Table of Contents
Review of Existing Robot Hands
- Claw Grip
- Pneumatic Grippers. See for example SMC where the MHCM2-7S is described - A 2-finger, single acting gripper with a total body length 23mm. The gripper has an opening/closing angle of 20 degrees to –7 degrees and a gripping moment value of 0.017 Newton meters.
- Microhand is a microscopic (several millimeters) manipulator that can be used for surgical operations.
Many robot 'hands' have three 'fingers' so as to reduce cost and simplify control. Industrial one-purpose robots  rarely have fingers at all, instead having the tools directly affixed to them.
At the micro scale (keyhole surgical instruments), specialised tools are the norm too.
Review of Grips in Nature
- Ants ('toothed' legs)
- Many animals use their mouth as the main 'gripper'.
Near Future Robot Hands
The near future general purpose robots will have hands like humans. This is so that they can use a wide range of existing tools without the cost of modifying those tools, and without the inconvenience of having different tools for people and for robots.
In 2006 researchers from AIST have developed a multi-fingered hand for life-sized humanoid robots that is a significant improvement over previous robot hands. It has versatility and dexterity, strength and smoothness approaching a human hand. 
One stepping stone towards Nanotechnology is a robot hand with a span of less than 1cm. This will be used under desktop computer control for delicate micro-engineering work. Only tiny amounts of material will be used in making such a hand, making them very cheap, at least as far as the materials costs go.
- One intriguing concept is robots with fractal-arms. This was investigated by NASA in 1997 
Biotechnology and Human Hands
Once replacement organs can be grown-to-order, estimated circa 2080, there will be many experiements with modified human hands. Surgery to replace a damaged hand will typically involve replacing some muscles and tendons in the arm as well.
Some potential modifications:
- Decorative changes, such as patterns of skin colour, naturally coloured and/or corrugated nails.
- Double jointed fingers for greater flexibility, but reduced strength.
- A second opposable thumb, adjacent to little finger (or instead of), giving a better grip, e.g. for mountaineers holding onto a rope. Pandas have two thumbs on each 'hand' which helps with handling their main food source, bamboo.
- Thicker skin, as on sole of foot, on palm and back of hand, giving better protection against scalds and burns.
- Larger hands, possibly webbed, better suited for swimming.