The artificial muscle

The android will not exist without artificial muscles. Currently robots have a rather mechanical approach, however, the artificial muscle exists and is effective.

Electroactive polymer: A muscle for surgery

There are plans to use artificial muscles to compensate for disabilities, and the same technology should be functional for robots with a mixed format as the form of exoskeleton to reduce the effort of physical force or leverage.
The Archives of Facial Plastic Surgery describe a method which is a combination of silicon and electrodes to complement biological deficient muscles.
This process called EPAM (electroactive polymer Artificial Muscle) contracts or relaxes the muscles in silicon based on the voltage applied.

Aerogel

This method takes the form of leaf Aerogel composed of carbon nanotubes, ultra light and flexible as rubber and that can relax up to ten times its length. It can withstand temperatures as low as -200 ° or as high as 1500 °!

Very effective, it can contract to 1000 times faster than a biological muscle to 30,000 times per second. According to the electric voltage applied to this material, it contracts or relaxes, as do our muscles.

This material currently lacks strength to equip robots while electroactive polymers are stronger than human muscles.

Reference:

UT Dallas Alan G. MacDiarmid NanoTech Institute.

The muscle in fibers of carbon nanotubes

This new material allows flexibility 1000 times greater than the achievements of polymer. It works the same way as natural muscles, reacting to the stimulation of an electric current.
It is more flexible than rubber and 100 times stronger than human muscle.

The applications are numerous, but the most important are the creation of prosthetics and robotics, finally with something closer to and even better than what nature provides.

Source.