Researchers are currently trying to develop materials which could be used to replace damaged or destroyed human muscle tissue. One of the more promising avenues of research involves the use of substances that contract with the application of a small electric current.
Two physicists published an article relating to their work with Substance Q42, a material which contracts with the application of very small electric currents.
The atomic structure of the substance, they report, is designed so that the magnetic fields from each atom maintain a certain distance between adjacent atoms. With the application of an electrical current, the atoms' magnetic fields are dampened slightly, causing them to draw closer together. The extent to which it contracts is dependent upon the strength of the current passing through it, but will at any rate never exceed a 20% reduction in length.
Moreover, the physicists report, Substance Q42 essentially operated like a spring, but one which can compress itself. The force generated by a spring, Fs, is given by the following equation:
Fs = -kx,
where k is the spring of constant in N/m, and x is the distance of compression (or expansion, but that is irrelevant for this example, since Substance Q42 only compresses).
With this in mind, it is possible to calculate the feasibility of using Substance Q42 as a replacement for human muscle tissue. Assume a section of test Substance Q42 is hooked to a scalable electrical source.
The section is 10 cm long at its fully extended state, and 8 cm long when fully compressed due to an electrical current.
If an artificial arm muscle must be capable of doing 8 J work in 0.5 seconds time in order to efficiently substitute for human tissue, what average power must the section of Substance Q42 be capable of?