Ultrasonic is a sound wave with a frequency higher than 20000 Hz. It has good directivity, strong penetrating ability, easy to obtain concentrated sound energy, and spreads long in water. It can be used for distance measurement, speed measurement, cleaning, welding, and gravel. , Sterilization, etc. There are many applications in medicine, military, industry, and agriculture. Ultrasound gets its name because its lower frequency limit is greater than the upper limit of human hearing.
Scientists call the number of vibrations per second the frequency of sound, and its unit is hertz (Hz). The frequency of sound waves that our human ears can hear is 20Hz-20000Hz. Therefore, we call sound waves with a frequency higher than 20000 Hz as "ultrasound." The frequency of ultrasound usually used for medical diagnosis is 1 MHz-30 MHz.
Common application scenarios of ultrasounic:
1. Cell fragmentation
Ultrasonic cell disruption has the advantages of simple operation, good repeatability, and time saving, and is mostly used for microbes and tissue cell disruption. Ultrasonic frequency is higher than 15-20KHz, forming a cavitation effect in the bacterial suspension, causing the cells to vibrate sharply and causing rupture, which is used to extract cell contents, such as: enzyme preparation from E. coli.
2. Ultrasonic chemical synthesis
During the cavitation effect of ultrasonic waves, air bubbles generate high temperatures up to 5000K and pressures greater than 200MPa. This becomes the energy source for ultrasonic chemical synthesis, and this energy can be used to synthesize nanoparticles on the surface of some particles.
3. Ultrasonic pharmaceutical
1) Dispersion of pharmaceutical substances for injection-disperse the mixture of phosphate esters, cholesterol and syrup through ultrasonic dispersion to obtain smaller particles for intravenous injection
2) Herbal medicine extraction——Using ultrasonic to break plant tissues, accelerate solvent penetration into tissues, and improve the extraction rate of effective ingredients of Chinese herbal medicines. For example, the leaching of alkaloids from cinchona bark usually takes more than 5 hours, and it takes only half an hour to disperse by ultrasonic.
3) Preparation of vaccines-after cells or germs are inactivated by means of ultrasonic dispersion, they are used for vaccine production.
4. Application of ultrasounic in cosmetics
The emulsification and dispersion effect of ultrasound on cosmetics forms smaller emulsified particles, which enables cosmetics to penetrate deeper into the skin layer, so that the skin can better absorb and play a better effect and effect. Ultrasonic dispersion is used to emulsify wax and paraffin without using emulsifiers, and to disperse the particles of oils such as lotion. The particle diameter can be below 1um.
5. Ultrasonic aging of wine-aging technology
The new wine has a spicy taste and poor taste. It needs a long time of storage and aging, which will produce a series of physical and chemical changes and association processes, which will make the spicy and irritating less spicy and soft, with increased aroma and harmonious taste. , Which is the maturity of raw wine. By using 17.5-22KHz ultrasonic treatment for 5-10min, the aging time of wine can be shortened by 1/3 to 1/2.
6. Ultrasonic cleaning
Ultrasonic cleaning is based on cavitation, that is, countless bubbles are rapidly formed in the cleaning liquid and quickly imploded, and the resulting impact will peel off the dirt on the surface of the object to be cleaned immersed in the cleaning liquid. With the increase of ultrasonic frequency, the number of bubbles increases and the impact of blasting decreases. Therefore, high-frequency ultrasonic is particularly suitable for cleaning small particles of dirt without damaging the working surface.
As people have a deeper understanding of the nature of ultrasound, ultrasound has made more and more contributions to mankind. It should be pointed out that if the application is improperly, ultrasound will have certain harm to the human body and organisms. For example, excessive ultrasound can cause tissue damage and opacity of the eye lens; too long irradiation of seeds will cause production reduction or death, which requires attention of.
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