Researchers at the Massachusetts Institute of Technology (MIT) recently designed a photovoltaic-powered sensor that can transmit data and can be used for several years before the battery needs to be replaced. There is no doubt that the importance of the Internet of Things (IoT) has become increasingly prominent with the development of 5G. It uses information sensing devices and networks to connect all things in people's lives and production, and to interact with information, thereby achieving intelligent identification and management. Experts predict that by 2025, the number of IoT devices worldwide (including sensors that collect real-time data about infrastructure and the environment) may increase to 75 billion. However, as it stands, these sensors require frequent battery replacement, which may be a big problem for long-term monitoring. MIT researchers installed thin-film perovskite cells on ordinary radio frequency identification (RFID) tags as "energy harvesters." This battery is known for its potential low cost, flexibility and easy manufacturing, and can power sensors in bright sunlight and darker indoor conditions. In addition, the researchers found that solar energy actually provides a strong power to the sensor, allowing data to be transmitted over longer distances and enabling the integration of multiple sensors onto one RFID tag.In response to this discovery, two papers from MIT's Photovoltaic Laboratory and Auto-ID Lab were published in IEEE Sensors and Advanced Functional Materials respectively. Several professors, postdoctoral fellows, researchers, and students from the two MIT laboratories participated in the research. Integrating two low-cost technologies As society pays more and more attention to issues such as environmental protection, people have also put forward higher requirements for clean energy. In many recent attempts to create self-powered sensors, some researchers have used solar cells as energy sources for IoT devices. However, these studies basically make a smaller version of traditional solar cells instead of using perovskites. Sai Nithin R. Kantareddy, the lead author of one of the papers and a doctoral student at MIT's Auto-ID Laboratory, said: "Traditional unit components can achieve more efficient, durable and powerful performance under certain conditions, but for ubiquitous IoT sensors, traditional methods are actually not feasible." For example, traditional solar cells are very large and relatively expensive to manufacture, and even reducing their size requires a considerable cost.Moreover, they are not flexible and cannot be made transparent, which is necessary for temperature monitoring sensors placed on environments such as windows and car windshields. In fact, traditional solar cells at this stage can only effectively collect energy under strong sunlight, not under low-light conditions indoors.