Piezoelectric materials, mainly ceramics, have extensively been used in sensing and energy harvesting due to their capacity to transform mechanical energy into electrical energy. Piezoelectric composites composed of piezoceramic embedded in an insulator polymer were found to conjugate mechanical flexibility and high electro-mechanical coupling constants [
1]. The polarization process may be hampered due to the polymer’s low dielectric constant and the non-continuity of the ceramic [
1]. Conductive carbon nanoparticles can counteract dielectric discrepancies, while the low connection between the piezoelectric particles remains unknown. State-of-the-art highly porous 3D networks of carbon have recently been developed and are believed to overcome these setbacks [
2]. The purpose of this work is to fabricate an innovative piezoelectric material using a 3D graphite network filled with barium titanate, all impregnated by a biobased polymer.
A barium titanate synthesis was perfected through hydrothermal synthesis (conventional and microwave-assisted) at mild temperatures (200 °C) by studying the effect of different reaction times on the tetragonality of the particles. The evaluation of the structural phase was conducted using X-ray diffraction and Raman spectroscopy, while the morphology was studied using scanning electron microscopy. The barium titanate particles were impregnated into the carbon foam using an optimized water suspension, with and without the assistance of voltage, which is thought to accelerate and facilitate the impregnation flow. A chitosan/zein polymer was used to incorporate the resulting apparatus to provide the flexibility needed in the final device. Built-in electrodes were used to test the electrical output given by this device. Piezoresponse force microscopy (PFM) was used to characterize the piezoelectric response of the particles after impregnation. The relationship between structure and overall piezoelectric output will be discussed.
Author Contributions
Conceptualization, P.F., D.F. and P.M.V.; methodology, P.F., M.I. and P.M.V.; investigation, M.R., Y.L., A.B.; resources, P.F.; writing—original draft preparation, M.R., P.F.; writing—review and editing, P.F., M.I.; porous thin graphite substrate fabrication, Y.L. and D.F.; supervision, P.F., M.I.; project administration, P.F.; funding acquisition, P.F. All authors have read and agreed to the published version of the manuscript.
Funding
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 and LA/P/0006/2020 and financed by national funds through the FCT/MEC (PIDDAC). Projects NANOTRONICS (IF/00300/2015), PIEZOFLEX (UTA-EXPL/NPN/0015/2019), and FLEXIDEVICE (PTDC/CTM-CTM/29671/2017) are also acknowledged. The project is supported by Welch Foundation (Grant No. F-1734) in part to D.F. Project supported by the UT-Portugal Research Program to P.F and D.F.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
References
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