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

Tube-type double-parabolic-reflector ultrasonic transducer (T-DPLUS)

“…In Model 2, the 1st and 2nd reflector shapes are represented by Eqs. ( 6) and (7), respectively, and the focal point of these parabolas is the point ð0; 3Þ. Note that Z is the axial coordinate and R is the radial coordinate (both in millimeters), as shown in Fig.…”

“…However, a BLT has only a single working frequency lower than several hundred kilohertz, which limits the application possibilities. Recently, Chen et al studied a double-parabolic-reflector ultrasonic transducer (DPLUS) [4][5][6][7], which consists of a lead zirconate titanate (PZT) ring, double-parabolic reflectors (1st and 2nd reflectors), which share the same focal point, and a thin waveguide. The 1st reflector focuses the incident plane wave from the PZT ring, and the 2nd reflector reflects the ultrasound and turns it into an in-phase plane wave, which propagates into the thin waveguide.…”

“…These characteristics are difficult to achieve with conventional transducers containing BLTs. Hence, DPLUS expands potential applications of ultrasonic technology in various fields, such as ultrasound therapeutics [7], medical imaging, and ultrasonic tweezers.…”

“…One of the most promising applications of DPLUS is minimally invasive treatment (MIT), in which a thin needle is inserted through a surgical incision into the treatment target, and energy, such as radiofrequency, microwave, laser, or ultrasound, is directly delivered to ablate the target [7]. Ultrasound-based MIT has multiple treatment mechanisms, such as cavitation, direct mechanical impact, and thermal effects, according to the tissue type and working frequency [8,9], and various ultrasound applicators have been studied [10,11].…”

“…Ultrasound-based MIT has multiple treatment mechanisms, such as cavitation, direct mechanical impact, and thermal effects, according to the tissue type and working frequency [8,9], and various ultrasound applicators have been studied [10,11]. Because DPLUS has characteristics suitable for MIT, high-power and localized ultrasound through a thin waveguide, MIT with DPLUS is promising [7]. However, in actual use, conventional DPLUS may be challenging for sensing physical phenomena near the tip, such as sound pressure, temperature, and optical imagery.…”