# Integration of AI in Self-Powered IoT Sensor Systems
## 5 Self-Powered IoT Sensors Identification and Applications  
One of the biggest challenges of IoT sensors concerns the power source. To prevent this problem, autonomous IoT sensors have been produced, which generate their energy in addition to their primary function of collecting and transmitting data in IoT networks. This category of sensors does not require external power sources, such as traditional batteries or direct electrical power. Instead, autonomous IoT sensors capture energy from the ambient environment and transform it into a source that helps them perform basic functions. The autonomous IoT sensor collects data from the surrounding environment and transmits it to the central system via the network, operating without batteries or other conventional energy sources. These sensors are self-powered by generating energy using elements from the surrounding environment. Ambient energy harvesting technologies classify autonomous IoT sensors into three categories of sensors [149]:  
1. Sensors that utilize mechanical energy, such as movement, vibrations, or pressure. This category includes piezoelectric and triboelectric generators. Piezoelectric sensors generate electrical energy by applying a mechanical force (pressure, vibrations). This category of sensors is discussed in a multitude of specialized papers. For example, [PERSON] et al. [150] describe an instantaneous sensing system based on a piezoelectric generator, providing a solution for energy harvesting and immediate data transmission. [PERSON] et al. [151] propose a self-powered accelerometer based on TENG, including a V-Q-a theoretical model applicable to piezoelectric sensors. [PERSON] et al. [151] make a valuable contribution by providing the mathematical foundation for the operation of self-powered sensors. Another application is presented by [PERSON] et al. [152], where a piezoelectric transducer integrated into a composite structure for self-sensing is analyzed. Sensors that integrate energy harvesting with measurement functionality are described by [PERSON] et al. [153]. This paper presents a sensor based on a piezoelectric cantilever, which collects energy from vibrations and measures acceleration autonomously. The system uses a circuit designed for real-time multiplexing to achieve this objective. [PERSON] et al. [154] present a piezoelectric device that converts motion into electrical signals, with the advantage of a simple structure and high instantaneous power density, making stationary and flexible sensors operate efficiently. Besides purely piezoelectric solutions, some studies explore hybrid combinations [155]. For example, [PERSON] et al. [156] propose a flexible epidermal sensor based on the hybridization of piezoelectric and triboelectric effects. The device is designed to be biocompatible with the skin. Another important aspect of piezoelectric sensors is their stability under variable conditions, as demonstrated by [PERSON] et al. [157], which presents a flexible piezoelectric sensor with self-calibration for temperature variations. The sensor contains a system that automatically adjusts the output based on temperature. The piezoelectric energy harvester's (PEH) performance is detailed by [PERSON] et al. [158], demonstrating that these devices can be used as an autonomous power source for wireless sensors. [PERSON] et al. [159] introduce a hybrid piezoelectric-triboelectric sensor created to recognize motor tics. It can detect involuntary movements of the human body. Due to their ability to generate energy using the surrounding environment and provide signals using this self-generated energy source, these piezoelectric sensors become stand-alone devices in the IoT ecosystem. TENG sensors represent one of the most studied technologies for developing self-powered IoT systems. They can convert ambient mechanical energy (vibrations, movement, friction) into electrical energy.