Smart Materials & Structures

Biography

Biography: Elias Siores

Abstract

For energy harvesting from human movement, fibre based electrical power generators are highly desirable as they are light weight and comfortable and look no different from the conventional fabrics. The conjunction of piezoelectric materials in fibres and therefore fabrics offers a simple route for the building of soft piezoelectric generators. The flexible textile structures can themselves be designed so as to provide piezoelectric output on low levels of strains and loadings while providing high fatigue resistance under a large number of variable mechanical deformation and loading cycles. In this work, we demonstrate “3D spacer” technology based all-fibre piezoelectric fabrics as power generators and energy harvesters (Figure 1(a)). The single step knitted structure consisting of high β-phase (~80%) piezoelectric PVDF produced using conventional melt spinning under high electric field (0.6 MV/m) are knitted together with Ag coated PA66 yarns acting as the top and bottom electrodes. The novel and unique textile structure provides an output power density in the range of 1.10-5.10 μWcm-2 at applied impact pressures in the range of 0.02-0.10 MPa, providing significantly higher power outputs and efficiencies over the existing 2D woven and nonwoven piezoelectric structures (Figure 1(b)). The all fibre piezoelectric fabric possesses the advantage of efficient charge collection due to intimate contact of electrodes and uniform distribution of pressure on the fabric surface, leading to enhanced performance. Furthermore, an substantial increase in piezoelectric output of the PVDF yarns has been achieved using ZnSnO3 based perovskite which has doubled the piezoelectric constant from 60 pm/V to nearly 130 pm/V. Bearing all these merits in mind, we believe our method of producing large quantities of high quality piezoelectric yarn and piezoelectric fabric provides an effective option for the development of high performance energy-harvesting textile structures for electronic devices that could be charged from ambient environment or by human movement. Furthermore, via the creation of hybrid photovoltaic films and fibres, energy can be captured from solar radiation and used where the mechanical impetus is absent. The high energy efficiency, mechanical durability and comfort of the soft, flexible and all-fibre based power generator is highly attractive for a variety of potential applications such as wearable electronic systems and energy harvesters charged from ambient environment or by human movement.