as that of holography of light waves, except that the means of recording are different (see holography). The same ultrasonic signal source is used to excite two transducers placed in a liquid, which emit two coherent beams of ultrasound: one beam passes through the object under study and becomes the object wave, and the other beam serves as the reference wave. The object wave and the reference wave are coherently superimposed on the liquid surface to form an acoustic hologram, which is illuminated by a laser beam to obtain a reproduced image of the object by utilizing the diffraction effect produced by the laser light when it is reflected on the acoustic hologram, and is usually observed in real time with a video camera and a television set.

②Ultrasonic processing. The use of ultrasound mechanical effect, cavitation, thermal and chemical effects, can be ultrasonic welding, drilling, crushing of solids, emulsification, degassing, dust removal, pot scale, cleaning, sterilization, chemical reactions and biological research, etc., in the industrial and mining industry, agriculture, medical and other sectors to obtain a wide range of applications.

3 basic research. Ultrasonic action in the medium, in the medium to produce acoustic relaxation process, acoustic relaxation process is accompanied by energy in the molecules of the respective electrical degree of transport between the process, and in the macroscopic manifestation of the absorption of acoustic waves (see acoustic waves). The properties and structure of matter can be explored through the law of absorption of ultrasound by matter, and research in this area constitutes the acoustic branch of molecular acoustics. The wavelength of ordinary sound waves is much larger than the atomic spacing in solids, which can be treated as a continuous medium under these conditions. But for the frequency of 1012 Hz above the special ultrasonic waves, the wavelength can be compared with the atomic spacing in the solid, this time the solid must be treated as having a spatial periodicity of the dot matrix structure. The energy of the dot matrix vibrations is quantized and is called a phonon (see physics of solids). The action of ultrasound on solids can be summarized as the interaction of ultrasound with thermal phonons, electrons, photons, and various quasiparticles. The study of the laws of generation, detection, and propagation of ultrasound in solids, as well as the study of acoustic phenomena in the quantum liquid, liquid helium, constitutes a new field of modern acoustics -

Sound waves are one of the classes of sound that belongs to the category of mechanical waves, and acoustic waves are refers to a longitudinal wave that can be perceived by the human ear, with a frequency range of 16Hz-20KHz. when the frequency of a sound wave is lower than 16Hz it is called an infrasound wave, and when it is higher than 20KHz it is called an ultrasonic sound wave.

Ultrasonic waves have the following characteristics:

1) Ultrasonic waves can be effectively propagated in gases, liquids, solids, solid melts and other media.

2) ultrasound can transmit very strong energy.

3) ultrasound will produce reflection, interference, superposition and *** vibration phenomenon.

4) ultrasound propagation in liquid media, can produce strong impact and cavitation phenomenon at the interface.

Ultrasonic waves are a member of the large family of sound waves.

Sound waves are a form of propagation of the state of mechanical vibration (or energy) of an object. Vibration is the back-and-forth motion of a mass of matter near its equilibrium position. For example, when a drum is struck, it vibrates up and down, and this state of vibration propagates in all directions through the air medium, which is a sound wave.

Ultrasonic waves are sound waves whose vibration frequency is greater than 20 kHz, and which cannot be heard or felt in the natural environment.

The concept of ultrasound therapy:

Ultrasonic therapy is an important part of ultrasound medicine. Ultrasound therapy when the ultrasound energy on the human body lesions, in order to achieve the purpose of treatment of diseases and promote the recovery of the body