Citation: Nowacki, B.; Jała, J.;
Mistewicz, K.; Przyłucki, R.;
Kope´c, G.; Stenzel, T. Flexible
SbSI/Polyurethane Nanocomposite
for Sensing and Energy Harvesting.
Sensors 2023, 23, 63. https://doi.org/
10.3390/s23010063
Academic Editor: Chang Kyu Jeong
Received: 15 November 2022
Revised: 14 December 2022
Accepted: 19 December 2022
Published: 21 December 2022
Copyright: © 2022 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Flexible SbSI/Polyurethane Nanocomposite for Sensing and
Energy Harvesting
Bartłomiej Nowacki
1,
* , Jakub Jała
1
, Krystian Mistewicz
2
, Roman Przyłucki
3
, Grzegorz Kope´c
3
and Tomasz Stenzel
3
1
Department of Materials Technologies, Faculty of Materials Engineering, Silesian University of Technology,
Krasi´nskiego 8, 40-019 Katowice, Poland
2
Institute of Physics—Center for Science and Education, Silesian University of Technology, Krasi´nskiego 8,
40-019 Katowice, Poland
3
Department of Industrial Informatics, Faculty of Materials Science, Silesian University of Technology,
Krasi´nskiego 8, 40-019 Katowice, Poland
* Correspondence: bartlomiej.nowacki@polsl.pl
Abstract:
The dynamic development of flexible wearable electronics creates new possibilities for the
production and use of new types of sensors. Recently, polymer nanocomposites have gained great
popularity in the fabrication of sensors. They possess both the mechanical advantages of polymers
and the functional properties of nanomaterials. The main drawback of such systems is the complexity
of their manufacturing. This article presents, for the first time, fabrication of an antimony sulfoiodide
(SbSI) and polyurethane (PU) nanocomposite and its application as a piezoelectric nanogenerator
for strain detection. The SbSI/PU nanocomposite was prepared using simple, fast, and efficient
technology. It allowed the obtainment of a high amount of material without the need to apply
complex chemical methods or material processing. The SbSI/PU nanocomposite exhibited high
flexibility and durability. The microstructure and chemical composition of the prepared material were
investigated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy
(EDS), respectively. These studies revealed a lack of defects in the material structure and relatively low
agglomeration of nanowires. The piezoelectric response of SbSI/PU nanocomposite was measured
by pressing the sample with a pneumatic actuator at different excitation frequencies. It is proposed
that the developed nanocomposite can be introduced into the shoe sole in order to harvest energy
from human body movement.
Keywords: nanocomposite; piezoelectric effect; flexible electronics; energy harvesting
1. Introduction
Flexible electronic devices possess numerous advantages over the conventional rigid
elements. Due to inherent bendability, stretchability, and twistability, flexible electronic
devices are attractive for use in medicine [
1
–
4
], energy storage or harvesting [
5
–
10
], robotics,
and smart clothing [
11
–
16
]. The materials for flexible electronics should exhibit remarkable
elasticity along with good resistance to fatigue damage originating from frequent strain
or stress influence. Their functional properties may refer to optical, electrical, or magnetic
characteristics depending on the relevant application of a material. In case of polymer
composites, the functional fillers are dispersed in a flexible matrix to achieve a material
with desirable mechanical properties and diminished (in comparison with pristine filler)
functional characteristics. A detection of mechanical deformation can be accomplished
using three fundamental phenomena: piezoresistive effect, strain-dependent electric capac-
itance variation, and piezoelectricity [
12
]. Among them, the piezoelectric effect is the most
promising for energy harvesting.
The human body generates a lot of energy through thermal radiation and movement.
Until now, various devices have been proposed for biomechanical energy harvesting
[17–19]
.
Sensors 2023, 23, 63. https://doi.org/10.3390/s23010063 https://www.mdpi.com/journal/sensors