Although the piezoelectric constants of organic biodegradable materials are often much smaller compared with non-degradable piezoelectric materials, various strategies have been proposed which could greatly promote piezoelectric response by orders of magnitude, enabling practical therapeutic or diagnostic functions for biomedicine. Materials candidates include synthetic biodegradable polymers (e.g., poly(L-lactic acid), PLLA), protein-based polymers (e.g., gelatin), polysaccharides (e.g., chitosan) and amino acids. By contrast, biodegradable organic piezoelectric materials are attracting great interest due to their desirable biocompatibility and biodegradability that could eliminate retrieval surgeries. Although biotoxicity could be controlled by encapsulation, potential leakage of hazardous constituents still exists, and the non-degradable components could result in unnecessary materials retention associated with infection risks and dilemma of materials retraction. Although conventional piezoelectric materials such as zinc oxide (ZnO), lead zirconate titanate (Pb(Zr xTi 1-x)O 3, PZT), barium titanate (BaTiO 3, BTO), lithium niobate (LiNbO 3, LN), potassium sodium niobate ((K, Na)NbO 3, KNN), polyvinylidene fluoride (PVDF) and its copolymers have demonstrated excellent piezoelectric properties, the presence of toxic or non-biodegradable constituents poses great challenges for use as biomedical implants. These properties help us to choose the best piezoelectric material for our application.Piezoelectrics represent a category of materials that generate electrical charges in response to mechanical stress and vice versa, and have been extensively explored for power devices, transducers, pressure sensors, etc. Low dielectric loss is important for materials used in off-resonance frequency applications accounting for low heat generation.īased on these physical, material, electromechanical properties we can easily distinguish between piezoelectric materials.Materials with high electromechanical coupling factor and high dielectric permittivity are best as transducers.Materials with large piezoelectric strain coefficient, large non-hysteretic strain levels are best for an actuator.Higher the magnitude of these parameters best is the material for the application. Three parameters to be considered for selecting piezoelectric materials for applications working under mechanical resonance are the mechanical quality factor, electromechanical coupling factor, and dielectric constant.Due to the larger electromechanical coupling coefficient, PZT is used in an application where mechanical stress has to be converted to electrical energy.Piezoelectric voltage coefficient of PVDF makes is a better material for sensor applications.Shape change of ceramic-based materials is more than that of polymer-based materials when the same amount of voltage is applied.Polymers have low piezoelectric constant compared to ceramics.In solid materials Z = √ρ.√ϲ where ρ is the density and ϲ is the elastic stiffness of the material. This parameter evaluates the acoustic energy transfer between two materials. This parameter characterizes the sharpness of the electromechanical resonance system. ![]() G defines the relation between the external stress X and induced electric field E as E = g.X. K2 = (Stored electrical energy / Input mechanical energy)ĭescribes the relation of magnitude of induced strain x to the electric field E as x = d.E. K2 = (Stored mechanical energy / Input electrical energy) or ![]() The five important merits of piezoelectric areġ. There are a few factors to be considered while choosing piezoelectric materials. The material that could easily meet our requirement can be considered the best. Piezoelectric materials are chosen based on the requirement of our applications. Which is the Best Piezoelectric Material? These materials are especially used for underwater sonar and medical diagnostic ultrasonic transducer applications.įor bulk acoustic and surface acoustic wave devices thin films of ZnO are widely used because of there large piezoelectric coupling.High coupling factor, low acoustic impedance, mechanical flexibility characterizes these materials.Piezoelectric composites made up of piezoelectric ceramic and polymer phases form excellent piezoelectric materials.These materials are highly-opted for directional microphones and ultrasonic hydrophones.Broad resonance bandwidth due to low QM.These materials have good acoustic impedance matching with water or human body due to there light weight and soft elasticity.Large g constant which makes them a good choice as sensors. ![]() Small piezoelectric d constant which makes them a good choice for the actuator.
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