Indian Institute of Technology Bombay researches to come up with a Novel piezoelectric material.
Sradha Subash A
Nowadays, air travel has become comfortable for passengers due to the less vibrations from seats in the cabin. For dampening the vibrations from the huge aircraft turbine engines and the surrounding atmosphere, engineers installed palm-sized devices on the aircraft wings and cabin windows. These palm-sized devices are made up of piezoelectric materials, which are usually used to generate a large 'vibration-cancelling force', when an electric signal is applied.
Piezoelectric materials are used as sensors for moving parts that are controlled by electrical signals in the micrometre or nanometre range. Recently, researchers from IIT (Indian Institute of Technology Bombay) have proposed a piezoelectric material which is having better response than the frequently used piezoelectric ceramics. What they meant by 'better response' is that the material has the capacity to produce large force from a small input electric signal. Now, their research, which was partially supported by IIT Bombay, got published in European Journal of Mechanics -AlSolids.
Graphene Reinforced Composite (GRPC), the novel material which they put forward has fibres of PZT (lead zirconate titanate). It is often used as a piezoelectric material. The graphene nanoparticles are embedded in an epoxy base. Since PZT is brittle, it requires epoxy to enhance the material's strength. Susmita Naskar, a Prof at IIT Bombay, explained that she chose epoxy, since this material is easily available in the market and is easy to handle.
The purpose of a piezoelectric material is to
provide high piezoelectric response. Also it should have a high elastic
coefficient, so that whenever vibration dampers on an aircraft, the device
produces a larger force for the same quantity of electric signal and this keeps
it stiff by maintaining the shape. Prof Naskar elaborated that the difference
between a high and low elastic coefficient material is the same as that of the
difference between Aluminium and Rubber. Therefore, a high elastic coefficient
material is far better to be used in devices where larger opposing force is
required.
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The team studied the piezoelectric response as well as elastic coefficient of GRPC using both theoretical and computational models. Theoretical models calculated the properties of materials by analysing the characteristics of each constituent material and their proportions. Some models also considered the interactions of various components with each other. Even Though the theoretical models can provide quick analysis, they are still bounded by assumptions which need to be explored further. Dr. Kishor Balasaheb Shigare from the same institution added that their computations are important since those models accounted for the various shapes and orientations of PZT fibre and graphene nanoparticles.
Dr Shingare examined and compared the properties of both GRPC and the conventional PZT-epoxy material which is a piezoelectric ceramic. In order to inspect for stress developed in the material, they applied an electric field and stretched the materials in different directions within the simulation. The observation that the conventional PZT-epoxy materials are better than GRPC, in both piezoelectric and elastic properties. Due to the presence of graphene, deformation in GRPC is difficult which helps GRPC devices to remain rigid and to maintain their shape even when double the force is produced in presence of an electric field. As Dr. Shingare explained, graphene is a light material, still it is stiff. Also, it has a large surface area for interaction with PZT fibre and epoxy and hence it contributes to the improved effective properties in GRPC.
In previous research, the piezoelectric response was studied only in the plane of the device but this work looks at the piezoelectric response in all possible directions. Prof. Naskar commented that they viewed a significant increase in the piezoelectric response of GRPC while considering every direction. This could be applied in artificial muscles of biomedical devices since it requires movements in multiple directions.
In future, this study might be helpful in making more effective piezoelectric-based devices. Researchers think that GRPC can be used to build robots or satellites where the demand for light materials which can serve multiple purposes are high.