Design of a Multichannel Pulser/Receiver and Optimized Damping Resistor for High-Frequency Transducer Applied to SAM System

Abstract

Scanning acoustic microcopy (SAM) is widely used in biomedical and industrial applications in dermatology, ophthalmology, intravascular imaging, and small animal images, owing to SAM’s ability to photograph small structures with a good spatial resolution. One of the most important devices of this system is the pulser/receiver (P/R) (PRN-300, Ohlabs Corporation, Nam-gu Busan, Republic of Korea), which generates pulses to trigger a high-frequency transducer. This article presents the design of a pulse generator to excite high-frequency transducers with four channels. The characteristics of the pulses, such as time and frequency, can be reconfigured by using a high-speed field programmable gate array (FPGA). The configuration software was developed for communicating with the P/R device via a USB connector for easy, feasible pulse selection and real-time pulse management. Besides that, during the design and implementation of the hardware, we optimized the damping resistor value to reduce the overshoot and undershoot part of the signal, ensuring the best effect on the transducer signal. The test results show that unipolar pulses worked with transducers with frequencies over 100 MHz. The SAM systems can work simultaneously with multiple transducers, and the resulting images have different resolutions of regions.

Design and Micro-Fabrication of Focused High-Frequency Needle Transducers for Medical Imaging

“…Some previous studies [ 22 , 25 , 26 ] only applied the mass–spring technique on flat-surface transducers or lower 50 MHz focused transducers. The pulse–echo response method was used to test and evaluate the fabricated transducers, and the wire phantom experiment [ 27 , 28 , 29 ] was conducted to calculate the lateral and axial resolutions of the transducer and to demonstrate its performance. The fabrication and evaluation of focused needle transducers (100 MHz) was reported in this study.…”

Design of a High-Power Multilevel Sinusoidal Signal and High-Frequency Excitation Module Based on FPGA for HIFU Systems

“…The HIFU transducer converts stimulated electrical signals to create a focused ultrasound at one point and generate heat to burn cells. The HIFU controller board generates an electrical pulse signal to excite the HIFU transducer [13,14]. However, modern HIFU systems also incorporate other expansion devices, such as motion controllers or magnetic resonance imaging (MRI) systems, to increase the effectiveness of treatment [15,16].…”