Tissue engineering aims to create functional and physiological tissues in vitro. In this seminar, I will first describe a microfabrication technique for engineering 3D microtissues that serve as tissue models to complement conventional 2D cell cultures and animal models. I will give an overview of the use of these models to assess cardiac muscle, skeletal muscle or stromal tissue contractility, as well as to screen the effects of mechanical parameters, drugs or mutations on tissue formation and maturation. I will then present several approaches developed in our team to actuate these engineered tissues, using electrical, mechanical or optogenetic stimulation, in order to gain information on the functional capacities and mechanical properties of the tissue.