What if you could recharge your phone just by walking? Some materials are capable of converting energy from one form to another, and these materials are already being implemented in the real world in a variety of applications.
Materials don’t just idly sit there; they interact with the energy around them and sometimes are capable of converting that energy into other forms. Piezoelectric materials are one example of a broader class of energy-converting materials that are already being used in various technologies and have the potential to become even more revolutionary.
Energy exists in many forms. Some of the most common forms are mechanical energy, exhibited by things like a moving vehicle; thermal energy, like the heat you feel from sunlight; electrical energy, associated with the movement or separation of electrical charges; and light energy, a form of electromagnetic radiation. The key idea is that certain materials have internal structures that allow them to transform energy. Piezoelectricity is the process in which materials that are subjected to mechanical stress create an electrical voltage.
Where the voltage comes from
The key to piezoelectricity lies in how certain materials, often crystals, have an uneven distribution of electric charge in their structures. These materials have what are called non-centrosymmetric structures. Though that sounds like a complicated term, it just means that the material’s internal structure doesn’t have a center of symmetry.
When the material is deformed, this lack of symmetry causes an imbalance in charges as the positions of positive and negative charges shift relative to each other. This creates a net electric polarization, or an overall separation of positive and negative charges across the material. This separation of charges is what creates the electrical voltage.
Where piezoelectric materials are used
Piezoelectric materials are quite useful in various technologies. For example, they are used in sensors that convert pressure or sound into electrical signals—in some microphones, they convert sound waves into voltage. They can also be used in medical imaging, both to generate sound waves when an electrical current is applied and to convert those echoes back into electrical signals.
These materials are also used in everyday objects like a lighter, where a piezoelectric material generates a spark to start the flame. What’s even cooler is that piezoelectricity could play a huge role in green energy in the future. As a first step in exploring the applications of piezoelectric materials, countries like Japan have already implemented piezoelectric floor tiles in high-traffic areas that generate electricity.
More than piezoelectricity
Piezoelectricity is just one type of energy-converting material. Other types include thermoelectric materials, which convert heat into electricity, and photovoltaic materials, which are used in solar panels to convert light into electricity.
Regardless of the type, these energy-converting materials are essential to many aspects of the modern world, including technology and sustainable energy. They show how materials aren’t just simple building blocks for the world around us, but that they can also actively convert energy in useful ways. Piezoelectricity specifically allows seemingly mundane actions like moving or walking to become small but meaningful sources of energy.