A piezoelectric bimorph energy harvester is a device designed to convert mechanical vibrations or deformations into electrical energy using the piezoelectric effect. The piezoelectric effect is a phenomenon where certain materials generate an electric charge in response to applied mechanical stress or strain. In the case of a bimorph energy harvester, two piezoelectric materials with opposite polarity are bonded together, creating a bimorph structure.
The working principle of a piezoelectric bimorph energy harvester can be described in the following steps:
Mechanical Deformation: The energy harvester is exposed to mechanical vibrations or deformations in its environment. These vibrations can come from various sources, such as ambient vibrations, machinery, human movement, or other forms of mechanical energy.
Bending and Strain: As the mechanical vibrations or deformations act on the bimorph structure, it undergoes bending and strain. One side of the bimorph experiences compression while the other side experiences tension, causing the piezoelectric materials to deform.
Piezoelectric Effect: The deformation of the piezoelectric materials generates an electric charge imbalance across their surfaces due to the piezoelectric effect. This charge imbalance results in the accumulation of positive and negative charges on opposite sides of the bimorph.
Electric Potential Difference: The accumulated electric charges create a potential difference (voltage) between the two sides of the bimorph. This potential difference is proportional to the applied mechanical stress or strain and can be harnessed as electrical energy.
Harvesting Circuit: The potential difference generated by the piezoelectric bimorph is then connected to an electrical harvesting circuit. This circuit typically includes components such as diodes, capacitors, and resistors. The diodes ensure that the generated voltage is rectified and flows in a single direction, while the capacitors store the harvested electrical energy.
Energy Storage or Usage: The harvested electrical energy can be stored in batteries or supercapacitors for later use or directly utilized to power electronic devices or sensors in the vicinity.
It's important to note that the efficiency of a piezoelectric bimorph energy harvester depends on various factors, including the material properties of the piezoelectric materials, the design of the bimorph structure, the frequency and amplitude of the mechanical vibrations, and the impedance matching between the harvester and the harvesting circuit. Proper optimization of these parameters is essential to maximize the energy conversion efficiency of the device.