Poly(vinylidene difluoride) (PVDF)
has become the polymer matrix
of choice for fabrication of wearable electronics and physiological
monitoring devices. Despite possessing a high piezoelectric constant,
additives are required to increase the charge transfer from PVDF matrix
to connected signal readout units. Many of these additives also stabilize
the β-phase of PVDF, which is associated with highest piezoelectric
coefficients. However, most of the additives used are often brittle
ceramic-phase materials resulting in decreased flexibility of the
devices and offsetting the gain in β-phase content. Intrinsically
conducting polymers (ICP), on the other hand, are ideal candidates
to improve the device-related properties of PVDF, due to their higher
flexibility than ceramic fillers as well as ability to form conducting
network in PVDF membranes. This work reports the performance and device
feasibility of PVDF–polycarbazole (PCZ) electrospun nanofiber
membranes. A higher β-phase was observed by FTIR spectroscopy
in PVDF/PCZ compared to other PVDF phases. Moreover, a higher open-circuit
potential was recorded over PVDF/polyaniline composites, which were
studied for comparison. The addition of PCZ reduced the flexibility
of pure PVDF nanofibers by 20% only. Besides, the work investigated
the bacterial biofouling and cell compatibility of the matrix, as
essential properties to examine any putative medical device application.
PVDF/PCZ membranes were then used to develop a nanogenerator, which
was capable of instantly lighting an entire LED array employing the
rectified output power, and charged up a 2.2 μF capacitors using
a bridge rectifier through a vertical compressive force applied periodically.
Finally, the nanogenerator demonstrated electrical energy harvesting
from movements of various parts of the human body, such as toe and
heel movement and wrist bending. In conclusion, PCZ can be considered
as an attractive, biocompatible, and anti-biofouling conducting polymer
for electrical actuation and flexible electronic device applications.