Tushar Shama, Sahil Naik, Jewel Langevine, Billy Gill, John X.J. Zhang, The University of Texas at Austin, The University of Texas Health Science Center at Houston, Dartmouth College, Volume 62, Issue 1, Page: 188-195
Flexible piezoelectric materials are emerging as a promising solution for developing a new class of sensors, especially for biomedical applications. Piezoelectric polymer PVDF (polyvinyledenedifluoride), in particular, has been conventionally drawn in to films either by melt casting or solvent casting. Recent studies highlight the enhanced piezoelectricity capability of nanostructures made out of PVDF-TrFE (tetrafluoroethylene). Higher piezoelectricity can allow better device performance as sensors, actuators and energy harvesters. However, there has been limited device development using such nanostructures. Even though higher piezoelectricity was demonstrated for PVDF nanofibers, the form factor and insulating nature of a nanofiber makes them unsuitable for practical application. In the present study, we solve this problem by fabricating novel core-shell structures using co-axial electrospinning. In addition, we elaborate on the technique to pattern high-density, highly aligned nanofibers. Lastly, we assembled pressure sensors utilizing these fiber structures for endovascular applications. The sensors were integrated on catheters and tested in-vitro under simulated physiological conditions. We observed significant improvements using core-shell electrospun fibers (4.5 times gain in signal intensity, 4000μV/mmHg sensitivity) over regular PVDF nanofibers (280μV/mmHg). The preliminary results showed that core-shell fiber based devices exhibit nearly 40 fold higher sensitivity, compared to the thin film structures without such structures demonstrated previously.
KEYWORDS: PVDF-TrFE, nanofibers, core-shell, pressure sensor, catheter