A sensor apparatus, the sensor apparatus comprising: a bracket having a cylindrical structure with two open ends; a first leading wire, the first leading wire disposed on a first polar plate, the first polar plate arranged to store charge and disposed at a first end of the bracket, and the first leading wire diametrically connected across the first end of the bracket, wherein the first polar plate and the first leading wire form a first electrode of a capacitor; a support frame hinged to a second end of the bracket by a rotating shaft, wherein the rotating shaft is disposed between a first end of the support frame and a second end of the support frame; a second leading wire, the second leading wire disposed on a second polar plate, the second polar plate arranged to store charge and disposed at the second end of the support frame, the second leading wire connected between the first end of the support frame and an internal side of the bracket, wherein the second polar plate and the second leading wire form a second electrode of the capacitor; a first contact portion at the second end of the bracket, the first contact portion configured to be in rigid contact with a to-be-measured object; and a second contact portion at the first end of the support frame, the second contact portion configured to be in rigid contact with the to-be-measured object; such that in use a stress change of the to-be-measured object drives the rotating shaft to move, and further drives the support frame to move such that the second leading wire also moves with the support frame thereby changing an electrode spacing and an area of overlap between the first electrode and the second electrode of the capacitor, and causing a capacitance value change of the capacitor. a bracket having a cylindrical structure with two open ends; a first leading wire, the first leading wire disposed on a first polar plate, the first polar plate arranged to store charge and disposed at a first end of the bracket, and the first leading wire diametrically connected across the first end of the bracket, wherein the first polar plate and the first leading wire form a first electrode of a capacitor; a support frame hinged to a second end of the bracket by a rotating shaft, wherein the rotating shaft is disposed between a first end of the support frame and a second end of the support frame; a second leading wire, the second leading wire disposed on a second polar plate, the second polar plate arranged to store charge and disposed at the second end of the support frame, the second leading wire connected between the first end of the support frame and an internal side of the bracket, wherein the second polar plate and the second leading wire form a second electrode of the capacitor; a first contact portion at the second end of the bracket, the first contact portion configured to be in rigid contact with a to-be-measured object; and a second contact portion at the first end of the support frame, the second contact portion configured to be in rigid contact with the to-be-measured object; such that in use a stress change of the to-be-measured object drives the rotating shaft to move, and further drives the support frame to move such that the second leading wire also moves with the support frame thereby changing an electrode spacing and an area of overlap between the first electrode and the second electrode of the capacitor, and causing a capacitance value change of the capacitor.