Q. If one made an Eruv Tavshilin, is he obligated to do some Melacha (work) on Friday to avoid a Bracha L’vatala (an unnecessary blessing for the Eruv)?
If a person is hospitalized on Yom Tov does he need to figure out a way to do Melacha to save himself from a Bracha L’vatala?
A. The Eruv Tavshilin’s purpose is to provide the permission to do an usually prohibited work in Yom Tov for Shabbos when needed. It fulfills it’s purpose whether one used it or not, so the bracha recited on it will not normally be an unnecessary blessing.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a