In the rapidly-developing information society there is an ever-growing demand for information-supplying elements or sensors. The technology to fabricate such sensors has grown in the past few decades from a skilful activity to a mature area of scientific research and technological development. In this process, the use of silicon-based techniques has appeared to be of crucial importance, as it introduced standardized (mass) fabrication techniques, created the possibility of integrated electronics, allowed for new transduction principles, and enabled the realization of micromechanical structures for sensing or actuation. Such micromechanical structures are particularly well-suited to realize complex microsystems that improve the performance of individual sensors. Currently, a variety of sensor areas ranging from optical to magnetic and from micromechanical to (bio)chemical sensors has reached a high level of sophistication. In this MESA monograph the proceedings of the Dutch Sensor Conference, an initiative of the Technology Foundation (STW), held at the University of Twente on March 2-3, 1998, are compiled.