Piezoelectric Microstructured Fibers via Drawing of Multimaterial Preforms

We demonstrate planar laminated piezoelectric generators and piezoelectric microstructured fibers based on BaTiO3-polyvinylidene and carbon-loaded-polyethylene materials combinations. The laminated piezoelectric generators were assembled by sandwiching the electrospun BaTiO3-polyvinylidene mat between two carbon-loaded-polyethylene films. The piezoelectric microstructured fiber was fabricated via drawing of the multilayer fiber preform, and features a swissroll geometry that have ~10 alternating piezoelectric and conductive layers. Both piezoelectric generators have excellent mechanical durability, and could retain their piezoelectric performance after 3 day’s cyclic bend-release tests. Compared to the laminated generators, the piezoelectric fibers are advantageous as they could be directly woven into large-area commercial fabrics. Potential applications of the proposed piezoelectric fibers include micro-power-generation and remote sensing in wearable, automotive and aerospace industries.


As shown in
, when the BTO concentration is higher than 15%, α phase could be hardly observed. When the BTO concentration is lower than 10%, α phase and β phase coexist in the nanocomposite. The phase content, F( ), in the PVDF mats was calculated using the following Eq.: 29 Where and are the absorbance at 761 cm -1 and 840 cm -1 respectively, and is the degree of crystallinity of each phase. and are the absorption coefficient at the respective wavenumber, which are 6.1×10 4 and 7.7×10 4 cm 2 mol -1 . From calculation, we find that the β crystal phase content increased from 56% to 70%, when the BTO concentration increases from 0 to 10 wt%.

XRD of BTO-PVDF mats
The X-ray diffraction patterns were recorded by a Bruker D8/Discover diffractometer equipped with a standard sealed tube producing Cu radiation (λ = 1.54178 Å) running at 40 kV and 40 mA.
The peaks at 2θ values of 18.5°, 20.4° are indexed to the (020), (200/110) reflections of PVDF respectively 29,31 , while the other characteristic peaks can be assigned to the tetragonal phase of BaTiO3 33 .

Supplementary Figure 8| The XRD patterns of the PVDF mats featuring different BTO concentrations
For the nanocomposites, when the BTO concentration is lower than 15%, we can observe a weak peak at 20.4° (characteristic of the phase in PVDF). However, when the BTO concentration is higher than 15%, the two peaks that are characteristic to scattering in amorphous PVDF (see the left hand side of the bottom panel in Supplementary Fig. 8) cannot be clearly observed, which is ascribed to the shielding effect due to high intensity diffraction peaks in BTO nanocrystals.

Note 3. Mechanical analysis of the laminated generators under bending
Here we discuss in more details evaluation of strain in the bent laminated generators. Consider, for example, the second region in Fig. 4a of length 2 and suppose that it has a fixed curvature 1/ .