Figure 1. Design and delivery of pulsed ultrasound waveforms for somatosensory stimulation.

(A) Example of experimental setup implemented to achieve peripheral ultrasonic stimulation (PUNS). Note the illustrations are not drawn to scale. (B) Illustration of the waveform strategy used to generate the PUNS-M stimulus, which elicited a brief mechanical buzzing sensation. The top-black trace illustrates a one volt peak-to-peak (V_p-p) square-wave signal originating from channel two (CH 2) of the function generator to drive acoustic pulses. Each pulse contained 700 cycles occurring at a frequency of 0.35 MHz. This voltage waveform was fed into the input of the RF amplifier as shown in A above. A single ultrasound pulse emitted from the transducer is shown at right (MPa  =  megapascals; PD  =  pulse duration). The bottom-blue trace illustrates 35, five V_p–p square-waves originating from channel one (CH 1) of the function generator. The signal generated by CH1 served as the pulse repetition frequency waveform and was used to trigger each CH2 pulse. (C) An intensity plot showing the lateral (XY) acoustic output profile from the ultrasound transducer during a PUNS-M waveform is shown using a pseudo-color look-up table. (D) Similar to C, a pseudo-color intensity plot illustrates the acoustic power delivered from the ultrasound transducer during a PUNS-M waveform as a function of lateral distance across the face of the transducer, as well as axial distance from the face of the transducer.