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David Guinovart, PhD, Assistant Professor at The Hormel Institute, University of Minnesota, has co-authored a paper published in the International Journal of Engineering Science.

The paper “Influence of nonlocal elasticity tensor and flexoelectricity in a rod: An asymptotic homogenization approach” provides a new methodology for studying flexoelectric composite materials and unlocks insights into their vast possible applications, such as for the development of intelligent sensors, biomedical devices, more eco-friendly energy sources, and more.

Imagine being able to charge your phone just by bending it slightly, or a future where skyscrapers generate their power merely through the sway of their structures. Imagine sensors and actuators in robotics that power themselves through their own motion. Now, extend that imagination to the human body, where the tissues, like bones, harness this power to heal and regenerate naturally and more effectively. These aren’t scenes from a science fiction movie. This is the real, exciting world of flexoelectricity.

Although flexoelectricity has been recognized as a material property for several decades, it still needs to be further explored. Flexoelectricity is a scientific concept that reveals the relationship between the shape of a material and its electrical properties. When materials are bent, compressed, or twisted, they can generate an electrical charge.

“Flexoelectricity is more than a scientific curiosity: it’s a gateway to a future where energy is seamlessly integrated into our daily lives and even our biology. From powering gadgets to healing bones, it represents a harmony between technology and nature and the endless possibilities that arise when they intersect,” Guinovart said. “As we continue exploring flexoelectricity, we’re not just uncovering new ways to generate power; we’re redefining the relationship between energy, technology, and the human body.”

At the heart of this phenomenon is the atomic structure of materials. When materials change in shape or size due to force (deformation), the atoms inside are displaced, creating an imbalance in electrical charges and an electric current. This is like creating energy from physical movement.

Research has shown that bones exhibit flexoelectric properties when subjected to stress or strain, like during walking or lifting: flexoelectricity could be key to understanding how bones heal and regenerate. When a bone fractures, the natural flexoelectricity could stimulate the healing process, guiding the growth and repair of bone tissue. This opens up possibilities for medical treatments, where harnessing flexoelectricity could lead to more effective and natural healing methods.

The potential applications of flexoelectricity are vast. They could be used in energy harvesters, capturing energy from everyday activities. The act of walking or the pressure of vehicles on roads could be transformed into electrical power, steering us toward a sustainable future.

Understanding flexoelectric materials and structures is crucial yet complex, because many structures are like a patchwork quilt of various materials with unique mechanical and electrical characteristics. To make sense of this complexity, scientists use a technique called homogenization. It’s like making a smoothie: as you blend different fruits to create a uniform flavor, homogenization blends the properties of all the other materials to form a new “average” structure. This “average” structure is easier to study because it represents a mix of all its components. So, in science, homogenization takes a complex material made of many different parts and simplifies it, allowing us to understand and use it better.

The research team used a new way to study how materials generate electricity when bent or pressed. This method, called the asymptotic homogenization method (AHM), is beneficial for understanding mixed materials.

The researchers focused on a simple model: a rod that shows flexoelectric properties. They discovered that the way these materials are made up — the tiny differences and details in their composition — matters in how they behave and generate electricity when bent. It’s like finding out that the specific way you mix ingredients in a recipe can change the taste of a cake. This study showed that the flexibility and makeup of a material are critical to how well it can produce electricity when it’s bent or squeezed.