A device for converting the kinetic energy of molecules into useful work includes an actuator configured to move within a fluid or gas due to collisions with the molecules of the fluid or gas. The actuator has dimensions that subject it to the Brownian motion of the surrounding molecules. The actuator utilizes objects having multiple surfaces where the different surfaces result in differing coefficients of restitution. The Brownian motion of surrounding molecules produce molecular impacts with the surfaces. Each surface then experiences relative differences in transferred energy from the kinetic collisions. The sum effect of the collisions produces net velocity in a desired direction. The controlled motion can be utilized in a variety of manners to perform work, such as generating electricity or transporting materials.