The digitization of the mechanical engineering industry requires a large amount of reliable data on the operational state of a machine or mechanical equipment. In almost every machine or mechanical equipment there are standardized machine elements such as screws, bearings and gears in the immediate vicinity of the process. It makes sense to integrate sensor systems for data acquisition and processing for different process-relevant measuring tasks right there, i.e. "in-situ". For example, sensor systems integrated on a gear wheel can provide various information, such as angle of rotation, acceleration, vibrations, local temperatures and more. if necessary. Using e.g. signal processing or AI methods the identification and therefore immediate reporting of incipient damages at an early stage is possible. For this purpose, the German research foundation (DFG) has set up a priority program in which the scientific basis for "sensor-integrating machine elements" (SiMe) and their methodically supported conception and system integration are researched. In this paper the fundamental challenges in the development of energy self-sufficient sensor systems and their potential for the application in machine elements in the individual priority program projects are described and discussed.