This paper reports a novel way to detect the resonant frequency of an electro-thermally actuated cantilever sensor that we have previously reported, in order to perform mass detection by resonant frequency shift detection. The device is based on monitoring the rupture of a clamped cantilever structure due to mass changes. Thus the device can only be used once and is best suited for qualitative mass detection. At the same time, the resonant frequency of the device can be tuned by the input signal power. This allows scanning power instead of frequency, and simplifies device operation and accompanying electronics.