SUMMARYIn this paper, we will highlight the current research which employs the topology optimization to ÿnd the optimal conÿguration of various smart structures and microstructures, speciÿcally, pressure actuated compliant mechanisms, extensional transducers, and porous material microstructures with unusual thermoelastic properties. These examples demonstrate that the topology optimization problem involving multiple physics domain is a viable direction for future research, in particular, for sensor and actuator design.