Micro Robots? Enter the Micromuscle!

Now this video is a must see! The size of these little miniature machines is quite amazing. Check out their website here for more info.

(via Micromuscle's website)
MICROMUSCLE EAP technology

Using MICROMUSCLE EAP technology a wide variety of small moving components can be constructed. The possibility to create moving structures and exert force enables new functionality for medical devices and other life science products.

Electroactive polymers
Electroactive polymers are an emerging class of materials with many new revolutionary properties. One of the main advantages of electroactive polymers is the possibility to electrically control and fine-tune their behaviour and properties.
The electroactive polymers used by Micromuscle AB are characterized by their ability to swell and contract when a small voltage is applied. The mechanism behind this is based on electrochemistry. Swelling is caused by ions and water entering the polymer. When the voltage is removed or reversed, the polymer contracts and resumes its original shape.