Fluid impermeable ultrasonic transducer

A method of forming a fluid impermeable ultrasonic transducer, the method comprising:

• forming a substantially hollow casing from a fluid impermeable material having an internal cavity and an open first end, wherein the fluid impermeable material comprises titanium;
• forming a transducer head element from the fluid impermeable material, the transducer head element being sized to connect with the open first end of the casing;
• forming a focusing lens on a front surface of the transducer head element, the focus lens configured to focus ultrasound towards a focal point;
• joining the head element with the first end of the casing to form a fluid impermeable joint, the head element positioned such that the focusing lens points away from the casing;
• bonding an actuator to a back surface of the transducer head element opposite the front surface, the actuator operable to generate oscillatory mechanical vibration of the focusing lens so that ultrasound is emitted from the focusing lens toward the focal point;
• forming a peripheral portion surrounding the focusing lens;
• and
• forming an attenuation layer interfaced with the peripheral portion, the attenuation layer configured to absorb ultrasonic energy emitted through the peripheral portion from the actuator, wherein the front surface of the transducer head comprises the peripheral portion and the attenuation layer.

A method of forming a fluid impermeable ultrasonic transducer, the method comprising:

• forming a substantially hollow casing from a fluid impermeable material having an internal cavity and a closed first end defining a transducer head element, wherein the fluid impermeable material comprises titanium;
• forming a focusing lens on a front surface of the head element, the focus lens configured to focus ultrasound towards a focal point;
• bonding an actuator to a back surface of the transducer head element opposite the front surface, the actuator operable to generate oscillatory mechanical vibration of the focusing lens so that ultrasound is emitted from the focusing lens toward the focal point;
• forming a peripheral portion surrounding the focusing lens;
• and
• forming an attenuation layer interfaced with the peripheral portion, the attenuation layer configured to absorb ultrasonic energy emitted through the peripheral portion from the actuator, wherein the front surface of the head element comprises the peripheral portion and the attenuation layer.

A method of ejecting droplets from a reservoir of fluid, the method comprising:

• with a fluid impermeable transducer comprising:
• a casing;
• a fluid impermeable transducer head comprising a metal focusing lens, wherein the fluid impermeable transducer head and the casing comprise titanium, the fluid impermeable transducer head having a back surface and a front surface, the metal focusing lens being disposed on the front surface and configured to focus ultrasound towards a focal point;
• and
• an actuator bonded to the back surface of the fluid impermeable transducer head and operable to generate oscillatory mechanical vibration of the metal focusing lens so that ultrasound is emitted from the metal focusing lens towards the focal point, wherein the casing and fluid impermeable transducer head are connected in a fluid impermeable manner to prevent ingress of liquid into the casing, wherein the front surface of the fluid impermeable transducer head comprises:
• a peripheral portion surrounding the metal focusing lens;
• and
• an attenuation layer interfaced with the peripheral portion and configured to absorb ultrasonic energy emitted through the peripheral portion from the actuator;
• immersing the metal focusing lens in an acoustic medium positioned to couple acoustic energy from the fluid impermeable transducer to the reservoir;
• generating an acoustic pulse by the actuator at a frequency configured to cause droplet ejection from a fluid surface of the reservoir;
• and
• passing the acoustic pulse from the actuator to the reservoir via the metal focusing lens.

A method of performing ultrasound testing of a structure, the method comprising:

• with a fluid impermeable transducer comprising:
• a casing;
• a fluid impermeable transducer head comprising a metal focusing lens, wherein the fluid impermeable transducer head and the casing comprise titanium, the fluid impermeable transducer head having a back surface and a front surface, the metal focusing lens being disposed on the front surface and configured to focus ultrasound towards a focal point;
• and
• an actuator bonded to the back surface of the fluid impermeable transducer head and operable to generate oscillatory mechanical vibration of the metal focusing lens so that ultrasound is emitted from the metal focusing lens towards the focal point, wherein the casing and fluid impermeable transducer head are connected in a fluid impermeable manner to prevent ingress of liquid into the casing, wherein the front surface of the fluid impermeable transducer head comprises:
• a peripheral portion surrounding the metal focusing lens;
• and
• an attenuation layer interfaced with the peripheral portion and configured to absorb ultrasonic energy emitted through the peripheral portion from the actuator;
• immersing the metal focusing lens in an acoustic medium in fluid contact with the structure;
• generating an acoustic pulse by the actuator and directed at a scanned region of the structure;
• receiving an echo of the acoustic pulse corresponding to the scanned region;
• and
• determining a physical parameter of the scanned region of the structure based on a characteristic of the echo.