On the Notion of a Mechanical Battery

We present an electrostatic transducer in which voltage remains constant while charge is stored or extracted from the device. We achieve this by designing a nonlinear mechanical spring, which exactly counteracts the nonlinearity associated with electrostatic attraction forces. In essence, the new device responds like a rechargeable battery, only that here we store electric energy in elastic deformation, whereas in common batteries, electric energy is stored as chemical potential. The capacitance of the presented test devices is currently too small to be practical, and we are not, by any means, suggesting that this transducer can replace chemical rechargeable batteries. Nevertheless, some necessary steps toward constructing a more viable device with larger energy density are discussed.