I wonder if you can recover enough heat from the skin to perform a useful function. This has often been discussed as a means to, say, charge a smartwatch or a cellphone battery. Even if it were possible to draw heat this way, if such a device were to produce a reasonable energy output, I would think the heat transfer from the body could make a person feel cold. This might be useful in the summer but not so much in the winter. I am prepared to be convinced otherwise. I have no doubt, given sufficient time and money, that this can be made to work but I am skeptical about the efficacy and acceptance of the ultimate solution.