Quasi-monopolar Ultrasound Pulse by Stack-layer Dual-frequency Ultrasound Transducer

Monopolar ultrasound pulse holds significant potential for high-resolution imaging and harmonic imaging. Here, we propose to generate a quasi-monopolar ultrasound pulse by superposition of two ultrasound signals from a stack-layer dual-frequency ultrasound transducer (1MHz / 3MHz). The experimental -6 dB pulse width of the negative pressure was 138 ns, indicating a sub-wavelength resolution imaging. Meanwhile, the ratio of the peak negative pressure and the peak positive pressure was 3.69, a highly beneficial property for super-harmonic ultrasound imaging. The quasi-monopolar and short pulse may enable advanced biomedical ultrasound imaging with high contrast and sub-wavelength resolution.