Advances in biodegradable piezoelectrics for medical implants

Piezoelectric devices integrated into physiological systems can be used effectively for biomedical applications such as sensing biological forces, self-powering biomedical devices, stimulating tissue regeneration and healing, and diagnosing medical problems. The limitation of current well-established implantable piezoelectric medical devices is that most of them are non-degradable and require extra removal surgery. Biodegradable piezoelectric implants can avoid the above dilemma by degrading inside the body after fulfilling their service life, and therefore are promising to become the next-generation of biomedical implants. Herein, we firstly systematically review the recent developments in biodegradable piezoelectric materials, including bio-polymers, synthetic polymers, and degradable piezoelectric inorganic materials and their composites. The associated material synthesis methods and device fabrication techniques are summarized. Then, we overview the cutting-edge strategies to realize high-performance biodegradable piezoelectric materials and devices. Subsequently, we discuss the encouraging biomedical applications of biodegradable piezoelectric implants, including biosensing, energy harvesting, tissue engineering, and disease diagnosis and treatment. Finally, future research directions, following the clarification of challenges in mass-market applications are proposed. This article comprehensively reviews biodegradable piezoelectrics from material optimization strategies to device applications, with a focus on the enormous potential of biodegradable transient piezoelectric medical implants.