KR20230146725A - Ultrasound sensor and controlling method of the same based on silicon photonic ring resonator and cantilever structure - Google Patents

Abstract

An ultrasonic sensor according to an embodiment of the present disclosure includes a straight optical waveguide set to allow light to pass through, a first loop set to allow light to pass through, and positioned away from the optical waveguide in a direction parallel to the plane where the optical waveguide is located. loop) resonator, including a first membrane, at least a portion of which is positioned spaced apart from the first loop resonator, and an optical transmitter for incident light onto one end of the optical waveguide, wherein the first membrane has one end of the first membrane facing away from the optical waveguide. It has a cantilever structure with an axis, and the first membrane vibrates about one end of the membrane due to external sound pressure, so that the distance between at least a part of the first membrane and the first loop resonator may change.

Description

Ultrasonic sensor and control method based on silicon photonic ring resonator and cantilever structure {ULTRASOUND SENSOR AND CONTROLLING METHOD OF THE SAME BASED ON SILICON PHOTONIC RING RESONATOR AND CANTILEVER STRUCTURE}

The present disclosure relates to an ultrasonic sensor and a method of operating the same, and more specifically, to an ultrasonic sensor based on an optical microring resonator and a membrane having a cantilever structure and a method of operating the same.

Ultrasound imaging is widely used in medical imaging, and ultrasonic diagnostic imaging devices and photo-acoustic diagnostic imaging devices receive ultrasonic waves reflected or generated from the human body from an ultrasonic sensor and electrically Transform it into a signal.

Piezo-electric transducers and micro-machined ultrasound transducers (MUT) are used as elements of ultrasonic sensors.

Attempts to acquire photo-acoustic images from vascular and esophageal endoscopes are continuing, and for this purpose, miniaturization of ultrasonic sensor elements is essential. In addition, despite the miniaturization of devices, the number of devices is increasing, so the increase in wiring for receiving electrical signals from each device still poses a major problem in production and operation. For example, in the case of an ultrasonic two-dimensional probe, there may be more than 1,000 wires connected to each element.

MUT-based ultrasonic sensors have the advantage of not requiring electrical wiring or matching circuits, but due to high electrical impedance, the signal-to-noise ratio (SNR) is low and, as a result, the image bit resolution (image bit depth) is low. There is a problem with it being low.

Prior art 1 discloses ultrasonic sensor technology based on optical resonance technology. Prior Art 1 discloses an ultrasonic piezoelectric transducer based on an optical micro-ring resonator integrated into the acoustic membrane of a silicon chip.

The waveguide and ring resonator of prior art 1 are integrated on the upper surface of the membrane, and the shape of the optical resonator changes due to deflection of the membrane due to external pressure, and the resulting change in optical resonance occurs. It is based on

However, prior art 1 has the problem of high difficulty in the manufacturing process because the ring resonator must be integrated and manufactured on the upper surface of the membrane, especially the upper surface of the membrane that essentially has no support structure.

In addition, prior art 1 essentially requires changing the degree of sagging deformation of the membrane in order to increase sensitivity in response to external pressure or detailed design of sound pressure-optical conversion. There is a problem that it is difficult to control it in the direction desired by the designer.

Prior art 1: S.M. Leinders et al., "A sensitive optical micro-machined ultrasound sensor (OMUS) based on a silicon photonic ring resonator on an acoustical membrane", Scientific Reports, 5, Article number: 14328, September 2015

One embodiment of the present disclosure provides an ultrasonic sensor based on optical resonance and a method of operating the same.

Another embodiment of the present disclosure provides an ultrasonic sensor whose optical properties can be precisely and easily changed and a method of operating the same.

Another embodiment of the present disclosure provides an ultrasonic sensor whose optical properties and mechanical properties can be changed in detail and easily, and a method of operating the same.

Another embodiment of the present disclosure provides an ultrasonic sensor that can be easily manufactured using a silicon process.

An ultrasonic sensor according to an embodiment of the present disclosure includes a straight optical waveguide set to allow light to pass through, a first loop set to allow light to pass through, and positioned away from the optical waveguide in a direction parallel to the plane where the optical waveguide is located. loop) resonator, including a first membrane, at least a portion of which is positioned spaced apart from the first loop resonator, and an optical transmitter for incident light onto one end of the optical waveguide, wherein the first membrane has one end of the first membrane facing away from the optical waveguide. It has a cantilever structure with an axis, and the first membrane vibrates about one end of the membrane due to external sound pressure, so that the distance between at least a part of the first membrane and the first loop resonator may change.

An ultrasonic sensor control method according to an embodiment of the present disclosure includes steps in which at least part of each step is controlled by a processor, including the step of incident light onto one end of a straight optical waveguide set to allow light to pass through, and The membrane, which is located away from the optical waveguide in a direction parallel to the plane and away from the loop resonator set to allow light to pass through, vibrates with the end of the membrane in the direction away from the optical waveguide as its axis due to external sound pressure, and the membrane's It may include measuring a change in the intensity of light emitted from the other end of the optical waveguide due to vibration.

The ultrasonic sensor according to an embodiment of the present disclosure can improve the sensitivity of ultrasonic measurement based on optical resonance.

The ultrasonic sensor according to an embodiment of the present disclosure can easily and precisely modify optical properties or mechanical properties, and thus can be designed to be suitable for various application fields.

The ultrasonic sensor according to an embodiment of the present disclosure can be easily manufactured using a silicon process, and thus has high production reproducibility.

Figure 1 is a diagram showing an environment for driving an ultrasonic sensor according to an embodiment of the present disclosure.
Figure 2 is a perspective view of an ultrasonic sensor according to an embodiment of the present disclosure.
Figure 3 is a top plan view of an ultrasonic sensor according to an embodiment of the present disclosure.
Figure 4 is an experiment result showing the optical resonance characteristics of an ultrasonic sensor according to an embodiment of the present disclosure.
Figure 5 is a top plan view of an ultrasonic sensor according to an embodiment of the present disclosure.
Figure 6 is a side view of an ultrasonic sensor according to an embodiment of the present disclosure, as seen from the side.
Figure 7 is a top plan view of an ultrasonic sensor according to an embodiment of the present disclosure.
Figure 8 is a side view of an ultrasonic sensor according to an embodiment of the present disclosure, as seen from the side.
Figure 9 is a top plan view of an ultrasonic sensor according to other embodiments of the present disclosure.
Figure 10 is a side view of an ultrasonic sensor according to an embodiment of the present disclosure, as seen from the side.
Figure 11 is an experiment result showing sensitivity characteristics through a change in the design of a cantilever according to an embodiment of the present disclosure.
Figure 12 is an experiment result showing the bandwidth characteristics of an ultrasonic sensor according to an embodiment of the present disclosure.
Figure 13 is a plan view of the cell array structure according to an embodiment of the present disclosure as seen from the top of the ultrasonic wave.
Figure 14 is a flowchart explaining a control method of an ultrasonic sensor according to an embodiment of the present disclosure.

Hereinafter, embodiments disclosed in the present specification will be described in detail with reference to the attached drawings. However, identical or similar components will be assigned the same reference numbers regardless of reference numerals, and duplicate descriptions thereof will be omitted. The suffixes “module” and “part” for components used in the following description are given or used interchangeably only for the ease of preparing the specification, and do not have distinct meanings or roles in themselves. Additionally, in describing the embodiments disclosed in this specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed descriptions will be omitted. In addition, the attached drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the attached drawings, and all changes included in the spirit and technical scope of the present invention are not limited. , should be understood to include equivalents or substitutes.

Terms containing ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

An environment for driving an ultrasonic sensor according to an embodiment of the present disclosure will be described with reference to FIG. 1 .

The ultrasonic sensor according to an embodiment of the present disclosure may operate as the sensor array 1000 of the ultrasonic probe 200 electrically and mechanically connected to the ultrasonic imaging device 3000. The sensor array 1000 may include a plurality of cells 100, and each cell may include a ring resonator based on photonic resonance and a membrane of a cantilever structure according to the embodiments below. External ultrasonic sound pressure can be converted into an electrical signal due to its optical/mechanical properties.

The sensor array 1000 may have a plurality of optical waveguides, and a plurality of cells 100 located close to each optical waveguide may be optically connected. Each cell 100 may include a ring resonator and a membrane, which are described in detail below. The optical connection is not a physically connected structure, but means that light from the optical waveguide can propagate to an optically connected cell (for example, a ring resonator included in the cell) by optical resonance.

Among the plurality of cells 100 disposed close to and optically connected to the same optical waveguide of the sensor array 1000, at least two cells may include ring resonators having different peripheral lengths.

Among the plurality of cells 100 disposed close to and optically connected to the same optical waveguide of the sensor array 1000, at least two cells may include membranes with different areas.

Among the plurality of cells 100 disposed in close proximity to each other and optically connected to different optical waveguides of the sensor array 1000, at least two cells may include ring resonators with the same peripheral length or membranes with the same area. For example, cells located in the same order for different optical waveguides based on one end of the optical waveguide through which light enters (e.g., cells of the same color in FIG. 1) are ring resonators with the same circumference length or area. It may include such a membrane.

An ultrasonic sensor according to an embodiment of the present disclosure will be described with reference to FIG. 2 . Figure 2 shows one cell of the sensor array 1000, or the sensor may be comprised of a single cell. Figure 2 is a perspective view with some layers (eg, top layers) of an ultrasonic sensor partially removed. FIG. 3 is a schematic plan view of the ultrasonic sensor of FIG. 2 viewed along the Z-axis, which is a vertical direction, from the top of the substrate 140 where the optical waveguide 110 and the first loop resonator 120 are located.

The ultrasonic sensor includes a first waveguide 110, which is a straight optical waveguide set to allow light to pass through, and an optical waveguide 110 in a direction parallel to the plane, in a plane where the optical waveguide 110 is located, and set to allow light to pass through. It includes a first loop resonator 120 in the form of a ring positioned at a distance d1 from .

The optical waveguide 110 and the first loop resonator 120 are located on the same plane of the substrate 140, and in this specification, the plane can be understood as a plane formed by the X and Y axes, and the axis perpendicular to the plane is This is explained in terms of the Z axis. Light traveling through the optical waveguide 110 is explained as propagating along the Y-axis.

A fluid such as air or another dielectric material may exist between the optical waveguide 110 and the first loop resonator 120, and may change the material or change the electromagnetic properties of the material, or change the material between the optical waveguide 110 and the first loop resonator 120. By changing the separation distance of the loop resonator 120, the propagation characteristics of light propagating through the optical waveguide 110 can be changed. In one embodiment, the optical waveguide 110 may be formed to have a height of 220 nm on the substrate 140.

The ultrasonic sensor includes an optical transmitter 150 that transmits light to one end of the optical waveguide 110.

The ultrasonic sensor may further include an optical receiver 160 that measures light emitted from the other end of the optical waveguide 110 in a direction away from the one end, and in this case, the optical receiver 160 receives light at a preset first wavelength. A change in the intensity of light emitted from the other end of the waveguide 110 can be measured.

The ultrasonic sensor may include a first membrane 130, and at least a portion of the first membrane 130 may be positioned at a predetermined distance away from the first loop resonator 120.

Referring to FIG. 3, in one embodiment, when viewed in the Z-axis, which is a direction perpendicular to the substrate 140, at least a portion of the first membrane 130 overlaps the first loop resonator 120 and includes a first loop resonator ( It can be located away from 120).

Referring to FIG. 5 , in one embodiment, when viewed from the Z-axis in a direction perpendicular to the substrate 140, it does not overlap the first loop resonator 120, and at least a portion of the first membrane 130 is aligned with the substrate 140. ) may be positioned spaced apart from the first loop resonator 120 in a direction parallel to the plane.

The first membrane 130 may be implemented as a planar membrane having a predetermined area when viewed from the Z-axis, which is a direction perpendicular to the substrate 140. In another embodiment, a dimple or cavity may be formed in a portion of the first membrane 130. The cavity may be a penetrating structure that communicates the upper space and lower space of the planar membrane. When forming a depression or cavity, the frequency characteristics of ultrasonic waves that can be sensed can be determined through the design of the size of the depression or cavity, and mechanical properties such as damping of the cantilever against the external pressure of the first membrane 130 can also be changed. You can.

When light with a wide spectrum is transmitted through the optical waveguide 110, part of the optical spectrum is combined into the first loop resonator 120 adjacent to the optical waveguide 110 and measured at the other end of the optical waveguide 110. The spectrum of the light has a specific wavelength ( ), a phenomenon in which the intensity of light is reduced can be seen.

Assuming that there is no first membrane 130, a specific wavelength ( ) and the circumferential length (l) of the first loop resonator 120 have the same relationship as <Equation 1>.

m is an integer, is the effective index of refraction of the first loop resonator 120.

By positioning the first membrane 130 at an appropriate distance from the first loop resonator 120, the first membrane 130 has the same effect as partially increasing the circumferential length (l) of the first loop resonator 120. , and the specific wavelength at which the light intensity decreases compared to when the first membrane 130 is not present may be different.

In this case, the circumferential length (l) of the first loop resonator 120 increases due to the first membrane 130 located close to the first loop resonator 120, and as a result, the optical waveguide 110 The wavelength at which the light intensity decreases is the resonance wavelength ( ) can be said. Resonant wavelength ( ) changes according to the change in the separation distance between the first membrane 130 and the first loop resonator 120.

Referring to FIG. 3, when light with a wide spectrum is transmitted through the optical waveguide 110, a portion of the optical spectrum, such as the resonance wavelength, is transmitted to the first loop resonator 120 adjacent to the optical waveguide 110. As the light propagates and is measured at the other end of the optical waveguide 110, the light intensity of the wavelength corresponding to the resonance wavelength is lowered. However, the first membrane 130 is positioned so far apart that light incident on one end of the optical waveguide 110 does not propagate directly to the first membrane 130. However, the first membrane 130 is located close to and spaced apart from the first loop resonator 120, thereby changing the effective peripheral length of the first loop resonator 120, thereby affecting the light propagation characteristics of the optical waveguide 110. It's crazy.

The first membrane 130 has a cantilever structure capable of vibrating in a plane structure with one end facing away from the optical waveguide 110 as its axis. At least a portion 142 of the substrate 140 may have a depression in which at least a portion of the substrate 140 is depressed in the Z-axis direction, or may include a cavity that is a penetrating structure that communicates the upper space and the lower space of the substrate 140. there is. The first membrane 130 has a cantilever structure and vibrates up and down with one end in the Z-axis direction in the depression or cavity of the substrate due to external negative pressure, and the vibration of the first membrane 130 causes the first membrane 130 to vibrate. The separation distance from the loop resonator 120 may vary.

In this specification, the cantilever structure has one end connected and fixed to the substrate 140 and the other end is not fixed, and does not only mean the shape of a beam, but when viewed from the Z axis perpendicular to the substrate 140. A structure having a predetermined area includes one end fixed to the substrate 140.

Referring to FIG. 4, the resonance wavelength due to the first membrane 130 and the first loop resonator 120 ( ) changes according to the change in the separation distance between the first loop resonators 120 due to the vibration of the first membrane 130. The external sound pressure caused by the incident ultrasonic waves on the sensor initially causes at least a portion of the first membrane 130 to approach the first loop resonator 120 with one end as the axis. Accordingly, the circumferential length of the first loop resonator 120 becomes longer, and the resonance wavelength ( ) moves like the dotted line in Figure 4. In Figure 4, when the first membrane 130 is positioned at regular intervals (de-coupled) in the upper direction of the first loop resonator 120, the resonance wavelength ( ) was 1550 nm, but when it became close (coupled) to the first loop resonator 120 for a moment due to the external pressure of ultrasonic waves, the resonance wavelength ( ) can be confirmed to have moved to 1551.5nm. Therefore, a preset measurement wavelength ( ), when measuring the change in light intensity, as shown in FIG. 4, the first membrane 130 approaches the first loop resonator 120, thereby increasing the measurement wavelength ( ), the intensity of light increases. Measurement wavelength ( ), the change in intensity of light is due to the external pressure (acoustic pressure) of ultrasonic waves, so an ultrasonic sensor can be implemented by recognizing this as the size of ultrasonic waves and generating an electrical signal based on the change in intensity of light.

An example of an ultrasonic sensor will be described with reference to FIGS. 5 and 6 . Detailed descriptions of parts that overlap with those explained previously will be omitted.

Referring to FIG. 5, in one embodiment, when viewed from the Z-axis in a direction perpendicular to the substrate 140a, it does not overlap the first loop resonator 120a, and at least a portion of the first membrane 130a is aligned with the substrate 140a. ) may be positioned spaced apart from the first loop resonator 120a in a direction parallel to the plane, and a side view viewed from the Y axis along the cutting plane A-A' may be as shown in FIG. 6.

The first membrane 130a may include a phase shifter 136a having a predetermined thickness when viewed from the Y axis, and a cantilever 134a connecting the phase shifter 136a and an axis fixed to the substrate. . In one embodiment, the thickness h of the cantilever 134a may be thinner than the thickness of the phase shifter 136a, and at least a portion of the cantilever 134a may be formed at a lower height than the upper surface of the first loop resonator 120a. You can.

At least a portion 142a of the substrate 140a has a depression or cavity, and the first membrane 130a vibrates up and down in the depression or cavity due to the external pressure of ultrasonic waves, thereby increasing the separation distance from the first loop resonator 120a. (d3) can change. The phase shifter 136a of the first membrane 130a moves downward due to the external pressure of ultrasonic waves in the neutral position A1 and then moves to the upper position A2 due to the elasticity of the cantilever 134a. can do. Resonant wavelength ( ), unlike FIG. 4, can move to a lower wavelength range because the distance between the first membrane 130a and the first loop resonator 120a increases due to the external pressure of ultrasonic waves.

In one embodiment, the cantilever 134a and the phase shifter 136a of the first membrane 130a may each have a predetermined area when viewed in a direction perpendicular to the substrate 140a. When viewed in a direction perpendicular to the substrate 140a, the phase shifter 136a may have a first surface and the cantilever 134a may have a second surface.

The first surface of the phase shifter 136a and the second surface of the cantilever 134a may have different geometrical shapes. For example, a cavity may not be formed on the first side of the phase shifter 136a, and a dimple structure may be formed on the cantilever 134a. Alternatively, the cantilever 134a may include a plurality of penetrating structures 132a that communicate with the upper space and lower space of the cantilever 134a.

The movement of the cantilever 134a due to the external pressure of ultrasonic waves can be controlled through experiments and detailed design of the penetrating structure 132a and the recessed structure of the cantilever 134a. In addition, the frequency characteristics of ultrasonic waves that can be sensed can be determined according to the vibration characteristics based on the design structure of the penetrating structure 132a and the recessed structure of the cantilever 134a. For example, the fewer penetrating structures 132a, the narrower the sensing ultrasonic frequency band can be sensed, and the more penetrating structures 132a, the less vibration resistance to surrounding air or fluid, allowing sensing of a wider band of ultrasonic frequencies. can do.

The cantilever 134a and the phase shifter 136a may be implemented with materials having different characteristics. For example, optical loss, refractive index, elasticity, optical dispersion, viscosity, or density may be made of different materials. .

Another example of an ultrasonic sensor will be described with reference to FIGS. 7 and 8 . Detailed descriptions of parts that overlap with those explained previously will be omitted.

The first membrane 130b overlaps at least a portion of the first loop resonator 120b when viewed in the Z-axis, which is a direction perpendicular to the substrate 140b, and at least a portion of the first membrane 130b is visible from the substrate 140b. It may be positioned at a predetermined distance d2 from the first loop resonator 120b in the vertical direction, and a side view viewed from the Y-axis along the cutting plane A-A' may be as shown in FIG. 8.

Referring to FIG. 8, the first membrane 130b may include a phase shifter 136b having a predetermined thickness when viewed from the Y axis, and a cantilever 134b connecting the phase shifter 136b and an axis fixed to the substrate. You can. In one embodiment, at least a portion of the cantilever 134a is formed at a height lower than the upper surface of the first loop resonator 120a, and at least a portion of the phase shifter 136 is positioned higher than the upper surface of the first loop resonator 120a. can be formed in At least a portion of the phase shifter 136b may be spaced apart by a predetermined distance d3 along the Y-axis parallel to the substrate 140b.

At least a portion 142b of the substrate 140b has a depression or cavity, and the first membrane 130b vibrates up and down in the depression or cavity due to the external pressure of ultrasonic waves, thereby increasing the separation distance from the first loop resonator 120b. (d2 and d3) can vary. The phase shifter 136b of the first membrane 130b moved from the neutral position A1 in a downward direction where the separation distance d2 between the upper surfaces of the first loop resonator 120b became closer due to the external pressure of ultrasonic waves. Due to the elasticity of the cantilever 134b, it can perform a oscillating movement moving to the upper position A2. Those skilled in the art can understand that the position A2 of the first membrane 130b due to the elasticity of the cantilever 134b in FIG. 8 is exaggerated for explanation. Resonant wavelength ( ) may be the same as Figure 4.

The cantilever 134b of the first membrane 130b may include a structure 132b that penetrates and connects the upper space and the lower space. As explained with reference to FIGS. 5 and 6, the movement of the cantilever 134b due to the external pressure of ultrasonic waves can be controlled through experiments and detailed design of the penetration structure 132b and the recessed structure of the cantilever 134b. , the frequency characteristics of ultrasonic waves that can be sensed can be determined.

Other embodiments of the phase shifter 136b of the first membrane 130b will be described with reference to FIGS. 8 and 9.

One end of the first membrane 130b is fixed to the substrate 140b and acts as an axis of vibration movement, and the phase shifter 136b located at the other end in the opposite direction is spaced apart from the upper surface of the first loop resonator 120b. It may be in a form that follows at least a portion of the circumference of the first loop resonator 120b while maintaining the distance d2. When viewed from the Z-axis, which is the vertical direction of the substrate 140b, a portion of the phase shifter 136b1 follows the circumference of the first loop resonator 120b, as shown in FIG. 9 (a), or as shown in FIG. 9 (b). Likewise, the entire phase shifter 136b2 may have a shape that follows the circumference of the first loop resonator 120b. When the phase shifter 136b has the shape shown in FIG. 9 (b), the effect of increasing the circumferential length of the first loop resonator 120b is further increased, so the resonance wavelength ( ) and the measurement wavelength ( ), the change in light intensity may be greater. Therefore, sensitivity to ultrasound may increase.

In one embodiment, the phase shifters 136b1 and 136b2 may include recessed structures or penetrating structures, and the size or number of recessed structures or penetrating structures may be determined by the recessed structures or penetrating structures of the cantilevers 134b1 and 134b2. The size or number of structures may be different. The optical and/or mechanical effects of the phase shifters 136b1 and 136b2 may increase due to the photonic crystal effect depending on the design of the recessed or perforated structure.

Another example of an ultrasonic sensor will be described with reference to FIG. 10 . Detailed descriptions of parts that overlap with those explained previously will be omitted.

In one embodiment, the first membrane overlaps at least a portion of the first loop resonator 120c when viewed from the Z-axis, which is a direction perpendicular to the substrate, and at least a portion of the first membrane overlaps the first loop resonator 120c in a direction perpendicular to the substrate. It may be positioned at a predetermined distance (d2) apart from (120c), and may be positioned at a predetermined distance (d3, d4) away from the first loop resonator (120c) in a direction parallel to the substrate. That is, the phase shifter 136c of the first membrane may be positioned to be spaced apart from the three surfaces of the first loop resonator 120c at a predetermined distance (d2, d3, d4). Therefore, the effect of increasing the circumferential length of the first loop resonator 120c is further increased, so the resonance wavelength ( ) and the measurement wavelength ( ), the change in light intensity may be greater. Therefore, sensitivity to ultrasound may increase.

With reference to FIG. 10, the results of a sensitivity test according to the cantilever design structure of the ultrasonic sensor will be described.

As explained previously, through experiments and detailed design of the cantilever's penetrating structure and recessed structure, not only can the movement of the cantilever due to the external pressure of ultrasonic waves be controlled, but also the ultrasonic sensing can be controlled according to the thickness (t) and length (l) of the cantilever. Sensitivity can be controlled.

The center frequency of the sensing ultrasound ( ) has the same relationship as <Equation 2>, and ultrasonic sensitivity (S) has the same relationship as <Equation 3>. It can be confirmed from the experimental results of FIG. 11 that the thickness (t) of the cantilever is By appropriately designing the length (l), the sensitivity of ultrasonic sensing to the ultrasonic center frequency according to the inspection area can be controlled.

The results of the measurement frequency band bandwidth experiment of the ultrasonic sensor will be described with reference to FIG. 12.

The optical waveguide, loop resonator, and membrane (phase shifter, cantilever) of the ultrasonic sensor according to the embodiments of the present specification may be implemented on a substrate through semiconductor processes such as deposition and etching. Therefore, it is possible to manufacture a cell array structure containing a large number of cells in a very narrow area, and has excellent production reproducibility.

Referring to FIG. 15, in one embodiment, the ultrasonic sensor includes a waveguide 1510 formed on the upper surface of the optical substrate 1540, a loop resonator 1520 located close to the waveguide 1510, and a direction perpendicular to the substrate 1540. When viewed from the Z-axis, at least a portion of the membrane may overlap the loop resonator 1520 and be positioned spaced apart from the loop resonator 1520 . The membrane may have a cantilever 1534 structure that vibrates up and down due to ultrasonic sound pressure. The ultrasonic sensor may include a dissipative layer 1550 made of an elastic material such as polydimethylsiloxane (PDMS) on the upper surface of the cantilever 1534. By adding the diffusion layer 1550, the bandwidth can be dramatically improved compared to the conventional PZT-based ultrasonic probe, as shown in the experimental results of FIG. 12. When an elastic diffusion layer 1550 is added to the upper surface of the cantilever 1534, the mechanical attenuation characteristics of the cantilever 1534 vibration caused by ultrasonic external pressure can be modified due to the acoustic impedance of the diffusion layer, and the mechanical attenuation of the cantilever 1534 vibration is The effect of increasing the bandwidth of the frequency domain can be obtained. The diffusion layer 1550 is formed by applying PDMS, etc. to the upper surface of the layer where the cantilever 1534 is formed, curing it, and etching the cantilever 1534 and the diffusion layer 1550. can be formed simultaneously. The diffusion layer 1550 may be formed in a similar manner in the embodiments previously described with reference to other drawings.

An ultrasonic sensor with a cell array structure will be described with reference to FIG. 13.

The ultrasonic sensor may include a plurality of optical waveguides, and one of the optical waveguides 1310 may be optically connected to a plurality of cells. Among the plurality of cells optically connected to the same optical waveguide, at least two cells (1320, 1330) each have ring resonators (1322, 1332) with different circumferential lengths and membranes with different areas when viewed in a direction perpendicular to the substrate. May include (1324, 1334).

Since each cell includes ring resonators 1322 and 1332 with different circumference lengths, the resonant wavelength ( , ) may be different.

The ultrasonic sensor may further include an optical receiver that measures light emitted from the other end of the optical waveguide 1310. In this case, the optical receiver measures the change in intensity of light emitted from the other end of the optical waveguide 1310 in a different manner for each cell. Measurement wavelength ( , ) can be measured. Therefore, the level of ultrasonic sound pressure can be measured separately for each cell.

5 and 6, wherein at least a portion of the membrane 1324, 1334 does not cover a portion of each ring resonator 1322, 1332 when viewed in the Z-axis perpendicular to the plane of the substrate. It may be implemented in a form like , or it can be implemented in a form like FIGS. 7 and 8 that covers part of each ring resonator (1322, 1332).

The membranes 1324 and 1334 may include a phase shifter positioned in close proximity to the ring resonators 1322 and 1332, and a cantilever connecting the phase shifter and an axis fixed to the substrate. As described above, at least a portion of the phase shifter and/or cantilever may be formed with a depression or a cavity, which is a penetrating structure that communicates the upper space and the lower space. When a penetrating structure is formed in the phase shifter and the cantilever, the geometry of the penetrating structure may be different. For example, at least one of the diameter of the penetrating structure or the number of penetrating structures may be different.

The control method of the ultrasonic sensor will be described with reference to FIG. 14.

The ultrasonic sensor may be one that transmits a control signal from the processor of the ultrasonic body 3000 as shown in FIG. 1 to the ultrasonic probe 2000. Alternatively, the ultrasonic probe 2000, which has received a control signal from the processor, may control the ultrasonic sensor array 1000, the optical transmitter, and the optical receiver to match the received control signal.

The processor injects light with a plurality of spectra into one end of the linear optical waveguide (S110). Afterwards, a portion of the optical spectrum incident on the optical waveguide may propagate to a loop resonator located away from the optical waveguide in the plane where the optical waveguide is located. The wavelength of light propagating to the loop resonator may be based on the circumferential length of the loop resonator and may follow Equation 1. The separation distance from the loop resonator may change as the membrane, which is located close to the loop resonator and affects the effective circumferential length of the loop resonator, vibrates (moves up and down) around one end fixed to the substrate by the sound pressure of ultrasonic waves. . The membrane is positioned far away from the optical waveguide so that light incident on one end of the optical waveguide does not propagate directly.

The processor may measure the intensity at a specific wavelength of light emitted from the other end of the optical waveguide (S120) and generate an output by relating the change in intensity to the level of ultrasonic sound pressure.

The processor measures changes in the intensity of light at different wavelengths to determine the magnitude of ultrasonic sound pressure in at least two different cells among the plurality of cells included in the ultrasonic sensor array 1000, and changes the intensity of light measured at different wavelengths. Based on the intensity change, the level of ultrasonic sound pressure can be determined for each cell.

The present disclosure described above can be implemented as computer-readable code on a program-recorded medium. Computer-readable media includes all types of recording devices that store data that can be read by a computer system. Examples of computer-readable media include HDD (Hard Disk Drive), SSD (Solid State Disk), SDD (Silicon Disk Drive), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. There is. Additionally, the computer may include a processor for each device.

Meanwhile, the program may be specially designed and configured for the present disclosure, or may be known and usable by those skilled in the art of computer software. Examples of programs may include not only machine language code such as that created by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

In the specification (particularly in the claims) of the present disclosure, the use of the term “above” and similar referential terms may refer to both the singular and the plural. In addition, when a range is described in the present disclosure, the invention includes the application of individual values within the range (unless there is a statement to the contrary), and each individual value constituting the range is described in the detailed description of the invention. It's the same.

Unless there is an explicit order or description to the contrary regarding the steps constituting the method according to the present disclosure, the steps may be performed in any suitable order. The present disclosure is not necessarily limited by the order of description of the steps above. The use of any examples or illustrative terms (e.g., etc.) in the present disclosure is merely to describe the present disclosure in detail, and unless limited by the claims, the scope of the present disclosure is limited by the examples or illustrative terms. It doesn't work. In addition, those skilled in the art will recognize that various modifications, combinations and changes may be made according to design conditions and factors within the scope of the appended claims or their equivalents.

Therefore, the spirit of the present disclosure should not be limited to the above-described embodiments, and the scope of the patent claims described below as well as all scopes equivalent to or equivalently changed from the claims are within the scope of the spirit of the present disclosure. It will be said to belong to

100: cell
110, 110a, 110b: optical waveguide
120, 120a, 120b: loop resonator
130, 130a, 130b: Membrane
132, 132a, 132b: Penetrating structure
140, 140a, 140b: substrate
142, 142a, 142b: depression or cavity
150: Optical transmitter
160: Optical receiver
1000: sensor array
2000: Ultrasound probe
3000: Ultrasonic body

Claims (20)

A straight optical waveguide configured to allow light to pass through;
a first loop resonator configured to allow light to pass through and positioned away from the optical waveguide in a direction parallel to a plane where the optical waveguide is located;
a first membrane, at least a portion of which is positioned spaced apart from the first loop resonator; and
It includes an optical transmitter that makes light incident on one end of the optical waveguide,
The first membrane has a cantilever structure with one end of the first membrane as its axis in the direction away from the optical waveguide, and the first membrane vibrates about one end of the first membrane due to external sound pressure, causing at least one end of the first membrane to vibrate. In some cases, the separation distance from the first loop resonator changes,
Ultrasonic sensor.
According to claim 1,
A portion of the spectrum of light incident on one end of the optical waveguide propagates to the first loop resonator,
The first membrane is positioned spaced apart from the optical waveguide to prevent light incident to one end of the optical waveguide from propagating.
Ultrasonic sensor.
According to claim 1,
The other end of the first membrane in the opposite direction to the one end has a shape that follows at least a portion of the circumference of the first loop resonator with a predetermined separation distance,
Ultrasonic sensor.
According to claim 1,
At least a portion of the first membrane is positioned spaced apart from the first loop resonator in a direction perpendicular to the plane,
When viewed in a direction perpendicular to the plane, at least a portion of the first membrane overlaps with at least a portion of the first loop resonator,
The first membrane has a separation distance between the first loop resonator and the plane perpendicular to the plane according to vibration centered on one end of the first membrane.
Ultrasonic sensor.
According to clause 4,
The first membrane is,
a phase shifter positioned spaced apart from the first loop resonator in a direction perpendicular to the plane; and
At least a portion of the cantilever includes the cantilever formed at a lower height than the upper surface of the first loop resonator,
Ultrasonic sensor.
According to clause 5,
The phase shifter and the cantilever have different thicknesses in a direction perpendicular to the plane,
Ultrasonic sensor.
According to clause 5,
The phase shifter and the cantilever are made of materials that have different optical loss, refractive index, elasticity, optical dispersion, viscosity, or density. felled,
Ultrasonic sensor.
According to clause 5,
The phase shifter and the cantilever each have a first surface and a second surface having a predetermined area when viewed in a direction perpendicular to the plane,
The first side of the phase shifter and the second side of the cantilever have different geometrical shapes,
Ultrasonic sensor.
According to clause 5,
The cantilever has a predetermined area when viewed in a direction perpendicular to the plane, and includes a plurality of penetrating structures that communicate the upper space and lower space of the cantilever with respect to the plane,
Ultrasonic sensor.
According to claim 1,
At least a portion of the plane includes a recessed depression or a cavity, which is a penetrating structure that communicates the upper space and the lower space of the plane,
The first membrane is set to vibrate around one end of the first membrane as an axis by external negative pressure in the depression or the cavity,
Ultrasonic sensor.
According to claim 1,
a second loop resonator configured to allow light to pass through and positioned spaced apart from the optical waveguide and the first loop resonator in a direction parallel to the plane where the optical waveguide is located; and
Further comprising a second membrane, at least a portion of which is positioned spaced apart from the second loop resonator,
The second membrane has a cantilever structure with one end of the second membrane as its axis in the direction away from the optical waveguide, and the second membrane vibrates about one end of the second membrane due to external sound pressure, causing at least one end of the second membrane to vibrate. In some cases, the separation distance from the first loop resonator changes,
Ultrasonic sensor.
According to claim 11,
The circumferential length of the second loop resonator is different from the circumferential length of the first loop resonator,
Ultrasonic sensor.
According to claim 11,
It further includes an optical receiver that measures a change in the intensity of light emitted from the other end of the optical waveguide at a preset first wavelength and a second wavelength,
The first wavelength and the second wavelength are different from each other,
Ultrasonic sensor.
According to claim 11,
When viewed in a direction perpendicular to the plane, a first portion where the first membrane overlaps the first loop resonator and a second portion where the second membrane overlaps the second loop resonator are, with respect to the plane, Comprising a plurality of penetrating structures communicating the upper space and lower space of the first membrane and the second membrane,
Ultrasonic sensor.
According to claim 14,
The penetrating structures of the first part and the second part have different geometric structures,
Ultrasonic sensor.
According to claim 15,
The penetrating structures of the first part and the second part are different from each other in either the diameter of the penetrating structure or the number of penetrating structures,
Ultrasonic sensor.
According to claim 1,
The first loop resonator includes at least three surfaces that are not in contact with the plane,
Due to external sound pressure, the first membrane vibrates while the separation distance from at least two surfaces of the first loop resonator that are not in contact with the plane changes.
Ultrasonic sensor.
Steps in which at least a portion of each step is controlled by a processor,
Injecting light into one end of a straight optical waveguide configured to allow light to pass through; and
The membrane is located away from the optical waveguide in a direction parallel to the plane where the optical waveguide is located and away from a loop resonator set to allow light to pass through. The membrane is located in a direction away from the optical waveguide due to external sound pressure. Vibrating one end of the membrane as an axis, and measuring a change in the intensity of the light emitted from the other end of the optical waveguide due to the vibration of the membrane,
Control method of ultrasonic sensor.
According to clause 18,
The loop resonator and the membrane corresponding to each other constitute one cell, and the cells are plural,
Control method of ultrasonic sensor.
According to clause 19,
The step of measuring the change in intensity of light is,
measuring changes in light intensity at different wavelengths; and
A step of determining the level of the sound pressure for each cell based on changes in the intensity of light measured at different wavelengths,
Different wavelengths are set to be associated with different cells,
Control method of ultrasonic sensor.

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