EXECUTIVE SUMMARY 

The goal of the work presented in this document is to define the best suited sensing principle and fabrication technology for the MEMS sensors within the MEMSCON project. Two components are required: a 1D strain sensor and a 3D accelerometer.

The first part of the document describes the possible measurement principles and fabrication technologies for the accelerometer. The different measurement principles and fabrication technologies are analyzed and the advantages and disadvantages with respect to the MEMSCON project are evaluated. Based on this evaluation and the expertise at MEMSCAP, the basic concept for the 3D MEMSCON accelerometer is developed. A capacitive sensing principle with mechanical elements realized in a surface micromachining technology is selected. The sensor will use independent mechanical elements for each axis. For the in plane sensing, interdigitated comb structures will be used. For the out of plane sensing a pendulum type of element will be realized. The fabrication technology for the three elements is identical; therefore the three elements can be placed on the same chip building a 3D accelerometer.

The second part of this document describes the analysis done for the strain sensor. The different requirements of the end uses and their influences on the choice of principle are given. The requirement that was found to be the most challenging was the combination of a large measurement rang and high accuracy. This requires a very sensitive sensing principle.

Following the requirement, different sensing principles were studied for the strain sensor. Literature research showed the state-of-the-art of each principle and the internal experience of C2V brought the advantage and disadvantage of each principle regarding the fabrication of the sensors. After comparing each sensing principle, it was found that the capacitive sensing principle was the most appropriate because using this principle means that only one ASCI needs to be fabricated for both the accelerometer (other sensor part of the MEMSCON project) and the strain sensor. Moreover, sensor using the capacitive sensing principle exhibit good behavior and the fabrication of such a sensor require only relatively standard MEMS processes.