The thing you wish for already exists, Nitinol wires, otherwise known as "muscle wire". From the following link:
"Muscle Wire" is the perfect name for this product because it can be described exactly as it sounds: It is a unique type of wire that acts like the muscles in our bodies. Muscle Wire is an extremely thin wire made from Nitinol (a nickel-titanium alloy) that is known for its ability to contract when an electric current is applied.
Although thin and lightweight, one of the most amazing things about Muscle Wire is that they can lift many times their weight and are able to do 100 times more work per cycle than the human muscle. This material is easy to use, small in size, operates silently, has a high strength-to-weight ratio, and is easily activated using AC or DC power. This technology is ideal where mechanics require minimization, such as electronic textiles projects, robotics or nano-applications.
Either run current through or place these wires in hot water, and they can contract by 5%, and then expand to its full length again once cooled down, or when disconnected from the power source.
You can use those as a core, then pad them out with a gel or some other material (perhaps even wrapping each wire in a tube) to make the muscles feel human to the touch through the android's skin.