The development of Ultrasonic Scalpel

Since the 1990 s, ultrasonic surgical application more and more widely in biomedical fields.The development of efficient and flexible ultrasonic scalpel has become a hot research field.The ultrasonic scalpel is mainly used in cataract emulsification, liver tumor attract, liposuction beauty, cut bone blood coagulation, etc.Because it has a high precision, less bleeding, no burns and fast recovery, have replaced the trend of the high frequency electricity knife, mechanical clamp.

Ultrasound in the human body will produce a series of physiological effects, mainly as cavitation, mechanical effects, thermal effects, thixotropic effects, dispersion effects. Different ultrasound surgery, often an effect dominated, with other effects.

Tiny bubbles in the liquid is usually called cavitation nuclei, under the action of ultrasonic cavitation nuclei volume will be changed dramatically. Cavitation nuclei are formed, oscillation, growth, contraction that crash, caused by a series of physical and chemical changes, called ultrasonic cavitation. When the collapse of cavitation nuclei within a very short period of time around the cavitation nuclei small space, high temperature and high pressure, accompanied by strong shock wave and jets, and thus tissue emulsification, fragmentation effect. Cavitation is selective, that is, its organizational fragmentation water and fat volume. Collagen-rich tissues such as blood vessels, nerves, ureters low water content, higher than that of the liver, cancer, spleen and other tissue water content is more difficult to crack. Selective use of ultrasonic cavitation effect can be safely cut the tumor, without damaging the liver blood vessels and nerve tissue. Phacoemulsification, fat, etc ,mainly based on cavitation.

Biological tissue elastic vibration in the sound intensity ultrasonic , its amplitude is proportional to the square root of the sound intensity. When the sound intensity increases to mechanical vibration organization beyond its elastic limit, the organization will be broken or crushed. This effect is called mechanical effects of ultrasound. Ultrasound bone saws, cutting soft tissue is mainly based on mechanical effects. Different biological tissues have different elastic limit, so different amplitudes cutting heads required. Soft tissue cutting, scalpel head required minimum amplitude of 40, when the head osteotomy required amplitude output 100 may reflect the size and power to match the quality of the sound output power tool is the main performance indicators ultrasonic knife.

Ultrasonic scalpel working principle is to use electrostrictive effect or magnetostrictive effect, the ultrasonic energy is converted to mechanical energy, by amplifying and coupling horn, work to promote human heads of local tissue radiation energy, thereby performing surgery treatment. Using electrostrictive effect, ultrasonic scalpel vibration system consists of a piezoelectric transducer, composed of horn, head of three parts. Piezoelectric sheet by the preload screws, the power supply of electrical energy into mechanical energy, horn by focused ultrasound energy to a small area enlarged up mechanical vibrations or displacement speed, its shape has an exponential type, ladder type, catenary linear and complex, such as different types. Acoustic radiation of the cutting tools, cutting the human tissue or emulsion and using negative pressure suction out off human body.

Magnetostrictive effect of ultrasonic scalpel vibration system includes a magnetostrictive transducer, composed of horn, head of three parts. Magnetostrictive material generally used nickel alloy. Nickel alloy produced by the transducer, the output amplitude is large, suitable for high load applications, such as bone and soft tissue cutting, and stable performance. But compared with the piezoelectric transducer higher prices. Currently less harmonic scalpel use this structure, the United States CUSA attract is one of them.