Ultrasonic transducers receive acoustic energy at ultrasonic frequencies as an input and provide electrical energy as an output, or receive electrical energy as an input and provide acoustic energy at ultrasonic frequencies as an output. A structure may be coupled to the ultrasonic transducer to receive or transmit ultrasonic waves. An ultrasonic transducer can include a piece of piezoelectric material that changes size in response to the application of an electric field. If the electric field is made to change at a rate comparable to ultrasonic frequencies, then the piezoelectric element can vibrate and generate acoustic pressure waves at ultrasonic frequencies. Likewise, when the piezoelectric element resonates in response to impinging ultrasonic energy, the element can generate electrical energy.
Implementations of the disclosed subject matter provide an apparatus that includes a conical structure having a first circumference and a second circumference, respectively located at opposite ends of the conical structure, where the first circumference has a greater length than the second circumference. A rim may be coupled at or adjacent to the first circumference of the conical structure. An ultrasonic transducer may be coupled to the second circumference of the conical structure.
Implementations of the disclose subject matter may provide an apparatus including a conical structure having a first circumference and a second circumference, respectively located at opposite ends of the conical structure, where the first circumference has a greater length than the second circumference. An angle between a plane including the second circumference and a surface of the conical structure may be 165° or greater. The apparatus may include an ultrasonic transducer coupled to the second circumference of the conical structure.
Additional features, advantages, and embodiments of the disclosed subject matter may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary and the following detailed description are examples and are intended to provide further explanation without limiting the scope of the claims.
The accompanying drawings, which are included to provide a further understanding of the disclosed subject matter, are incorporated in and constitute a part of this specification. The drawings also illustrate embodiments of the disclosed subject matter and together with the detailed description serve to explain the principles of embodiments of the disclosed subject matter. No attempt is made to show structural details in more detail than may be necessary for a fundamental understanding of the disclosed subject matter and various ways in which it may be practiced.
Implementations of the disclosed subject matter provide a conical structure coupled to an ultrasonic transducer that has a lower profile and larger opening angle than typical structures that may be coupled to a transducer. The conical structure of the disclosed subject matter may increase the rigidity of the conical structure, and may have a mass below a predetermined amount to decrease eigen-modes. In some implementations, a rim may be added to the conical structure, as well as structural ribs, to increase rigidity. Cutouts may be added to the conical structure to reduce the mass of the conical structure. The shape of the conical structure may be selected to provide acoustic matching between the operating medium (e.g., air) and a transducer.
Implementations of the disclosed subject matter provide a conical structure and a transducer to increase and/or maximize the acoustic pressure of a transmitted signal or signal-to-noise ratio of a received ultrasonic signal, so that an electric signal with decreased noise may be obtained by a receiving device for processing. That is, implementations of the disclosed subject matter provide the conical structure and transducer to generate maximum power from input signals. The conical structure and the transducer may generate a useable signal (even from received low-amplitude signals), regardless of the signal-to-noise ratio of the received signal. In the apparatus of the disclosed subject matter, the surface area of the exposed conical structure may be maximized to capture as much of an incident ultrasonic wave as possible, while having a surface area and/or size of the conical structure be below a predetermined threshold. The surface area of the conical structure may be adjusted by varying the angle between the first and second circumferences of the conical structure, as well as the height and/or the width of a rim attached to the conical structure. In some implementations, the surface area of the conical structure may be adjusted by adding a rim to a portion of the conical structure. These features of the conical structure may be adjusted so as to maximize the surface area to capture as much of an incident ultrasonic wave as possible and generate a useable signal. The thickness of the conical structure can be adjusted based on the selected material of the conical structure to tune the conical structure's stiffness and/or rigidity, so as to improve the acoustic output power for a transmitted signal or signal-to-noise ratio for a received signal. The weight of the conical structure may be adjusted (e.g., based on the selection of materials) so as to minimize a damping effect by the conical structure on the transducer, which may interfere with generating a useable signal.
In some implementations, at least one of the circumferences that defines an opening of the conical structure may be adjusted from a circle shape to an oval shape so as to adjust the focus of the conical structure for a transmitted signal or a received ultrasonic signal. The sidewalls disposed between the circumferences that define the openings of the conical structure may be formed in a planar shape, a convex shape, or a concave shape to adjust the focus of the conical structure for a transmitted signal or a received ultrasonic signal.
The first circumference 120 and the second circumference 130 may be any suitable length. In some implementations, the first circumference of the conical structure 110 may have a length that is 5-10 mm, 10-15 mm, 15-20 mm, 20-25 mm, or 25-30 mm. In some implementations, the first circumference of the conical structure 110 may have a length that is 15-25 mm. The second circumference of the conical structure 110 may have length that is 1-2 mm, 2-3 mm, 3-4 mm, or 4-5 mm. In some implementations, the second circumference of the conical structure 110 may have length that is 2-4 mm.
In some implementations, the first circumference 120 and the second circumference 130 may each form openings respectively located at opposite ends of the conical structure 110. The first circumference 120 may form a first opening 131 (e.g., as shown in
The rim 140 of the conical structure 110 shown in
The thickness 111 of the conical structure 110 may be 10-30 μm, 30-50 μm, 50-70 μm, 70-90 μm, 90-110 μm, 110-130 μm, 130-150 μm, 150-170 μm, 170-190 μm, or 190-210 μm, or any other suitable thickness. In some implementations, the thickness 111 of the conical structure 110 may be 25-105 μm. The thickness 111 may be substantially the same as the height 141 of the rim 140. In some implementations, the thickness of the conical structure 110 may be 90 μm.
A distance 180 may be any suitable distance between the first circumference 120 and the second circumference 130. The distance 180 may be 0.1-0.3 mm, 0.3-0.7 mm, 0.7-1.1 mm, or 1.1-1.5 mm. In some implementations, the distance 180 may be any suitable distance between the first circumference 120 and the second circumference 130 may be 0.7-1.2 mm.
The first circumference 120 may have a greater length than the second circumference 130. An angle 190 between the second circumference 130 and the first circumference 120 may be between a plane including the second circumference and a surface of the conical structure (e.g., as shown in
In some implementations, the angle 190 between the second circumference 130 and the first circumference 120 may be 160° or greater, and the distance 180 between the first circumference 120 and the second circumference 130 may be less than 0.9 mm. In combination with the wider angle 180, implementations where the distance 180 is less than 0.9 may form a conical structure 110 that may maximize the surface area of the conical structure 110 to capture as much of an incident ultrasonic wave as possible and generate a useable signal.
The conical structure 110 may either include or omit the rim 140. The distance 180 between the first circumference 120 and the second circumference 130 may be adjusted, as well as the angle 190 to improve the performance of the conical structure 110 of the apparatus 100. In some implementations, the distance 180 may be 0.9 mm, the angle 190 may be 160°, and the conical structure 110 may include the rim 140. This may improve the signal gain for the apparatus 100 by about 1.7 times, in comparison to a conical structure 110 with similar features that does not have a rim 140 (hereinafter referred to as a reference structure). In some implementations, the distance 180 may be 0.7 mm, the angle 190 may be 165°, and the conical structure 110 may omit the rim 140. This may improve the signal gain for the apparatus 100 by about 2.4 times in comparison to the reference structure. In some implementations, the distance 180 may be 0.7 mm, the angle 190 may be 165°, and the conical structure 110 may include the rim 140. This may improve the signal gain for the apparatus 100 by about 2.9 times in comparison to the reference structure.
The second circumference 130 of the conical structure 110 may be coupled an ultrasonic transducer 150, which may include an elongated polygon transducer membrane 160 and elongated polygon-shaped electrically active material layer 170, as shown in
The ultrasonic transducer 150 may be coupled to the conical structure 110 by applying an adhesive, bonding, welding, or soldering, and/or may be coupled in any other suitable manner. The type of coupling used may be selected based on, for example, the type of material used to form the conical structure 110. The elongated polygon-shaped electrically active material layer 170 may be disposed on the elongated polygon-shaped transducer elastic layer 160 to transform electrical excitation into a high-frequency vibration to produce ultrasonic acoustic emissions or transform received high-frequency acoustic vibration into electrical signals.
The ultrasonic transducer 150, as shown in
The ultrasonic transducer 150 may include an electromechanically active device, such as the elongated polygon-shaped electrically active material layer 170. The elongated polygon-shaped electrically active material layer 170 may be a cantilever or flexure, and may be, for example, a piezoceramic unimorph, bimorph, or trimorph. The elongated polygon-shaped electrically active material layer 170 may include an electrically active material, such as piezoelectric material or piezo-ceramic, electrostrictive material, or ferroelectric material, which may able to transform electrical excitation into a high-frequency vibration to produce ultrasonic acoustic emissions. The geometry of an elongated polygon-shaped electrically active material layer 170 may affect the frequency, velocity, force, displacement, capacitance, bandwidth, and efficiency of electromechanical energy conversion produced by the electromechanically active device when driven to output ultrasound and the voltage and current generated by the elongated polygon-shaped electrically active material layer 170 and efficiency of electromechanical energy conversion when driven by received ultrasound. The elongated polygon-shaped electrically active material layer 170 may have a hexagonal profile, or may have a profile based on any other suitable geometry. The geometry of the elongated polygon-shaped electrically active material layer 170 may be selected, for example, to tune the balance and other various characteristics of the elongated polygon-shaped electrically active material layer 170. The elongated polygon-shaped electrically active material layer 170 may be made using single layer of piezoelectric material laminated onto a single passive substrate material. The elongated polygon-shaped electrically active material layer 170 may also be made with a single piezoelectric layer and multiple passive layers; two piezoelectric layers operating anti-phase, or two piezoelectric layers, operating anti-phase and combined with one or more electrically passive materials. Different layers of the elongated polygon-shaped electrically active material layer 170 may have different shapes. For example, in a unimorph, a piezoelectric material may be shaped differently from a passive substrate material to which the piezoelectric material is bonded. The piezoelectric material, for example, piezoceramic, used in the electromechanically active device may be poled in any suitable manner, with polarization in any suitable direction.
In some implementations, the polarization direction may be along the thickness of the piezoelectric material (e.g., elongated polygon-shaped electrically active material layer 170). The polarization defines the direction along which the electric field is created in the piezoelectric material once a voltage is applied. The operation mode of the piezoelectric material may be based on how the piezoelectric material is integrated into and/or clamped to a structure. The piezoelectric material may be polarized in the direction of its thickness. As one of the surfaces of the piezoelectric material is polarized along its thickness, and because on one side of the piezoelectric material is attached to the elongated polygon transducer membrane 160, by applying the voltage across the top and bottom side of the piezoelectric material, it deforms and bends up and down (e.g., from a concave shape to a convex shape, and vice-versa).
The elongated polygon-shaped electrically active material layer 170 may be any suitable size for use in the ultrasonic transducer 150, and for vibrating at ultrasonic frequencies. The elongated polygon-shaped electrically active material layer 170 may be made in any suitable manner, such as, for example, by cutting polygon-shaped geometries from a larger laminate material. The laminate material may be made from, for example, an electrically active material, such a piezoceramic, bonded to an electrically inactive substrate, such as, for example, metals such as aluminum, Invar, Kovar, silicon/aluminum alloys, stainless steel, and brass, using any suitable bonding techniques and materials. The materials used may be non-optimal for the performance of an individual electromechanically active device. For example, materials may be selected for consistent performance across a larger number of electromechanically active device or for ease of manufacture.
The elongated polygon-shaped electrically active material layer 170 may be oriented at any suitable angle. The top surface of the elongated polygon-shaped electrically active material layer 170, which may be, for example, a passive material of a unimorph or an active material of a bimorph. The elongated polygon-shaped electrically active material layer 170 may be attached to the elongated polygon transducer membrane 160 of an ultrasonic transducer 150 in any suitable manner. For example, any sides of the elongated polygon-shaped electrically active material layer 170 may be bonded to the elongated polygon transducer membrane 160. The bonds used to secure the elongated polygon-shaped electrically active material layer 170 to the elongated polygon transducer membrane 160 may be any suitable combination of organic or inorganic bonds, using any suitable conductive and non-conductive bonding materials, such as, for example, epoxies or solders. The area of contact between the elongated polygon-shaped electrically active material layer 170 and the elongated polygon transducer membrane 160 may be any suitable size and shape. In some implementations, an ultrasonic transducer 150 may include more than one elongated polygon-shaped electrically active material layer 170. As shown in
The elongated polygon-shaped electrically active material layer 170 may be bonded in a suitable position, with the passive or active layers of the elongated polygon-shaped electrically active material layer 170 facing down depending on whether the electromechanically active device is a unimorph, bimorph, trimorph, or has some other structure. The bond may use any suitable bonding agent, solder, or epoxy. For example, conductive adhesive film may be applied to the areas of the electromechanically active device to be bonded to the elongated polygon transducer membrane 160.
The elongated polygon transducer membrane 160 may be bonded to the ultrasonic transducer 150 to create an ultrasonic device with a membrane. The elongated polygon transducer membrane 160 may be attached with adhesive in a manner that may define the outline of a number of cells of the electromechanical transducer array which the elongated polygon transducer membrane 160 will cover. The elongated polygon-shaped electrically active material layer 170 may be bonded to the elongated polygon transducer membrane 160, for example, at or near the tip of the electromechanically active device. The elongated polygon transducer membrane 160 may be multiple separate pieces of material. The elongated polygon transducer membrane 160 may act to acoustically couple the motion of cantilevers to the air, as the motion of cantilevers may cause the membrane to move.
The elongated polygon transducer membrane 160 may be any suitable material or composite material structure, which may be of any suitable stiffness and weight, for vibrating at ultrasonic frequencies. For example, the elongated polygon transducer membrane 160 may be both stiff and light. For example, the elongated polygon transducer membrane 160 may be aluminum shim stock, metal-patterned Kapton, or any other metal-pattern film. The membrane may be impedance matched with the air to allow for more efficient air-coupling of the ultrasonic transducers.
Adjusting the rigidity of the conical structure 110, such as with the radial ribs shown in
The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit embodiments of the disclosed subject matter to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to explain the principles of embodiments of the disclosed subject matter and their practical applications, to thereby enable others skilled in the art to utilize those embodiments as well as various embodiments with various modifications as may be suited to the particular use contemplated.