A review on lead-free piezoelectric ceramic sensors for sustainable and intelligent applications

Lead zirconate titanate (PZT) has long been regarded as the gold standard material for piezoelectric sensorsowing to its outstanding piezoelectric performance (d33 = 500–600 pC/N) and well-established industrial scalability.However, its environmental toxicity, limited mechanical flexibility, and instability under extreme conditionsmake it less suitable for wearable electronics, biomedical implants, and high-temperature sensing. Theselimitations have spurred intensive efforts to develop lead-free ceramic piezoelectric materials as more sustainableand versatile alternatives. Recent advancements in this field highlight the increasing potential of lead-free systemsto rival or even surpass conventional PZT-based devices. This review systematically explores the latestprogress in lead-free piezoelectric materials, focusing on two major directions: the formulation of alternativecompositions such as potassium sodium niobate (KNN) and bismuth sodium titanate (BNT) that aim to achievecomparable performance metrics, and the development of intelligent sensing systems that offer enhancedsensitivity, broader operational temperature ranges, and mechanical adaptability. Rather than focusing solely onreplacing toxic components, this review proposes a multidimensional evaluation framework that considerspiezoelectric coefficients, dielectric properties, and mechanical compliance as equally critical parameters.Moreover, the integration of artificial intelligence (AI) is discussed as an emerging tool to accelerate the discoveryand optimization of high-performance lead-free compounds. Looking ahead, the field is anticipated tomove toward the realization of intelligent, flexible, and multifunctional sensing platforms for use in self-poweredsystems, harsh environments, and advanced energy harvesting technologies, signifying a crucial shift towardsustainable piezoelectric device innovation. Fil: Zheng, Kai. RWTH Aachen University; Alemania Fil: Xie, Ning. University of Jinan; China