Wideband Multimode Excitation by a Double-Parabolic-Reflector Ultrasonic Transducer

The Blossoming of Ultrasonic Metatransducers

Key requirements to boost the applicability of ultrasonic systems for in situ, real-time operations are low hardware complexity and low power consumption. These features are not available in present-day systems due to the fact that US inspections are typically achieved through phased arrays featuring a large number of individually controlled piezoelectric transducers and generating huge quantities of data. To minimize the energy and computational requirements, novel devices that feature enhanced functionalities beyond the mere conversion (i.e., metatransducers) can be conceived. This article reviews the potential of recent research breakthroughs in the transducer technology, which allow them to efficiently perform tasks, such as focusing, energy harvesting, beamforming, data communication, or mode filtering, and discusses the challenges for the widespread adoption of these solutions.

High-Power Ultrasonic Transducer for Effective Hemolysis

To realize compact and portable hemolysis devices, an ultrasonic transducer with a blood channel is proposed in this study. Ultrasound waves are focused by a parabolic reflector to generate high sound pressure inside the channel for hemolysis. The hemolysis performance of the transducer is evaluated using simulations and experiments. Experiments are performed with various voltages and flow rates to verify the feasibility of hemolysis. The hemolysis rate is more than 93% at an applied voltage of 80 Vp-p, a flow rate of 0.25 mL/min, and a driving frequency of 1.28 MHz.

Double-Parabolic-Reflectors Ultrasonic Transducer With Flexible Waveguide for Minimally Invasive Treatment

OBJECTIVE

To treat tissues that are difficult to access, ultrasound based minimally invasive treatment (MIT) is promising. However, high-power ultrasound delivery through waveguides had been difficult which can increase treatment duration. It is our effort to design the waveguide that can transmit powerful ultrasound.

METHODS

The waveguide with two parabolic reflectors was proposed by us to produce high-energy-density plane wave. Use of flexible and long thin waveguide was demonstrated here.

RESULTS

Double Parabolic refLectors wave-guided high-power Ultrasonic tranSducer (DPLUS) including a ϕ1 mm ×1 m Nitinol thin waveguide was fabricated. It was shown that high-power ultrasound between 1 to 2 MHz can be propagated through the thin waveguide. Low-loss waveguide material was confirmed to be important to enhance output. As ultrasound is transmitted into working medium, energy mainly flows from the side surface. Temperature of target soft tissue was demonstrated to drastically increase by 10 degree in 30 seconds.

CONCLUSION

The developed DPLUS makes high-power ultrasound transmission in long and flexible thin waveguide possible.

SIGNIFICANCE

The concept of DPLUS for delivering high-power ultrasound is powerful in the field of Ultrasonics.