Ultrasonic transducer and ultrasonic treatment device having the same

Abstract

The present invention provides a transducer body (11) that generates ultrasonic waves and has a curved radiation surface (11a), and a transducer cover (12) that covers the radiation surface (11a) of the transducer body (11) and serves as an acoustic matching layer. The transducer cover (12) is shaped to fit the radiation surface (11a) of the transducer body (11). This provides an ultrasonic transducer that is highly durable and can deliver sound waves more stably to deeper areas.

Description

[Technical field]

[0001] The present invention relates to an ultrasonic transducer in which a transducer body that generates ultrasonic waves is covered with a transducer cover, and an ultrasonic treatment device having the same. [Background technology]

[0002] Conventionally, a device for treating dementia is known that includes multiple ultrasound probes, ultrasound transducers disposed on the ultrasound probes and transmitting unfocused ultrasound energy to the brain, and an ultrasound generator connected to the ultrasound probes (see, for example, Patent Document 1).

[0003] This device is configured to irradiate diseased areas such as the brain and heart with LIPUS (Low-Intensity Pulsed Ultrasound) and promote angiogenesis and neurogenesis by increasing the expression of endothelial nitric oxide synthase (hereinafter referred to as eNOS) and vascular endothelial growth factor (hereinafter referred to as VEGF). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 181991 Summary of the Invention [Problem to be solved by the invention]

[0005] However, while conventional ultrasound transducers are capable of irradiating the entire target area, namely the brain and heart, with a single or multiple transducers, it is difficult for the sound waves irradiated from the emission surface to reach deep areas with a constant pressure due to vibration modes and sound wave interference.

[0006] Furthermore, conventional ultrasonic transducers have problems in that the radiation surface has a special shape, making it vulnerable to shock, and the waterproof protective film applied to the surface is easily peeled off due to heat and shock.

[0007] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide an ultrasonic transducer that is highly durable and can deliver sound waves to deeper areas more stably. [Means for solving the problem]

[0008] In order to achieve the above object, in the present invention, the radiation surface of the vibrator body is covered with a cover that conforms to the curved shape of the vibrator body.

[0009] Specifically, in the first invention, A transducer body having a curved radiating surface for generating ultrasonic waves; a transducer cover that covers the radiation surface of the transducer body and serves as an acoustic matching layer; The transducer cover has a shape that fits along the radiation surface of the transducer body.

[0010] According to the above configuration, the radiating surface of the transducer body is curved, so the irradiated waveform spreads as it travels. The spread of sound inside the transducer cover is determined by Snell's law, but the material of the transducer cover is usually made of a solid such as a resin molded product, so the sound speed is faster than that of water or a living body, and the refractive index is large. As a result, the range irradiated from the transducer cover is irradiated from a wider surface than when there is no transducer cover. This allows for more constant irradiation. Furthermore, the transducer cover maintains the distance between the transducer body, which is a heat source, and the living body, etc., so the problem of surface temperature rise can also be reduced.

[0011] In the second invention, in the first invention, The shape of the radiation surface of the transducer body is a convex spherical surface.

[0012] Normally, the waves emitted from the irradiation surface of the vibrator body are considered to be a collection of point light sources with the irradiation surface as the reference, and if the radiation surface is a convex spherical surface, the sounds from the point light sources interfere with each other, creating areas where the sounds weaken or strengthen each other, resulting in an inconsistent sound field. However, with the above configuration, by covering the radiation surface with a vibrator cover, more consistent irradiation from a wide surface is possible.

[0013] In a third aspect of the present invention, in the first aspect of the present invention, The transducer cover has a constant thickness.

[0014] According to the above-mentioned configuration, there is no need to finely adjust the thickness of the cover, and manufacturing is easy.

[0015] In a fourth aspect of the present invention, in the third aspect of the present invention, When the wavelength of the material of the transducer cover is λ, The thickness of the transducer cover is Between λ / 8 and 3λ, and Excluding the range of ±λ / 40 for each of λ / 8, λ / 4, and λ / 2.

[0016] According to the above configuration, a resonant structure is formed, and by deliberately excluding the vicinity of the thickness (λ / 8, λ / 4, and λ / 2) at which maximum transmission is possible, a transducer cover that serves as an acoustic matching layer with little variation in irradiation as an ultrasonic transducer can be obtained. This is because it is possible to avoid the problem of sudden changes in irradiation energy caused by a slight deviation from the thickness at which the amplitude is maximum. If the thickness of the transducer cover is too thin, the effect of diffusion due to refraction becomes small, and a transducer cover thicker than λ / 8 is desirable in consideration of not only acoustic performance but also manufacturability and durability of the transducer cover. If the thickness is greater than 3λ, attenuation becomes too large, making it difficult to actually use.

[0017] In a fifth aspect of the present invention, in the first aspect of the present invention, The thickness of the transducer cover is not constant but varies.

[0018] According to the above configuration, the thickness of the transducer cover is not constant but is varied, so that the spread can be controlled appropriately.

[0019] In the sixth invention, The transducer cover is made of a material having an elastic modulus of 2000 MPa or more and 10000 MPa or less and a specific acoustic impedance of 1.5 MPa·s / m or more and 10 MPa·s / m or less.

[0020] According to the above configuration, the material of the transducer cover maintains a moderate elastic modulus, and the speed of sound is faster than that of water and living bodies, so that the refractive index is large and the range irradiated from the transducer cover is wider.

[0021] The ultrasonic treatment device of the seventh invention is An ultrasonic transducer according to any one of the first to sixth aspects of the present invention; and a system for supplying energy to the ultrasonic transducer for ultrasonic vibration.

[0022] According to the above configuration, for example, in an ultrasonic therapy device that can treat angina pectoris or dementia by increasing the expression of eNOS and VEGF, a constant sound pressure can be delivered to deep positions and the durability of the ultrasonic transducer can be increased. Effect of the Invention

[0023] As described above, according to the present invention, by covering the curved radiation surface of the transducer body with a transducer cover that serves as an acoustic matching layer having a shape that conforms to this radiation surface, an ultrasonic transducer that is highly durable and can deliver sound waves more stably to deep areas can be obtained. [Brief description of the drawings]

[0024] [Figure 1] 1 is a block diagram showing an overview of an ultrasonic treatment device having an ultrasonic transducer according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of an ultrasonic transducer. [Diagram 3]These are cross-sectional views of a vibrator body and a vibrator cover. FIG. 3(a) shows the case where the vibrator cover has a constant thickness, FIG. 3(b) shows the case where the vibrator cover is thinner in the center, and FIG. 3(c) shows the case where the vibrator cover is thicker in the center. [Figure 4] FIG. 13 is a diagram showing a simulation result of sound pressure level without a cover. [Diagram 5] 5(a) to (c) are diagrams showing simulation results of sound pressure levels corresponding to FIGS. 3(a) to (c), respectively. [Figure 6] FIG. 6(a) shows the simulation results when there is no cover, FIG. 6(b) shows the simulation results when the cover material has a wavelength of λ / 8, and FIG. 6(c) shows the simulation results when the cover material has a wavelength of λ / 3.4, where λ is the wavelength of the cover material. [Figure 7] 13(a) and 13(b) are diagrams showing the simulation results when covers having a thickness of λ / 4 and λ / 3.4 are attached, respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0026] 1 shows an overview of an ultrasonic therapy device 20 having an ultrasonic transducer 10 according to an embodiment of the present invention. The ultrasonic therapy device 20 is configured to transmit ultrasonic frequencies and irradiate the heart and brain using LIPUS, thereby treating angina, heart failure with preserved contractile function (HFpEF), and dementia caused by enhanced expression of eNOS and VEGF, although the uses of the ultrasonic transducer 10 are not particularly limited to the following.

[0027] To give an overview of this ultrasonic treatment device 20, in the ultrasonic treatment device 20, treatment information input by an operator 1, for example, treatment area 2 and patient information 3, is sent as a signal by a control unit 4 serving as a protocol management system within the ultrasonic treatment device 20, and after the transmission waveform is controlled by a transmission condition control unit 5 and the treatment protocol is controlled by a treatment protocol control unit 6, the signal is transmitted from a transmission unit 7, and the ultrasonic transducer 10 irradiates the brain from the treatment area 2 (for example, the head). The control unit 4, the transmission condition control unit 5, and the treatment protocol control unit 6 are, for example, composed of one or more microcomputers built into the ultrasonic treatment device 20.

[0028] When there are two or more ultrasonic transducers 10, the ultrasonic transducer is branched into a plurality of transducers at the transmitting unit 7, and each transducer is configured to irradiate ultrasonic waves from each of the ultrasonic transducers 10. For example, when the ultrasonic transducer 10 is used in a headset, a pair of ultrasonic transducers 10 is required on the left and right.

[0029] Information of the ultrasonic therapy device 20 is shown to the operator 1 by the display 8. Input to the ultrasonic therapy device 20 is performed by external input such as a keyboard or mouse, input by touch operation when the display 8 is a touch display, or insertion of a USB memory, etc.

[0030] 2, the ultrasonic transducer 10 used includes a transducer body 11, and the transducer body 11 is a diffusive transducer having a curved radiation surface 11a. Since the radiation surface 11a of the transducer body 11 has a curved shape, the irradiated waveform advances while diffusing.

[0031] As a result, it becomes possible to irradiate the entire target treatment site 2. For example, when the target is the brain, it is desirable for the irradiation range to spread with an angle of 77 degrees or more.

[0032] The ultrasonic transducer 10 has a transducer cover 12 for ensuring biological safety and for protecting the transducer body 11 from damage caused by impact. On the rear side of this transducer cover 12, there are a transducer housing 13 for covering the transducer body 11 and a transducer cable 14 for transmitting electricity to the transducer body 11. The transducer housing 13 may be integral with the transducer cover 12 or may be separate.

[0033] The vibrator body 11 can be, for example, a piezoelectric element such as a piezoelectric (PZT) element, a homopolymer (PVDF) of vinylidene fluoride (VdF), which is a fluororesin, barium titanate (BaTiO3), a relaxor-type piezoelectric single crystal (PIN-PmN-PT), or a capacitive micromachined ultrasonic transducer (CMUT), or a piezoelectric micromachined ultrasonic vibrator (PMUT) that uses a semiconductor process.

[0034] The frequency of the ultrasonic waves applied to the transducer body 11 is a frequency (number of cycles) that matches the frequency of the transducer body 11. The number of cycles is 1 cycle or more and 64 cycles or less, and preferably 24 cycles or more and 40 cycles or less. The average intensity (Ispta) within the pulse width is not particularly specified, but is preferably 720 mW / cm 2 Less than 150mW / cm 2 The following is the result.

[0035] The frequency of the transducer body 11 (the frequency at the resonance point or near the anti-resonance point) is, for example, 100 kHz or more and 10 MHz or less. The transducer body 11 is shaped like a convex sphere, and for example, as shown in FIG. 2, the radius R of the sphere is 10 mm or more and 30 mm or less, and the opening diameter D is 10 mm or more and 50 mm or less. A backing made of air, oil or a solid is provided on the rear side of the transducer body 11. The backing is disposed on the rear side of the transducer body 11, and serves to suppress the propagation of ultrasonic waves backward and to shorten the pulse width.

[0036] The material of the transducer cover 12 preferably has an elastic modulus of 2000 MPa or more and 10000 MPa or less, and a specific acoustic impedance of 1.5 MPa·s / m or more and 10 MPa·s / m or less.

[0037] Furthermore, if the wavelength of the material of the transducer cover 12 is λ, then the transducer cover 12 desirably has a thickness that is λ / 8 or more and 3λ or less, excluding the ranges of ±λ / 40 of λ / 8, λ / 4, and λ / 2.

[0038] Moreover, it is desirable that the shape of the transducer cover 12 conforms to the shape of the radiation surface of the transducer body 11 .

[0039] Examples of materials for the transducer cover 12 include synthetic resin materials such as PPE (polyphenylene ether), PBT (polybutylene terephthalate), ABS (acrylonitrile butadiene styrene), LDPE (low density polyethylene), PS (polystyrene), NORYL (registered trademark), Valox, Pebax, etc., composite materials of resin with carbon, graphite, metal, etc., etc.

[0040] The adhesive for bonding the rear surface of the transducer cover 12 to the radiation surface 11a of the transducer body 11 is preferably, for example, an epoxy or silicone adhesive.

[0041] The waterproofing of the transducer cover 12 may be provided by the material of the transducer cover 12 itself, or may be provided by applying a thin, acoustically non-destructive waterproof coating such as parylene (a series of polymers derived from paraxylene).

[0042] Regarding insulation, insulation is required at the patient contact portion of the transducer cover 12. For example, since the transducer body 11 has a GND (ground) layer on the surface, if the thickness of the transducer cover 12 is less than 0.4 mm or does not meet the withstand voltage of 1500 V, a separate insulating layer must be provided. For example, the insulating layer may be a polyvinyl chloride coating (PVC), a fluorine coating (ETFE), a polyethylene coating, a nylon coating, an epoxy coating, a PPS / PEEK coating, or the like.

[0043] --Example-- Usually, the waves irradiated from the radiation surface 11a of the vibrator body 11 are considered to be a collection of point light sources with the radiation surface 11a as the reference. In the case of the spherical convex shape of the vibrator body 11, the sounds from the point light sources interfere with each other and weaken or strengthen each other due to the shape, and ultimately the sound field is not constant.

[0044] In this embodiment, in order to solve this problem, the transducer cover 12 is attached to the radiation surface 11a of the transducer body 11.

[0045] The effect of the transducer cover 12 makes it possible to irradiate a wide range with a constant sound pressure level. The spread of sound inside the transducer cover 12 is determined by Snell's law (law of refraction), but the resin that is the material of the transducer cover 12 usually has a faster sound speed than water or living bodies (the sound speed of water is 1480 m / sec at 20°C), so the refractive index is large. As a result, the range irradiated from the transducer cover 12 is irradiated from a wider surface than when there is no transducer cover 12. This allows for more constant irradiation.

[0046] Fig. 3 shows examples of the shapes of the vibrator body 11 and vibrator cover 12. The vibrator cover 12 in Fig. 3(a) has a uniform, constant thickness, the vibrator cover 12' in Fig. 3(b) is thinner in the center, and the vibrator cover 12'' in Fig. 3(c) is thicker in the center.

[0047] Here, when the wavelength of the material of the transducer cover 12 is λ, the thickness of the transducer cover 12 in FIG. 3(a) is t=λ / 3.4, the thickness of the transducer cover 12' in FIG. 3(b) is t=λ / 4 in the center and λ / 2 at both ends, and the thickness of the transducer cover 12'' in FIG. 3(c) is t=λ×3 / 4 in the center and λ / 2 at both ends.

[0048] The results of the acoustic analysis are shown below. The acoustic analysis was performed with an overall dimension of 80 mm and a frequency of 500 kHz, and the sound pressure level dB was displayed in a color-coded linear scale.

[0049] Fig. 4 shows the simulation results of the sound pressure level without a cover, and Fig. 5(a) to (c) show the simulation results of the sound pressure level corresponding to Fig. 3(a) to (c), respectively. It can be seen that the sound pressure spreads more uniformly and widely to deeper places when the transducer covers 12, 12', and 12'' are present in Fig. 5(a) to (c) compared to the case without the transducer cover 12 in Fig. 4.

[0050] Furthermore, in order to achieve constant irradiation, the thickness of the transducer cover 12 must be at least a certain value. If it is too thin, the effect of diffusion due to refraction becomes small.

[0051] As a result of the acoustic analysis, when the wavelength of the material of the transducer cover 12 is λ, Figure 6(a) shows the case without a cover, Figure 6(b) shows the case with a cover material with a wavelength of λ / 8, and Figure 6(c) shows the case with a cover material with a wavelength of λ / 3.4. It can be seen that, despite the attenuation effect of the transducer cover 12, the case with the transducer cover 12 provides a more uniform sound pressure to a greater depth. It was also found that the case of λ / 3.4 in Figure 6(c), which is thicker than the case of λ / 8 in Figure 6(b), allows a higher level of sound pressure to be applied to a greater depth. This shows that a cover thicker than at least λ / 8 is desirable.

[0052] If the speed of sound is 2200 m / s and the transmission frequency is 500 kHz, then λ / 8 = 0.55 mm. In consideration of not only the acoustic performance but also manufacturability and durability of the transducer cover 12, a transducer cover 12 thicker than λ / 8 is desirable.

[0053] In addition to the spread due to the difference in sound speed, the transducer cover 12 is also thought to play a role as an acoustic matching layer. If the material used for the transducer cover 12 is a piezoelectric element, the impedance is about 30 MPa·s / m. If the sound speed of the transducer cover 12 is 2200 m / s and the density of the resin material is 1.2 g / cm 3 Then, the impedance is 2.6 MPa·s / m. On the other hand, the impedance of water is 1.44 MPa·s / m, a value between that of PZT and water. The transducer cover 12 reduces reflections at the boundary surface and unnecessary vibration modes, allowing for more efficient irradiation and is thought to contribute to a constant irradiation.

[0054] In a normal ultrasonic transducer, when an acoustic matching layer is attached, it is designed to have a thickness obtained by dividing the wavelength λ by 2×n (n is an integer) (for example, λ / 2, λ / 4, λ / 8, etc.) in order to increase the efficiency. This is because by designing with this thickness, the radiating surface of the matching layer becomes an open end, maximizing the amplitude.

[0055] However, even a slight deviation from this thickness can cause a problem of a sudden change in irradiation energy. This is due to manufacturing variability, and indicates that changes in thickness, frequency, and sound speed of the cover will cause variability in the device.

[0056] In this embodiment, the thickness is deliberately set to be outside the range that allows maximum transmission, so that the transducer cover 12 serves as an acoustic matching layer that reduces the variation in irradiation of the ultrasonic transducer 10 .

[0057] The method involves attaching a transducer cover 12 having a thickness that is λ / 40 or more away from the thickness of λ / 2, λ / 4, or λ / 8, for example, the value obtained by dividing the wavelength λ of the material of the transducer cover 12 by 2×n (n is an integer).

[0058] As an example, the simulation results when covers with a thickness of λ / 4 and λ / 3.4 are attached are shown in Figures 7(a) and 7(b), respectively. Although the difference in thickness is small at approximately λ / 23, it can be seen that there is a large difference in sound pressure level. This means that the λ / 4 has a resonant structure, and energy can be irradiated with extremely high efficiency at this thickness, but it also means that the change in thickness causes a sudden change in sound pressure level. Another feature is that when the thickness is λ / 3.4, there is less localized sound pressure difference compared to when the thickness is λ / 4.

[0059] Another problem is that the ultrasonic transducer 10 generates heat during transmission. Because the ultrasonic transducer 10 comes into contact with the patient, the heat generated by the transducer 10 may cause burns or other injuries. Although regulations stipulate an upper limit for the rise in surface temperature, the transducer cover 12 maintains the distance between the heating element (transducer body 11) and the living body, thereby reducing the problem of the rise in surface temperature.

[0060] Moreover, by making the thickness of the transducer cover 12 variable rather than constant, the spread can be controlled appropriately.

[0061] Furthermore, by deliberately setting the thickness outside the half wavelength, 1 / 4 wavelength, and 1 / 8 wavelength that are the usual design guidelines for acoustic matching layers, the effects of differences in thickness during the manufacturing process can be minimized.

[0062] Furthermore, because of its shape, the vibrator body 11 is characterized by its fragility when subjected to shocks, but by attaching vibrator covers 12, 12', 12'' made of a thick resin material with a high elastic modulus, the shock resistance can be improved.

[0063] The ultrasonic treatment device 20 of the present invention is a device that can widely output ultrasonic waves to the target area, and by irradiating the brain and heart with a predetermined transmission waveform, it can enhance the expression of eNOS and VEGF, promote angiogenesis and neurogenesis, and treat angina pectoris, heart failure with preserved systolic function (HFpEF), and dementia. The ultrasonic transducer 10 with a convex curved surface has a problem that the pressure is not constant at deep positions due to the vibration mode and interference of sound waves due to its special shape, but the shape of the transducer cover 12 of this embodiment follows the shape of the radiation surface 11a, and by attaching a resin that can be used as an acoustic matching layer to the radiation surface 11a, unnecessary vibration modes are suppressed and the effects of interference are mitigated, and constant irradiation to deeper positions is possible with the same output.

[0064] (Other embodiments) The present invention may be configured as follows with respect to the above embodiment.

[0065] That is, in the above embodiment, an example in which the ultrasonic transducer 10 is used in the ultrasonic treatment device 20 has been shown, but the ultrasonic transducer 10 can also be used in ultrasonic cleaners, ultrasonic humidifiers, ultrasonic dispersing / emulsifying devices, etc. Furthermore, the ultrasonic transducer 10 can also be used in fish finders, ultrasonic diagnostic devices, ultrasonic flow meters, ultrasonic level meters, etc.

[0066] In the above embodiment, the shape of the radiation surface 11a is a convex spherical surface that is approximately circular when viewed from above, but it may also be an ellipse, an oval, a rounded rectangle, a rounded square, or the like when viewed from above, having a convex curved surface.

[0067] It should be noted that the above-described embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its applications, or uses. [Explanation of symbols]

[0068] 1 Operator 2 Treatment area 3. Patient Information 4. Control section 5 Transmission condition control section 6 Treatment Protocol Control Unit 7. Transmitter 8. Display 10 Ultrasonic transducer 11 Transducer body 11a Radiation surface 12,12',12'' Transducer Cover 13 Transducer housing 14 Transducer cable 20 Ultrasonic treatment device

Claims

1. A transducer body having a curved radiating surface for generating ultrasonic waves; a transducer cover made of resin that covers the radiation surface of the transducer body and serves as an acoustic matching layer; the transducer cover has a shape that conforms to a radiation surface of the convex spherical surface of the transducer body, When the wavelength of the material of the transducer cover is λ, The thickness of the transducer cover is constant, λ / 8 or more and 3λ or less, and Except for the range of ±λ / 40 of λ / 8, λ / 4 and λ / 2 where the irradiation energy changes rapidly An ultrasonic transducer comprising:

2. If the thickness of the vibrator cover is less than 0.4 mm or does not satisfy the withstand voltage of 1500 V, an insulating layer is provided on the vibrator cover.

2. The ultrasonic transducer according to claim 1 .

3. The radius of the spherical surface of the vibrator body is 10 mm or more and 30 mm or less, and the opening diameter is 10 mm or more and 50 mm or less.

2. The ultrasonic transducer according to claim 1 .

4. A transducer housing that covers the transducer body is provided on the rear side of the transducer cover, The rear side of the vibrator body is provided with a backing made of air, oil or a solid.

2. The ultrasonic transducer according to claim 1 .

5. The transducer cover is integrally formed with the transducer housing.

5. The ultrasonic transducer according to claim 4.

6. The transducer cover is made of a material having an elastic modulus of 2000 MPa or more and 10000 MPa or less and a specific acoustic impedance of 1.5 MPa·s / m or more and 10 MPa·s / m or less.

2. The ultrasonic transducer according to claim 1 .

7. An ultrasonic transducer according to any one of claims 1 to 6; A system for supplying energy to the ultrasonic transducer for ultrasonic vibration. An ultrasonic treatment device characterized by:

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