A rotary encoder includes an electret unit, an electrostatic field sensor, and a controller. The electret unit generates an electrostatic field. The electrostatic field sensor is disposed proximate to the electret unit to sense a modulation of the electrostatic field that varies with rotation of one or more rotary components of the rotary encoder about a rotation axis of the rotary encoder. The controller is electrically coupled to the electrostatic field sensor to track activations of the electrostatic field sensor as the one or more rotary components rotate. The controller is configured to digitally encode a rotational position of the one or more rotary components based upon the activations.