A micro device includes a substrate and a structure configured to bind to an object or a material, or not to bind to an object or material. The structure has a roughness based on a roughness of the object or material. For example, a microarray includes a substrate and a well positioned in the substrate and configured to bind to a type of bead. The well has a roughness based on a roughness of the type of bead to which the well is configured to bind. The roughness of the well is controlled by controlling a position and number of striations in the side of the well. In another example, a moveable component of a micro device may have a roughness different from a roughness of an adjacent component, to reduce the likelihood of the moveable component sticking to the adjacent component.