Nonlinear, detection of biodegradable, experimental nanoparticles using a high frequency ultrasound prototype

This work investigates high frequency ultrasound detection of two experimental contrast nanoparticles (FTAC: 400-nm diameter, polymer-coated perfluoro liquid core nano emulsion and PLGA, 100-130 nm diameter polymeric nanocapsules with a liquid perfluorooctyl bromide core) and compares nonlinear features of their response with those of a commercially available microbubbles (Sonovue®). Conventional and nonlinear sequences (pulse-inversion, PI and multi-pulse inversion, PIAM) and sub-harmonic pulse sequences were implemented in MATLAB and C++ in a high-frequency prototype [1] with a 32-MHz transducer. Gaussian-enveloped burst sequences at 20 MHz and 40MHz were transmitted at peak negative pressures from 0.3 1.3 MPa with the transducer focused in the lumen of a 180-μm diameter cellulose fiber. The nonlinear, high-frequency pulse sequences implemented in this work suppressed fundamental response and improved harmonic detection of tested particles.