In a sub-millimeter scale, the conventional mechanical systems including the rigid linkage mechanism can be hardly applied due to limitations on efficiency and manufacturability. Especially, the energy loss caused by friction force over Newtonian force deteriorates energy efficiency of the mechanical systems. To increase efficiency and simplicity of the small-scale mechanical systems, a compliant mechanism is one of the candidates replacing conventional linkage mechanisms. Here, we introduce two types of compliant mechanism-based monolithic structures which are the so-called bistable parallelogram linear stage (BPS) and origami-based deformable morphing structure. These structures are fabricated by a simple manufacturing process and designed by a simplified compliant mechanism and kinematic model. For measuring quantitative performances of structures, we perform experimental studies in terms of energy efficiency and adjustable shape deformation. By using these characteristics, monolithic structures are applied to a variety of device types including an actuator for the wearable AR glasses and body shell of vehicle. In addition, we show that devices equipped with monolithic structure can overcome engineering problems such as the energy efficiency of wearable devices which can be hardly solved by conventional mechanical systems and the mechanical stiffness of morphing structures which are fabricated by elastomeric materials.
