In minimally invasive surgery (MIS) the aspect of miniaturization is getting more and more demanding. On the other hand, it is also important to assure high stability and large actuation forces at the end effector. Here we present the design and the development of a 1 degree of freedom (DOF) rotational joint, which combines a foldable mechanism and a fluidic actuation system for obtaining force magnification within a slender structure (diameter = 5 mm). The foldable mechanism is composed of identical rigid elements connected each other, which sequentially move away from the joint's axis and ensure an output torque of 0.5 Nm.