Piezoelectric membrane materials exhibiting elevated piezoelectric coefficients and electromechanical coupling coefficients are essential elements in sensors and actuators across various industrial and healthcare domains, including vibration energy harvesting systems, self-sustaining smart structures, wearable biomedical devices, and non-destructive testing applications. Flexible electronics have great application prospects in future wearable and implantable biomedical devices. To fulfill the demands of sensor networks in the Internet of Things (IoT), piezoelectric thin films incorporated onto silicon substrates have garnered significant attention due to their superior electrical characteristics and very inexpensive production costs. Hydrogel-based electronic devices are extensively utilized in wearable sensors due to their bionic structure, human biocompatibility, and electrical stimulus response characteristics. This chapter analyzes the design and strategy of piezoelectric film-based micro-electromechanical systems (MEMS) technology and hydrogel-based piezoelectric devices, and it demonstrates the utilization of hydrogel-based piezoelectric devices in biomedical applications such as health monitoring, tactile sensing, wound healing, energy harvesting, and ultrasonic devices. The remaining challenges and perspectives in this field are mentioned. This chapter discusses various aspects of biomedical devices related to piezoelectric sensors. A comprehensive grasp of piezoelectricity is essential for future advancements and industrial concerns.