Like a stretchable antenna structure, i have an arm in my project and i want that arm to expand on command so i was thing what can be done for it ... I want to use chemistry this time so i was thinking following steps: if we chose an exothermic chemical reaction that can produce CO2 having positive ΔG at normal temperature and fill my arm with it. And then make some electric connection within those chemicals so that on providing a potential difference across those terminals (and deciding that potential difference on the basis of equation ΔG=-nEF) such that ΔG becomes negative for that moment and produces CO2 at pressure which will push up the arm. and as soon as the potential difference becomes 0, the spring system will bring the arm back. well this is all what i'm thinking . Will it work ? please help.