Miniature stiffness tunable device with magnetorheological fluid

This study demonstrates new liquid encapsulation method based on adhesive force between liquid and solid. Various liquid encapsulation methods have been proposed. However, these method have limitations. For example, the structure that encapsulates liquid in palyrene membrane are too fragile and not suitable for actuators. Bonding methods can applicable to only two dimensional structures. We developed a liquid encapsulation method with only two process in miniature structure. We utilized magnetorheological (MR) fluid that reacted to an external magnetic field as encapsulated liquid. We investigated the relation between the size and various fabrication factors. We also investigated the relation between the applied magnetic field and the resulting resistive force for application. The results indicated that resistive force increased from 6.2 mN to 9 mN by applying the magnetic field of 400 mT. The structure can be applicable to tactile display that present spatial distribution of stiffness.