## 1 Introduction  
The advancement of wearable and implantable devices has facilitated the conversion of diverse physiological signals within the human body into unified electrical signals. This transformation is accomplished via the reading of distinct bioelectronic interfaces. Depending on the nature of the signals to be detected, sensors employ different sensing principles. For instance, there exist mechanical signals (such as blood pressure signals, muscle contraction signals, respiratory signals), chemical signals (glucose signals, dopamine signals, lactate signals, oxygen signals), and bioelectrical signals (electrocardiogram signals, electromyogram signals, electroencephalogram signals), among others. These signals are converted into standardized electrical signals through various sensor interfaces and subsequently collected for storage or transmission. Thereafter, they are uploaded to a data center for analysis. This analysis is of paramount importance for discerning human physiological phenomena. Analyzing physiological signals contributes to a deeper understanding of the human body. Bio-implantable devices exhibit a wide range of application scenarios, encompassing daily monitoring, disease diagnosis, postoperative recovery, and so forth. In recent years, there has been a continuous upsurge in discussions regarding implantable devices, and the enthusiasm for research has remained robust. Researchers have developed implantable sensors with diverse principles and structures. These sensors are capable of continuously monitoring the target signal, featuring a compact size, portability, minimal interference with daily life, extremely low energy consumption, and long-term operation. However, the development of these devices encounters numerous challenges. Firstly, there are biocompatibility concerns. It is essential to utilize materials with excellent biocompatibility and minimize inflammatory responses. Secondly, issues related to the secure collection and transmission of data exist. Ensuring the accuracy and privacy of data is of utmost importance. Thirdly, power supply problems need to be addressed. This necessitates the development of reliable long-term power supply solutions or self-power supply technologies. Additionally, challenges regarding the long-term stability and reliability of the devices must be considered. Published reviews on implanted devices also delve into these matters. For instance, implanted devices are influenced by motion artifacts. Decisions need to be made regarding the flexibility, durability, and human adaptability of biomaterials, along with the performance requirements of implanted batteries and their potential effects on the human body. Moreover, discussions have also taken place regarding concerns about the privacy and information security of medical data in the era of the Internet of Things. As the nucleus of the entire system, the sensing unit assumes a pivotal role. To effectively monitor diverse signals, a meticulous selection of the most appropriate sensing mechanism is imperative. For instance, when it comes to monitoring internal pressure signals within the human body, resistive, capacitive, LC resonant, and piezoelectric sensors can be employed, each of which exhibits distinct advantages and limitations. Resistive pressure sensors can be fabricated to a remarkably small size, rendering them highly conducive for implantation in the human body. Nevertheless, their resistance demonstrates relatively high sensitivity to temperature variations, thereby necessitating temperature compensation. Moreover, their sensitivity is generally low [1]. Capacitive sensors feature higher sensitivity and are well-suited for low-pressure monitoring. However, they typically occupy a relatively large area and are susceptible to parasitic capacitance. LC resonant sensors obviate the need for wired connections and are amenable to miniaturization.