Research on the second-harmonic focused ultrasonic device based on micro-bubble contrast agents

Non-invasive, accurate diagnosis and treatment have increasingly gained attention in medical research. The nonlinear response mechanism of ultrasound contrast agents and their medical application have become major topics in ultrasound imaging studies. This paper reports on a second-harmonic focused ultrasonic device based on micro-bubble contrast agents, which is designed to solve the problems associated with a weak second-harmonic intensity. A periodic array of circular holes is embedded in the center of a specifically shaped resin plate, and contrast agents are encapsulated in the circular holes using thin resin tape. The functional mechanism is theoretically explained and experimentally verified. This device enables second-harmonic ultrasound imaging with a higher ultrasonic lateral resolution and signal-to-noise ratio than the conventional system without the device.