Abstract: This application relates to the technical field of coal-fired boilers, and provides a method and an apparatus for improving steam oxidation resistance of a small-diameter boiler tube in a coal-fired boiler. The method includes the following steps: cutting a boiler tube panel from a ceiling of the boiler, vertically hoisting and fixing the boiler tube panel, and cutting out a section from a bottom portion of a lower bend of the boiler tube panel; cleaning an inner tube wall of each tube body in the boiler tube panel; performing oxidation resistance coating sintering on the inner tube wall of each tube body in the boiler tube panel; and performing a welding repair on each tube body in a sintered boiler tube panel. All construction processes of this method can be completed in a furnace during shutdown and maintenance, production efficiency is high, and maintenance duration can be significantly reduced.

Abstract: In some examples, a method of fabricating a transducer includes disposing a plurality of anchors on a substrate and disposing a sealing material and a device layer over the anchors and the substrate to form a cavity, the sealing material sealing the cavity. The method may further include forming, in the device layer, a plate and at least one spring member. The at least one spring member may be supported by at least one anchor of the plurality of anchors, and the at least one spring member may support the plate to allow relative movement between the plate and the substrate.

Abstract: In some examples, a CMUT may include a plurality of electrodes, and each electrode may include a plurality of sub-electrodes. For instance, a first sub-electrode and a second sub-electrode may be disposed on opposite sides of a third sub-electrode. In some cases, a first bias voltage may be applied to the third sub-electrode and a second bias voltage may be applied to the first and second sub-electrodes while causing at least one of the first sub-electrode, the second sub-electrode, or the third sub-electrode to transmit and/or receive ultrasonic energy. For example, the second bias voltage may be applied at a different voltage amount than the first bias voltage, and/or may be applied at a different timing than the first bias voltage.

Abstract: In some examples, a capacitive micromachined ultrasonic transducer (CMUT) includes a first electrode and a second electrode, with the second electrode being opposed to the first electrode. A bias voltage may supply a bias voltage to the second electrode. In addition, a first capacitor may include a first electrode electrically connected to the first electrode of the CMUT, and the first capacitor may have a second electrode electrically connected to a transmit/receive circuit. Furthermore, a first resistor may have a first electrode electrically connected to the first electrode of the first capacitor and the first electrode of the CMUT. The first resistor may include a second electrode electrically connected to a common return path.

Abstract: In some examples, a CMUT array may include a plurality of elements, and each element may include a plurality of sub-elements. For instance, a first sub-element and a second sub-element may be disposed on opposite sides of a third sub-element. In some cases, the third sub-element may be configured to transmit ultrasonic energy at a higher center frequency than at least one of the first sub-element or the second sub-element. Further, in some instances, the sub-elements may have a plurality of regions in which different regions are configured to transmit ultrasonic energy at different resonant frequencies. For instance, the resonant frequencies of a plurality of CMUT cells in each sub-element may decrease in an elevation direction from a center of each element toward the edges of the CMUT array.

Abstract: In some examples, a capacitive micromachined ultrasonic transducer (CMUT) includes a first electrode and a second electrode. The CMUT may be connectable to a bias voltage supply for supplying a bias voltage, and a transmit and/or receive (TX/RX) circuit. In some cases, a first capacitor having a first electrode may be electrically connected to the first electrode of the CMUT, the first capacitor having a second electrode that may be electrically connected to the TX/RX circuit. Furthermore, a first resistor may include a first electrode electrically connected to the first electrode of the first capacitor and the first electrode of the CMUT. A second electrode of the first resistor may be electrically connected to at least one of: a ground or common return path, or the second electrode of the first capacitor.

Abstract: A capacitive micromachined ultrasound transducer (cMUT) is provided. The cMUT has a first layer having a first electrode and a second layer having a second electrode opposing the first electrode to define a gap width therebetween. At least one of the first layer and the second layer includes a flexible layer having a contact area in contact to a support, such that the first electrode and the second electrode are movable relative to each other to cause a change of the gap width. The support has two substantially continuous shoulder sides each extending along with the flexible layer, each shoulder side making graduated contact with more contact area of the flexible layer as the flexible layer deforms toward the shoulder side, causing the flexible layer to have a dynamically changing spring strength.

Abstract: In some examples, a capacitive micromachined ultrasonic transducer (CMUT) apparatus includes one or more CMUTs formed on a CMUT substrate to have an operational direction facing away from the CMUT substrate. A first layer of a first material is disposed over the one or more CMUTs for passing acoustic energy to or from the one or more CMUTs in the operational direction. The first layer may be a solid, liquid, gel, or colloid. Further, a second layer of a second material may be disposed over the first layer and may be a different material from the first material. In some cases, the second layer may be a solid with an inner surface having a curvature facing the first layer. Additionally, or alternatively, in some cases, the acoustic impedance of the first material and the second material may be between 1 and 2 MRayl.

Abstract: In some examples, a method of fabricating a transducer includes disposing a plurality of anchors on a substrate and disposing a sealing material and a device layer over the anchors and the substrate to form a cavity, the sealing material sealing the cavity. The method may further include forming, in the device layer, a plate and at least one spring member. The at least one spring member may be supported by at least one anchor of the plurality of anchors, and the at least one spring member may support the plate to allow relative movement between the plate and the substrate.

Abstract: In some examples, a capacitive micromachined ultrasonic transducer (CMUT) includes a first electrode and a second electrode. The CMUT may be connectable to a bias voltage supply for supplying a bias voltage, and a transmit and/or receive (TX/RX) circuit. In some cases, a first capacitor having a first electrode may be electrically connected to the first electrode of the CMUT, the first capacitor having a second electrode that may be electrically connected to the TX/RX circuit. Furthermore, a first resistor may include a first electrode electrically connected to the first electrode of the first capacitor and the first electrode of the CMUT. A second electrode of the first resistor may be electrically connected to at least one of: a ground or common return path, or the second electrode of the first capacitor.

Abstract: In some examples, a CMUT may include a plurality of electrodes, and each electrode may include a plurality of sub-electrodes. For instance, a first sub-electrode and a second sub-electrode may be disposed on opposite sides of a third sub-electrode. In some cases, a first bias voltage may be applied to the third sub-electrode and a second bias voltage may be applied to the first and second sub-electrodes while causing at least one of the first sub-electrode, the second sub-electrode, or the third sub-electrode to transmit and/or receive ultrasonic energy. For example, the second bias voltage may be applied at a different voltage amount than the first bias voltage, and/or may be applied at a different timing than the first bias voltage.

Abstract: In some examples, a transducer apparatus includes a spring structure that enables a large, reliable amount of displacement of a transducer plate. For instance, an individual cell of the transducer apparatus may include a substrate having a first electrode portion, with at least one spring anchor extending from a first side of the substrate. At least one spring member may be supported by the at least one anchor, and may be connected to a plate that includes a second electrode portion. Accordingly, the spring member may support the plate, at least in part, for enabling the plate to move in a resilient manner toward and away from the substrate. In some cases, the spring member may be a bar-shaped spring that is cantilevered to an anchor or supported by two or more anchors. Additionally, a cavity between the plate and the substrate may be sealed by a sealing material.

Abstract: In some examples, a capacitive micromachined ultrasonic transducer (CMUT) apparatus includes one or more CMUTs formed on a CMUT substrate to have an operational direction facing away from the CMUT substrate. A first layer of a first material is disposed over the one or more CMUTs for passing acoustic energy to or from the one or more CMUTs in the operational direction. The first layer may be a solid, liquid, gel, or colloid. Further, a second layer of a second material may be disposed over the first layer and may be a different material from the first material. In some cases, the second layer may be a solid with an inner surface having a curvature facing the first layer. Additionally, or alternatively, in some cases, the acoustic impedance of the first material and the second material may be between 1 and 2 MRayl.

Abstract: A method for a capacitive micromachined ultrasound transducer (cMUT) is provided. The method grows and patterns a diffusion barrier layer over a surface of a base layer. The diffusion barrier layer have different areas that allow different levels of diffusion penetration. A diffusion process is performed over the diffusion barrier layer such that a diffusion reactivated material reaches different depths into the base layer below the different areas. A anchor is formed using the diffusion reactivated material. The anchor has a lower portion below a major surface of the base layer and an upper portion above the major surface of the base layer. A cover layer is placed over the anchor and the base layer. At least one of the cover layer and the base layer includes a flexible layer, such that the cMUT electrodes are movable relative to each other to cause a change of the gap width.

Abstract: In some examples, a capacitive micromachined ultrasonic transducer (CMUT) apparatus includes one or more CMUTs formed on a CMUT substrate to have an operational direction facing away from the CMUT substrate. As one example, the one or more CMUTs may include a plurality of CMUT cells arranged in groups to form CMUT elements, and a plurality of the CMUT elements may be configured as an array on the CMUT substrate. An acoustic window is disposed over the one or more CMUTs and may contact an external medium. For instance, the acoustic window may be positioned to pass acoustic energy to or from the one or more CMUTs in the operational direction. A coupling medium may be disposed between the CMUTs and the acoustic window to couple acoustic energy between the one or more CMUTs and the acoustic window.

Abstract: A method as disclosed makes a capacitive micromachined ultrasonic transducer (cMUT). The method forms a pattern of standing features on a substrate to serve as support walls in the cMUT being made, and further makes a patterned trench from the front side into the substrate at selected locations where separation boundaries of neighboring elements of the cMUT are located. In the process of completing the transducer elements of the cMUT, the method forms a covering layer over the patterned trench to at least temporarily cover the patterned trench. The covering layer seals the patterned trench to prevent other materials from entering during at least a part of the fabrication process.

Abstract: In some examples, a CMUT array may include a plurality of elements, and each element may include a plurality of sub-elements. For instance, a first sub-element and a second sub-element may be disposed on opposite sides of a third sub-element. In some cases, the third sub-element may be configured to transmit ultrasonic energy at a higher center frequency than at least one of the first sub-element or the second sub-element. Further, in some instances, the sub-elements may have a plurality of regions in which different regions are configured to transmit ultrasonic energy at different resonant frequencies. For instance, the resonant frequencies of a plurality of CMUT cells in each sub-element may decrease in an elevation direction from a center of each element toward the edges of the CMUT array.

Abstract: Ultrasonic scanners and methods of manufacturing ultrasonic scanners. One embodiment of a method includes integrating a flexible electronic device (e.g. an IC) and a flexible ultrasonic transducer (e.g. a portion of a circular CMUT array) with a flexible member. The IC, the transducer, and the flexible member can form a flexible subassembly which is rolled up to form an ultrasonic scanner. The integration of the IC and the transducer can occur at the same time. In the alternative, the integration of the electronic device can occur before the integration of the transducer. Moreover, the integration of the transducer can include using a semiconductor technique. Furthermore, the rolled up subassembly can form a lumen or can be attached to a lumen. The method can include folding a portion of the flexible subassembly to form a forward looking transducer. The flexible member of some subassemblies can include a pair of arms.

Abstract: A capacitive micromachined ultrasound transducer (cMUT) and fabrication method of the same are provided. The cMUT has a substrate, a curved membrane disposed on top of the substrate, and a flexible membrane disposed on top of the curved membrane. The curved membrane has a raised portion which is higher than a recessed portion relative to the substrate, and is supported by a support standing on a major surface of the substrate. The flexible membrane includes a first region mounted to the raised portion of the curved membrane, and a second region extending over the recessed portion of the curved member. Methods for fabricating the cMUT are also disclosed.

Abstract: In some examples, a capacitive micromachined ultrasonic transducer (CMUT) apparatus includes one or more CMUTs formed on a CMUT substrate to have an operational direction facing away from the CMUT substrate. As one example, the one or more CMUTs may include a plurality of CMUT cells arranged in groups to form CMUT elements, and a plurality of the CMUT elements may be configured as an array on the CMUT substrate. An acoustic window is disposed over the one or more CMUTs and may contact an external medium. For instance, the acoustic window may be positioned to pass acoustic energy to or from the one or more CMUTs in the operational direction. A coupling medium may be disposed between the CMUTs and the acoustic window to couple acoustic energy between the one or more CMUTs and the acoustic window.