**2.2.3 Skin**

The skin is the most important factor to make human like hand, because skin is the part which is shown intuitively. There are some considerations for an artificial skin. These are texture, color and details like wrinkle, so it needs not only technology but also arts. The silicon composite was selected as an artificial skin, because it is the closest material to human skin than any other materials and it is easy to handle. The artificial skin also used 3D data as a reference, but there are more steps to use. To make a silicon complex skin, the mold is needed, because the process of making silicon complex is like one of making plasters. The 3D data was used to make mock up model. To make exactly same model to original model, RP (Rapid prototype) was used to make mock up model. After making mock up, mold was made by using this mock up model, and a silicon complex skin can be made. The artificial skin which is made by silicon complex is very similar to human skin, but to raise the similarity, make up was taken in final step. Though the mechanical part was made by consideration of shape, there are gaps between parts and skin. This gaps can make wrinkles when the finger bended. To solve this problem, art clay was attached to gaps between mechanical parts and skin. Fig. 4 shows a silicon composite artificial skin for hand.

Fig. 4. A silicon composite artificial skin for an android robot hand.
