Background
In recent years, the clinical application of ultrasound is no longer limited to image diagnosis, and the therapeutic effect of ultrasound in tumor and brain diseases is gradually a hot spot in modern medical research. For example, HIFU therapy is used for thermal tumor therapy by inducing transient hyperthermia using high intensity focused ultrasound to cause very rapid coagulation necrosis of tumor tissue; the focused sound field in the nerve regulation research can accurately stimulate the nerve nucleus, effectively regulate the nerve loop, and provide an important means for researching the pathogenesis and treatment of brain functions such as senile dementia, Parkinson, epilepsy, depression and the like.
Ultrasound neuromodulation utilizes ultrasound waves that propagate in tissue in pulses or continuous waves, thereby affecting the acoustic activity of the tissue through the mechanical or thermal effects of the ultrasound waves. The nerve of the stimulation part generates stimulation or inhibition effect by changing the ultrasonic frequency, pulse width, duration and ultrasonic intensity, thereby regulating the nerve function reversely and bidirectionally.
Current ultrasound neuromodulation is primarily for stimulating nerves using single-element focused ultrasound transducers. When the single-array-element focused ultrasonic transducer is used for ultrasonic nerve regulation and control, the nerve stimulation to different positions can not be realized under the condition of not changing the structural arrangement of the ultrasonic nerve regulation and control device, and the main reason is that the single-array-element ultrasonic transducer has a single focusing form and an unadjustable focusing depth, so that the flexibility of stimulating nuclei at different depths by ultrasonic nerve regulation and control is limited.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides an ultrasonic nerve regulation and control device, which aims to solve the problems that the focusing depth is not adjustable and the flexibility of ultrasonic nerve regulation and control stimulation of nuclear masses at different depths is limited.
The invention realizes that:
an ultrasonic nerve regulation and control device comprises a planar ultrasonic transducer, a Fresnel lens and an acoustic collimator, wherein the planar ultrasonic transducer, the Fresnel lens and the acoustic collimator are sequentially arranged, an emitting end of the planar ultrasonic transducer is used for emitting a planar ultrasonic signal, and the excitation frequency of the planar ultrasonic transducer is adjustable, wherein the focal length of the Fresnel lens is increased or decreased along with the increase or decrease of the frequency of the planar acoustic wave.
Optionally, the fresnel acoustic lens includes a plurality of concentrically arranged rings, a slit is formed between every two adjacent rings, and the width of each slit gradually decreases from inside to outside along the radial direction.
Optionally, the thickness of each of the rings is the same.
Optionally, the radius of the circular ring satisfies the following relationship:
wherein r isnRepresents the radius of the nth fresnel region; λ ═ c/f denotes the wavelength of the sound wave emitted by the planar ultrasonic transducer, c denotes the speed of sound, and f denotes the frequency of the sound wave emitted by the ultrasonic transducer; f denotes the preset focal length of the normal fresnel lens.
Optionally, the fresnel acoustic lens ring has a pi acoustic wave phase difference with the protrusions and grooves of the adjacent slits.
Optionally, the planar ultrasonic transducer has a sound emitting plane, the planar ultrasonic transducer emits the planar acoustic wave from the sound emitting plane, and the fresnel acoustic lens is disposed on the sound emitting plane.
Optionally, the ultrasonic transducer can adjust the frequency range of the sound waves to be 0.5-5 MHz.
Optionally, the ultrasonic transducer is a planar piezoelectric ceramic.
Optionally, the fresnel acoustic lens is made of photosensitive resin, acrylic material or medical silicone rubber.
Based on the invention, the planar ultrasonic transducer emits the planar sound wave, and the planar sound wave forms point focusing through the Nerphil acoustic lens, wherein the focal length of the Nerphil acoustic lens is increased or reduced along with the increase or decrease of the frequency of the planar sound wave, namely, the position of the planar sound wave forming point focusing through the Nerphil acoustic lens can be changed by changing the frequency of the planar sound wave, so that the ultrasonic focusing depth can be adjusted by adjusting the frequency of the planar sound wave emitted by the planar ultrasonic transducer, and a simple, convenient and flexible method is provided for regulating and stimulating brain nuclei at different depths by ultrasonic nerves.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides an ultrasonic nerve regulation and control device, which utilizes ultrasonic waves to stimulate the central nerve of a part in a pulse or continuous wave mode to generate a stimulation or inhibition effect so as to reversely and bidirectionally regulate the nerve function.
Referring to fig. 1 to 3, the ultrasound nerve modulation device includes a planar ultrasound transducer 100, a fresnel lens 200, and an acoustic collimator 300, wherein the planar ultrasound transducer 100, the fresnel lens 200, and the acoustic collimator 300 are sequentially disposed.
The transmitting end of the planar ultrasonic transducer 100 is configured to transmit a planar ultrasonic signal, where the planar ultrasonic signal is a parallel high-frequency ultrasonic beam, and the planar ultrasonic transducer 100 can adjust the frequency of the planar ultrasonic signal, that is, the planar ultrasonic transducer 100 can selectively transmit planar ultrasonic waves with different frequencies, rather than only fixedly transmit planar ultrasonic waves with one frequency; in the embodiment of the present invention, the range of the frequency of the sound wave which can be adjusted by the ultrasonic transducer is preferably 0.5 to 20MHz, for example, 0.6MHz, 0.7MHz, 0.8MHz, 1MHz, 1.2MHz, 1.5MHz, 1.8MHz, 2MHz, 3MHz, 4MHz, 5MHz, 6MHz, 8MHz, 10MHz, 12MHz, 15MHz, 10 MHz. The plane acoustic wave is diffracted after passing through the fresnel lens, and finally, a focusing acoustic field is formed at a side far from the plane ultrasonic transducer 100 along the propagation direction of the plane acoustic wave. Wherein the focal length of the fresnel acoustic lens 200 increases or decreases as the frequency of the planar acoustic wave increases or decreases.
Based on the ultrasonic nerve control device provided by the embodiment of the invention, the planar ultrasonic transducer 100 emits a planar sound wave, and the planar sound wave forms point focusing through the Fresnel sound lens 200, wherein the focal length of the Fresnel sound lens 200 is increased or decreased along with the increase or decrease of the frequency of the planar sound wave, namely, the position of the planar sound wave forming point focusing through the Fresnel sound lens 200 can be changed by changing the frequency of the planar sound wave, so that the ultrasonic focusing depth can be adjusted by adjusting the frequency of the planar sound wave emitted by the planar ultrasonic transducer 100, and a simple, convenient and flexible method is provided for stimulating brain nuclei at different depths by regulating and controlling the ultrasonic nerve.
It should be noted here that, in terms of the structural configuration of the fresnel lens 200, the focal length of the fresnel lens 200 may be increased as the frequency of the plane sound wave increases, or the focal length of the fresnel lens 200 may be decreased as the frequency of the plane sound wave increases.
Referring to fig. 1, in an embodiment of the present invention, the fresnel lens 200 includes a plurality of concentric rings, a slit is formed between every two adjacent rings, and the width of each slit gradually decreases from inside to outside along the radial direction. Alternatively, the ring may be made of photosensitive resin, acrylic material, or medical silicone rubber. In the present embodiment, the thickness of each circular arc is the same.
Specifically, the radius of the ring satisfies the following relationship:
wherein r isnRepresents the radius of the nth fresnel region; λ ═ c/f denotes the wavelength of the acoustic wave emitted by the planar ultrasonic transducer, c denotes the speed of sound, and f denotes the frequency of the acoustic wave emitted by the planar ultrasonic transducer 100; f denotes the preset focal length of the normal fresnel lens.
Wherein, the frequency of the sound wave emitted by the planar ultrasonic transducer 100 is 8MHz and the preset focus is set as the embodimentSince the depth F is 18mm, the acoustic wavelength λ is 0.1875mm, and the fresnel region radius is r1=1.8321mm,r2=2.5943mm,r3=3.1815mm,r4=3.6784mm,r5=4.1178mm,r6=4.5166mm,r7When the width of the fresnel lens 200 circle is 4.8846mm, the widths of the circles are: d1=2r1=3.6642mm,d2=r3–r2=1.8321mm,d3=r5–r4=1.8321mm。
Specifically, in the present embodiment, according to the fresnel diffraction principle, the phase difference between two adjacent regions of the fresnel lens is pi, and the acoustic wave phase difference between the annular portion of the fresnel acoustic lens 200 and the adjacent slit is pi, under which condition, the best ultrasonic focusing effect can be achieved.
The thickness of the annular part of the Fresnel lens can be calculated by the following formula:
wherein
Representing the phase difference between the annular part of the Fresnel lens and the adjacent slits, for which Fresnel lens
In the embodiment, the fresnel lens material is medical silicon rubber, and the sound speed c1 is 980m/s, and the thickness t of the fresnel lens is 0.27 mm.
Specifically, referring to fig. 2 and 3, the planar ultrasonic transducer 100 has a sound-emitting plane 110, the planar ultrasonic transducer 100 emits a planar acoustic wave from the sound-emitting plane 110, and the fresnel lens 200 is disposed on the sound-emitting plane 110, that is, the fresnel lens 200 is directly attached to the sound-emitting plane 110.
In the embodiment of the invention, the ultrasonic transducer is the planar piezoelectric ceramic, the structure is relatively simple, the production and the manufacture are convenient, and the production and the manufacture cost of the ultrasonic nerve regulation and control device are favorably reduced.
In the embodiment of the present invention, the inner cylinder diameter of the acoustic collimator 300 is tapered in a direction away from the planar ultrasonic transducer 100.
The present invention is not limited to the above preferred embodiments, and any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.