By Rashi Tiwari – Updated Mar 24, 2022
The piezoelectric effect is a property of certain materials that convert mechanical stress into electrical voltage. The term "piezo" comes from the Greek word for "to squeeze." First observed by Pierre and Jacques Curie in 1880, this phenomenon was later shown to exist in bone by Dr. I. Yasuda in 1957.
Direct piezoelectricity refers to the generation of voltage when a material is compressed or stretched. Inverse piezoelectricity describes the mechanical deformation of a material—such as bending of ceramics or crystals—when an electric field is applied.
Bones are a composite of inorganic hydroxyapatite crystals and organic type‑I collagen fibers. Hydroxyapatite, with its crystalline structure, is the key contributor to the piezoelectric behavior of bone. When mechanical forces deform collagen molecules, charged carriers migrate to the bone surface, creating an electric potential across the tissue.
Mechanical stress on bone triggers a localized electric field. This field establishes electrical dipoles that attract osteoblasts—the cells responsible for bone formation. The resulting mineral deposition, primarily calcium, strengthens the bone on the stressed side, thereby increasing overall bone density.
External electrical stimulation has been shown to accelerate bone healing and repair. The piezoelectric effect offers a natural mechanism for bone remodeling, aligning with Dr. Julius Wolff’s observations from 1892 that bone adapts its shape in response to mechanical forces—a principle now known as Wolff’s law.
Understanding and harnessing bone’s piezoelectric properties can inform therapeutic strategies for osteoporosis, fracture repair, and regenerative medicine.
