Ultrasonic suction destructor device

FIELD: medical engineering.

SUBSTANCE: device has ultrasonic surgical instrument manufactured as staged ampoule-type concentrator which cylindrical part of greater diameter is coupled with the ampoule-type part by means of a stage, is resonator fixed in sealed casing and has at least one electromechanical element of piezoelectric type with contact surfaces connected to power supply generator. The electromechanical element is mounted on the resonator end located oppositely with respect to the stage. The resonator is fixed in sealed casing by means of axial compression on the casing part. The force applied between the stage and outer contact surface of electromechanical element is equal to a=(0,35-0.65)λ, where λ is the wavelength of longitudinal elastic resonator displacement coincident wave.

EFFECT: reduced device weight; high surgical instrument fatigue strength.

2 cl, 1 dwg

 

The technical field to which the invention relates.

The device relates to medical technology and is used to perform surgical operations in a wide range of surgical treatment by a metered layer of destruction of diseased biological tissue with subsequent removal by aspiration. In addition to the destruction and aspiration probably stimulated by ultrasound introduction by diffusion in the depth of the body shown medicinal substances. The device can be used in all types of medical institutions, as well as in the field.

The level of technology

Known devices medical equipment for a similar purpose, for example [1]. They are characterized by the following signs consistent with the essential features of the claimed invention:

- include ultrasonic surgical instrument with the possibility of its connection to the generator power;

- a surgical instrument includes at least one Electromechanical element, typically a piezoelectric type, with contact surfaces, providing the opportunity given connection. Electric strength of the Electromechanical element leads to the necessity of placing it in a sealed enclosure;

at least part of the surgical instrument in the form of conc the ora (also used the term "ultrasonic transformer speed"), designed to increase the amplitude of elastic waves at the working end of the surgical instrument to the required size and characterized by the gain. The requirement of a sufficiently large gain while maintaining high-cycle fatigue strength in the highest degree satisfies the well-known [2, s-141] step-sealed hub comprising two cylindrical portion of larger and smaller diameters, and a transitional portion of the ampoule form with a step between it and the cylindrical portion of larger diameter.

In General, to ultrasonic surgical instrument serves as the need for its performance as an Electromechanical resonator with a given fundamental frequency of longitudinal elastic displacements f, coinciding with the frequency of the generator. Only when this requirement, it is effective as a destructor. The disadvantage is considered analogues is no evidence for this requirement.

The prototype of the invention is an Ultrasonic surgical instrument" [3], characterized by the sign of its performance as a half-wave mechanical resonator is identical with the substantial equivalent characteristic of the present invention (see description of the invention [3], section "Information regarding the possibility of carrying out the invention").

Not the remains of the prototype due to the design of the resonator. Electromechanical element, which is part of the resonator, is located in the middle of the resonator; the node of the standing wave of the elastic displacement occurs at the mid-plane Electromechanical element. Mounting the resonator to the body in the form of an annular membrane, by necessity, does not coincide with the location of the Electromechanical element, whereupon the specified amplitude of the standing wave in the mounting area is finite. The consequence of this is the transfer of vibrations from the resonator to the body, the occurrence of losses of ultrasonic power and danger for the operator.

Eliminating these factors reach by increasing the mass of the body to a value of at least 1.25 times the mass of the resonator, which is a disadvantage.

Another disadvantage is due to the mounting of the resonator to the housing by an annular membrane at the free end of the resonator. This is the cause of the Flexural oscillation antinode of the bending stresses in the plane of the membrane, which leads to a weakening of its fatigue strength and also to losses of ultrasonic power.

The present invention is free from the above disadvantages.

Disclosure of inventions

The invention is directed to the elimination of losses ultrasonic power due to its transmission to the housing of the surgical instrument and the occurrence of Flexural stake is any resonator, leading to the weakening of the fatigue strength of the element attaching the resonator to the tool body.

The technical result of the invention is to reduce hull weight while maintaining safety for the operator and the increase in high-cycle fatigue strength of the device. In terms of violations of the resonance between the resonator and the oscillator, for example, when a significant mechanical load on the tool, the possibility of receiving the error signal.

The idea of the invention consists in performing a surgical instrument in the form of the step, such as step-ampoule, a hub, a cylindrical portion of larger diameter which contains the electro-mechanical elements and is half-wave electro-mechanical resonator at a given frequency longitudinal elastic displacements. Unlike the prototype, the cavity is made with the possibility of education in it standing wave longitudinal elastic displacements with an antinode in the middle of the plane and with nodes at the ends, that is, the new location of one of the Electromechanical elements. It is located on the opposite stage of the end of the resonator. The resonator is fixed in an airtight housing by axial compression. The compressive force is applied on the distance between the step of the stepped hub about iopological relative to the stage surface of the Electromechanical element. Thus aspire to a specified distance (dimension a) was equal to half the length of the mentioned waves.

This aspiration perform structurally as follows. It is known that the wavelength of longitudinal elastic waves in the medium is determined by the equation:

where

λ - the length of the specified wavelength;

E - young's modulus of the environment;

ρ - density environment;

f is a given oscillation frequency.

For a heterogeneous environment, with the specified parameters E and ρ are the effective values of and are determined by individual table settings component heterogeneous environment, taking into account their relative quantitative content in the environment, known to the calculated ratios. In this case, heterogeneous environment is the composite material of the resonator, and its components are included in the metal, piezoelectric and possibly dielectric parts. The axial dimensions of the piezoelectric and dielectric parts specified as components. Thus, the accomplishment of the stated aspirations

a=0,5 λ, (2)

where a is the size specified, is to define the calculation of the overall axial size of the metal parts of the resonator, taking into account the fact that the axial deformation when compressed sufficiently small compared with the dimension.

Of course, in a real device R is the equality (2) can not be maintained accurately. Therefore, the numerical coefficient set within 0,35-0,65. In this range the device is operational, and technical result is achieved, however, at the boundaries of the range quality, naturally, is reduced.

So, these new signs: the specified location of one of the Electromechanical elements and fastening cavity by axial compression in a sealed housing with maintaining size and within the specified limits, eliminate the invalid value transmission of ultrasonic power on the body, which removes the restriction on the minimum value of the mass body. The latter is now determined only by the requirement hull strength required for compression of the cavity and, with appropriate choice of material, such as ultra-light alloy IIR-2, significantly less than the mass of the resonator.

Due to these distinctive characteristics in relation to the bending instability of the resonator is a compressed rod, for which the critical force is equal to the sum of the forces of static and dynamic compression. From the nature of the dynamic compression should be that associated with the critical power of the length of the rod should be considered as the value of 0.5. Our analysis based on the known relation for the stability of elastic systems [4, p.124-126] leads to a value

where

and - the specified size;

D - dia is the Tr cavity;

E - its effective young's modulus;

σkrcritical for the occurrence of bending instability compressive stress due to the mentioned critical force. Equating σkrto well-known extreme voltage high-cycle fatigue strength, receive critical for the occurrence of the bending instability of the relationin order of magnitude equal to 10-102.

In practice, for the proposed device, the ratio is always less than 10, so that the appearance of the bending instability is excluded.

From the above it follows that the claimed total technical result of the invention is achieved; thus eliminating the weakened against fatigue resistance element is a membrane - opens the possibility when designing implement the principle of ravnopravnosti products. In this case, the product is characterized by high-quality performance, superior known from the prior art: reliability, durability, weight and size parameters, the efficiency of destruction.

The purpose of the invention specified in the particular case of violation of the resonance is the following. It is known that the electrical voltage generated in the piezoelectric capacitor is proportional to the mechanical strain in the piezoelectric material. In resonance e is tromechanical resonator with supply generator, that is, in the case that their frequencies, the node of the standing wave mechanical stress is in the middle plane of the resonator. Here is placed the average extra flat plane of the piezoelectric capacitor, for example, similar to the piezoelectric Electromechanical element. In resonance AC voltage on its potential to the plate tends to zero. In violation of the resonance, for example, due to changes in the fundamental frequency of the resonator during operation of the surgical tool under load, the nodal stress is shifted along the axis. This leads to an increase in AC voltage. This voltage is used as the error signal for adjusting the frequency of the oscillator, which greatly simplifies this task. This achieves the technical result in the particular case of carrying out the invention.

Thus, the invention is characterized by the following set of essential features that provide technical result in all cases of its use.

Ultrasonic destructor aspirator includes an ultrasonic surgical instrument with the possibility of its connection to the power generator.

The surgical instrument is made in the form of step, for example step-ampoule, hub, cilindric the sky portion of larger diameter which contains, at least one Electromechanical piezoelectric element type with the contact surfaces, which allow connection. In this form, this cylindrical part of the hub together with Electromechanical elements represents the Electromechanical resonator with a given fundamental frequency of longitudinal elastic displacements.

The resonator is placed in a hermetically sealed enclosure.

These symptoms are known from the prior art and coincide with the signs of the prototype of the invention [3], except for the used type of step-sealed hub.

The invention is characterized by the following distinctive features.

At least one of the members of the Electromechanical resonator element is placed on the opposite stage of the stepped hub end of the resonator.

The resonator is fixed in an airtight housing by axial compression between the specified level and extreme in relation to the degree of the contact surface of the specified Electromechanical element.

The axial dimension of the resonator is 0,35-0,65 from the length of the standing wave of the longitudinal elastic displacement at a specified frequency.

In the specified particular case of the invention differs in that the resonator further comprises a flat piezoelectric capacitor with an average of plosko is d, perpendicular to the axis of the resonator, located in the middle of the specified size.

Brief description of drawings

The drawing shows an ultrasonic surgical instrument with devices connected to other systems ultrasonic destructor-aspirator. The drawing size is increased and proportional. Dan axial slit and view along a-A. the Specified size as mentioned in the previous section. In the drawing and in the text of the following section provides a special case of a single Electromechanical element, which does not contradict the claims.

The implementation of the invention

The main part of the ultrasonic destructor aspirator surgical instrument has two buildings: the outer casing 1 supply of operating fluid and aspiration of the degradation products of biological tissues (liquid fraction) and a sealed casing 2. These corps, together with a reinforced elements connect the external device 16 and 13 and separate supply and removal of liquid fractions in the operating zone of the separator 23, are fixed (necoleblaise) of the surgical instrument. They work together to form channels 4 supply and aspiration of liquid through the nozzle 13 with holes 26, connected to external system of cylinders, pumps and switches of the apparatus. With the help of the separator 23 is analy have individual outlets operating in zone 21. Side walls 6 and 27 of the channels formed by the outer surface of the sealed housing 2 and the outside part of the hub 22, are the surfaces of the heat sink in the liquid fraction.

Moving a surgical instrument is executed in the form of stepped concentrator of ultrasonic vibrations [2, s-141]; used the step-sealed hub with the highest high-cycle fatigue strength with the ability to achieve high gain. This hub includes two cylindrical portions, respectively, of a smaller diameter 20 with a working end 21 and more with 5 sealed part 22 between them. Typical of this hub is the presence of stage 19 between the sealed part 22 and a cylindrical portion of larger diameter 5. The magnitude of the gain is limited to high-cycle fatigue strength in the field of stage 19. To increase the strength of the step 19 is associated with the ampoule part 22 advanced fillet 24. Maintaining the principle of ravnopravnosti, this unit is adopted high gain equal to 20. Based on this value, the well-known formulas [2, s-137, table 3-5] defined the profile of the sealed part 22 and the ratio between the diameters and characteristic lengths of the hub. A cylindrical portion of larger diameter 5 contains edge is least two metal cylinder 7 and 10, and the cylinder 7 is made as one with the sealed part 22, which increases the strength of the hub in the field of stage 19. Between the cylinders 7 and 10 placed additional flat piezoelectric capacitor of the piezoelectric disk and the ring 9 with potential plate 8 between them, connected to an insulated wire 28 to the signal output 17 in standard sealed plug connector 16. Characterized by a cylindrical part also contains at least one Electromechanical piezoelectric element 11 consisting of two piezoceramic rings, electrically and mechanically in contact with the metal cylinder 10 and sleeve 12 with its outer surfaces. The inner surface of the piezoceramic rings are in contact with potential metal plate 18 is connected to the power output socket 16 (not shown) using an insulated wire 29.

New in the design of a surgical instrument, in particular, is the location of one of the Electromechanical elements: it is placed opposite the working end 21 end of the hub.

All these details are described cylindrical part, in addition to wires, collectively characterized as mentioned in the section "summary of the invention an" effective values PLO is con ρ and young's modulus E and are Electromechanical resonator longitudinal elastic waves with a given fundamental frequency f associated with the wavelength X and the specified effective values of E and ρ ratio (1). Electromechanical resonator 3 is placed in the hermetically sealed casing 2 and secured therein by axial compression between level 19 and the outer contact surface of the Electromechanical element 11. Thus the value of its axial dimension is maintained within the specified limits (0,35-0,65)λ. Except in the field of stage 19 of the resonator 3 is separated from the inner surface of the sealed enclosure 2 narrow (less than 0.25 mm) radial clearance 30.

This mounting of the resonator is also new. Axial compression of the resonator can be made hot by cold pressing sleeve 12 is heated in a sealed enclosure 2 with controlled force and a consequent reduction in the axial size of the sealed housing 2 when it is cooling. In this case, the temperature of the sealed casing 2 when the hot pressing is kept on the temperature level heat sterilized surgical tool during its operation. The pressing force control using the resulting electrical voltage potential to the plate 18 of the Electromechanical element 11, maintaining the requirement safely the th mechanical compressive stress to applied materials piezoceramics in a cold-tight casing 2. The resonator 3 is sealed in the hermetic casing 2 by means of a metal seal 25 and the stub 15 with solder 14, and the cap 15 has no mechanical contact with the sleeve 12. Just sealed the flap 15 standard sealed plug 16.

It is essential that the cavity 3, with the axial dimension within the specified limits, the mechanical contact with the hermetic housing 2 only in the planes of the step 19 and the contact at the surface of the Electromechanical element 11 with the sleeve 12. This set of features, along with the location of the Electromechanical element is new and provides for the achievement of the claimed technical result, in all cases the use of the device, which can be seen from the following description of the steps of a surgical instrument.

With appropriate choice of materials in the design of the resonator 3 is a high-q Electromechanical vibrating system characterized by effective parameters E and ρ and the fundamental frequency f, which in practice is always set. Effective parameters E and ρ calculated by the method of iterations on the ratios of (1), (2) and

where:

Enthat ρn, anvalue at the nth step of the iteration;

Li- set the axial dimensions of the parts of the resonator of the specified material is s: metals, piezoelectric materials and, possibly, dielectrics;

Eithat ρi- table parameters specified materials. Note that the adopted base frequency 44 kHz, and even more for lower frequencies, due to the higher metal content in the composition of the resonator, an iterative process quickly converges, so that satisfactory accuracy are on the first step of the iteration, the effective parameters used in equation (1)are slightly different from table-valued parameters for metal cylinders 7 and 10.

At a given fundamental frequency f of the resonator is a half-wave resonator with standing wave longitudinal elastic waves, characterized by the antinode of the longitudinal displacements in the middle and the nodes in the regions of the ends of the dimension. When using ustalosti durable and high-quality materials, such as titanium alloy VTZ-1 and piezoelectric CTS-23, sjpc-24 or CTS-300, the resonator at the selected frequency 44 kHz more than 102and the amplitude And longitudinal displacements at the node is characterized by a value of 10 μm. In the ideal case, when the equality (2), the amplitude of the longitudinal elastic displacements in the plane of attachment of the resonator is equal to zero. Coupled with the wave of a longitudinal displacement of the radial Poisson wave displacements with the antinode and the node in the same planes is blocked from germ is part of the housing radial clearance 30. In practice always the ratio of the length of the cavity to the diameter of the a/D is less than 10, so that the bending resistance is not broken, bending vibration does not occur. Obviously, ensuring the safety of the operator is not required to increase the mass of the device. In this device, the weight of the hull is structurally determined by the requirements of strength under static tension, paired with axial compression of the resonator. Given that this requirement is significantly weaker requirements for high-cycle fatigue strength of the resonator and applying materials with low density, such as ultra-light and durable alloy of magnesium-based IHH-2 with a density of 1500 kg/m3get the mass ratio of fixed to mobile system, a surgical instrument is about 0.25. Along with this due to the new design of the resonator elimination of the weakest in terms of strength of the element membrane, optionally loaded Flexural vibrations significantly increases high-cycle fatigue strength of the device. In the ideal case, when the equality (2), the claimed technical result of the invention is fully achieved.

We show that the technical result is achieved in the claimed range and equal to (0,35-0,65)λ. In this case, the location of the right (see drawing) of the node of the standing wave displacements are saved it is determined by the location of the Electromechanical element. The one on the left site on the limits of the specified range is offset relative to the plane of the stage on the value of l equal to plus or minus 0.15λ. The displacement amplitude in the plane is not equal to zero and iswhere a is the amplitude at the antinodes. Counting And equal to 10 μm, get to vibrations in the plane size of about 8 microns. Taking into account the dissipation in structural connections, these vibrations are transmitted to the outer casing with a factor of 0.3 to 0.5; the operator is exposed to fluctuations with an amplitude of not more than 4 μm, which is safe. So the claimed technical result is achieved on these limits, although, of course, the quality of the device is reduced.

In the particular case of the possible deviation of the fundamental frequency of the resonator from a given respectively adjust the oscillator frequency. As the Manager of this adjustment of the error signal using voltage arising on the potential of the plate 8 additional flat piezoelectric capacitor 9 when the deviation node of the standing wave mechanical stress from its mid-plane. This achieves the technical result of the invention in this particular case.

So, implementing the principle of ravnopravnosti design, on the basis of the invention achieve high mass-dimensional characteristics x the surgical instrument. At base frequency 44 kHz overall dimensions are: length 165 mm and a diameter of 45 mm with a total weight of less than 0.3 kg and the amplitude of the oscillations of the working end reaches 200 μm, which is specified frequency ensures the effectiveness of destruction, superior known from the prior art.

Sources of information

1. EN 2050152 C1, 20.12.1995. Ultrasonic surgical apparatus.

2. Don A.V., Keller O.K., Crates G.S. Ultrasonic electrotechnological installations. Energoizdat, 1982.

3. EN 2187278 C2, 20.08.2002. Ultrasonic surgical instrument.

4. Landau L.D., Lifshitz E.M. Theory of elasticity M.: Nauka, 1965.

1. Ultrasonic destructor aspirator containing an ultrasonic surgical instrument, made in the form of step, for example step-sealed hub, a cylindrical portion of larger diameter which is associated with the ampoule part through the stage resonator is fixed in a sealed housing, and includes at least one Electromechanical piezoelectric element type with contact surfaces, with the possibility of its connection to the power generator, characterized in that the Electromechanical element is placed on the opposite stage of the end of the resonator, the resonator is fixed in an airtight housing by axial compression in this case with the Eli, applied between the tread and the outer contact surface of the Electromechanical element, the size between the tread and the outer contact surface of the Electromechanical element is a=(0,35÷0,65)λwhere λ - the length of the standing wave of the longitudinal elastic displacements of the resonator.

2. Ultrasonic destructor aspirator according to claim 1, wherein the resonator further comprises a flat piezoelectric capacitor perpendicular to the axis of the resonator average plane located in the middle of the dimension.



 

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FIELD: medical engineering.

SUBSTANCE: device has ultrasonic surgical instrument manufactured as staged ampoule-type concentrator which cylindrical part of greater diameter is coupled with the ampoule-type part by means of a stage, is resonator fixed in sealed casing and has at least one electromechanical element of piezoelectric type with contact surfaces connected to power supply generator. The electromechanical element is mounted on the resonator end located oppositely with respect to the stage. The resonator is fixed in sealed casing by means of axial compression on the casing part. The force applied between the stage and outer contact surface of electromechanical element is equal to a=(0,35-0.65)λ, where λ is the wavelength of longitudinal elastic resonator displacement coincident wave.

EFFECT: reduced device weight; high surgical instrument fatigue strength.

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