Self powered microelectromechanical oscillators are provided for various applications. In one embodiment, the invention relates to a self powered microelectromechanical tagging or sensing system including a microelectromechanical oscillator having a characteristic frequency, the oscillator including a first substrate having a radioactive material configured to emit electrons, and a second substrate, spaced apart from the first substrate by first and second ends supported at spaced locations on the first substrate, where the second substrate includes a flexible material and is configured to collect the electrons emitted from the first substrate, and move toward the first substrate from a default position to an actuated position when a sufficient number of electrons have been collected, where, in the actuated position, collected electrons are transferred from the second substrate to the first substrate, and a circuitry configured to receive, from the oscillator by wireless communication, information indicative of the characteristic frequency of the oscillator.