Sound waves: sound source mechanical vibration

Ultrasound: exciting solid high-frequency machinery through strong gas or liquid Vibration can produce ultrasonic waves

Piezoelectric effect: mechanical energy → electrical energy

Inverse piezoelectric effect: electrical energy → mechanical energy

Speed: The distance that ultrasonic waves travel per unit time in a medium. m/s is the fastest in solids, followed by liquids, and the slowest in gases. As the temperature rises, the speed increases.

Frequency: the number of ultrasonic wave fluctuations per unit time, unit: Hz. The frequency range commonly used in rehabilitation medicine is: 800-3000kHz

Sound pressure: When ultrasonic waves propagate in a medium, the medium particles reciprocate near their equilibrium position, causing rhythmic density changes inside the medium. This density change forms a pressure change, that is, sound pressure. Positive pressure is generated in areas with dense particles, and negative pressure is generated in areas with sparse particles. Sound pressure is directly proportional to the frequency and amplitude of the ultrasonic wave, and inversely proportional to the acoustic resistance. The sound pressure produced by medium-sized ultrasonic waves on human tissue is about 3 atmospheres.

Strong voice

Longitudinal wave

degree of divergence

Acoustic resistance

Reflection: The smaller the incident angle of reflection, the smaller the reflection angle. The less the ultrasonic energy is reflected, the more efficient it is. The larger the incident angle, the larger the reflection angle, and the greater the ultrasonic energy loss. The smaller the difference in acoustic resistance between the two media, the smaller the energy reflection.

Refraction: The refracted ultrasonic energy is the difference between the incident energy and the reflected energy

Sound field: The spatial range in which ultrasonic waves propagate in the medium, that is, the area in which ultrasonic waves can act.

Near field area (sound beam is slightly converged), far field area (beam spread)

Influencing factors: (1) Medium: density, viscosity, thermal conductivity, sound speed, and frequency of the medium. (2) Frequency of sound speed: The higher the frequency, the stronger the medium’s ability to absorb ultrasonic waves, the worse the penetration ability of ultrasonic waves in the medium, and the smaller the penetration distance.

Half-valence layer: The distance that ultrasonic waves travel through the medium when the sound energy is attenuated to half of the original energy.

Interference phenomenon: (1) The superposition of the resulting vibrations when several wave sources meet during wave propagation (2) The two waves have the same frequency, the same vibration direction, and the same propagation direction.

standing wave

When ultrasonic waves propagate in the medium, they cause rhythmic density changes inside the particles, resulting in pressure changes and subtle changes in cell volume, which is called cell massage.

"Cell massage" is the most basic mechanism of ultrasound treatment of diseases

At the same dose, bone and connective tissue produce the most heat, while fat and blood produce the least.

Enhance local blood circulation and nutritional metabolism. Reduce tension and sensory nerve excitability. Relieve spasms and pain

When ultrasonic waves act on the human body, the body absorbs sound energy and generates heat energy.

Cavitation: Changes cell membrane permeability and promotes tissue repair. Change nerve electrical activity and relieve pain.

Thixotropy: Treatment of diseases related to tissue dehydration

Diffusion: Improve biofilm permeability

Adjust pH: Increase, relieve pain

Depolymerization: regulates enzyme activity

Direct treatment: moving method, fixed method

Indirect treatment: underwater method, assistive device therapy