In one example, a sensor is configured to be implanted into a patient's body. The sensor has at least one sensing element, a measurement device in communication with the at least one sensing element, and an internal wireless communicator in communication with the measurement device. The at least one sensing element includes a resistor, and the measurement device includes a capacitor. The measurement device measures a discharge time of the capacitor through the resistor so as to generate a measurement value that is proportional to a value of an anatomical property of the anatomical body, such as strain, that is observed by the sensor. The internal wireless communicator wirelessly communicates the measurement value through skin of the patient to an external wireless communicator situated outside of the patient's body.