The main feature of the spring mechanism design was that the whole mechanical system is a paper spring system (Fig. \ref{SpringDesignMechanism}). It was observed that paper spring that was arrange in triangle shape (three-spring mechanism) and rhombus (four-spring mechanism) provide the largest flexibility. In addition, by segmenting the spring mechanical system into different segments will increase the rigidity of the spring mechanical system.
After testing of both systems, it is observed that the flexy finger design has a better rigidity as compared to spring mechanism design. However, the spring mechanism is also being used to provide the second degree of freedom for thumb in both aduction and abduction. The design was subsequently transferred and modified by using Ninjaflex as the material as it is observed that paper did not have the flexibility as predicted. The paper started to wear off and torn after a few bending and loadings by the servomotor. Moreover, the paper mechanism did not go back to its original position and require a 2-wire mechanism instead of a 1-wire mechanism.
With the basic design and materials confirmed, the project proceeds to the next stage of customizing each design to each specific finger based on the physical dimension and movability.