Embedding without disruption: The basic challenge of sensor integration

The basic challenge in embedding sensors in materials is meet simultaneously two conflicting requirements: On the one hand, we want to retrieve sensor data from the material, thus we have to integrate sensors and interconnections. On the other hand, sensors are foreign bodies in the material, which may deteriorate its macroscopic properties. This paper discusses several possibilities to integrate sensors in material avoiding subsequent deterioration of its macroscopic performance. It is our idea to reduce the volume of the sensor to the minimum which is needed to guarantee the function. This approach is called function scale integration. Two examples for material integrated MEMS devices will be discussed in this paper. The first one is a thermoelectric energy harvester, embedded in aluminum during the casting process. The second example is a thin and flexible foil sensor which can monitor the process of polymerization of a compound material. These sensors represent the first step towards function scale integration.