ULTRASONIC TRANSDUCERS FOR PERIPHERAL NERVE REGENERATION STUDIES

Abstract

This thesis examined the design, fabrication, and characterization of piezoelectric- based ultrasonic platforms for the study of mechanically-stimulated peripheral nerve regeneration. The effect of ultrasound generated by piezoelectric cantilever transducers on cell culture environment was examined using dye and neutrally buoyant beads. Both studies showed mechanical energy generated by the piezoelectric cantilever transducers could be transmitted into the cell culture environment to potentially affect cell behavior. Thin-film transducers based on the piezoelectric polymer polyvinylidine fluoride (PVDF) were also designed given the ability to potentially assemble the material into a nerve guidance channel. Alternatively, a novel composite material of poly(lactic-co-glycolic acid (PLGA) containing peptide nanotubes was also examined for potential thin-film transducers. Impulse response measurements obtained from the thin-film devices showed a clear difference between poled and un- poled films when actuated at 20 Hz. X-ray diffraction measurements suggest that the PVDF exhibited a crystalline structure that could be made polar. Studies with the nanotube composite material indicated the weight fraction of the nanotubes <1 wt% failed to generated measurable piezoelectric response in the bulk material suggest- ing the bulk PLGA film could be made piezoelectric by using a more concentrated nanotube network.