Let us consider again the four-step quasi-static cycle:

1. The polymer is initially stretched. The operator adds hydrogen ions to the system. The force of contraction increases.
2. The polymers contracts and lifts the weight.
3. The operator removes the same amount of hydrogen ions from the system. The force of contraction decreases.
4. The operator stretches the polymer and restores the initial state.

Note that the operator, as he decreases and then increases the pH of the system (steps 1 and 3), does no NET work - he gains work if the hydrogen ions are transported from a high to a low concentration, e.g. in step 1, and then loses the same amount of work in the backward transport, in step 3. Still, even though the NET work is zero, the operator is involved in work production.

There are isothermal heat engines where the operator is NOT involved in work production. In this video he just switches the capacitor on and off and the water can cyclically lift floating weights, in violation of the second law of thermodynamics:

http://www.youtube.com/watch?v=T6KAH1JpdPg
"Liquid Dielectric Capacitor"

Isothermal heat engines where the operator is not involved in work production can generate perpetual motion. The following system is essentially identical to the capacitor system demonstrated above (in both cases we have water in an electric field):

https://www.youtube.com/watch?v=17UD1goTFhQ
"The Formation of the Floating Water Bridge including electric breakdowns"

Pentcho Valev