Miniaturized, integrated sensors and actuators are more and more used in m i c r o s y s t e m applications. In order to promote their use further, specialists must make them more accessible t o system designers. This can be done through behavioral modeling of sensors and actuators. The resulting models can be used in conjunction w i t h models of the associated electronics to simulate a complete microsystem. Additionally, models of t h e non-electrical environment (stimuli, other d e v i c e s ) should be developed too. This paper presents our contribution to solve this modeling and s i m u l a t i o n problem. We propose to use and eventually ex tend existing analog and mixed electronic design t o o l s in such a way that microsystems can be s imulated globally at an early stage of the design.