Fiber Bragg Grating Goniometer for Joint Angle Measurement

Goniometers are extensively used in the medical field, in order to assess the range of angular motion of a joint, especially for therapeutic assessment during physiotherapy. This paper reports a novel device for the dynamic measurement of angular motion of joints using a fiber Bragg grating (FBG) senor. The fiber Bragg grating goniometer (FBGG) is proposed, essentially converts the rotational motion of a joint into strain variation on a cantilever, which is acquired by the FBG sensor bonded over it. The FBGG developed has the capability of measuring joint angles in the range of 0°-200° with a resolution of 0.06°. The FBGG developed has been put to use in the measurement of angular motion of elbow joint along with ankle joint. The angular measurements obtained from the FBGG are validated against the angular measurements from the Polhemus liberty sensor. It is observed that the angular motions acquired from both the methodologies are in good agreement with each other, which proves the usefulness of the FBGG developed. Also, with the inherent advantages of the FBG sensor, the FBGG developed provides an efficient means of evaluation of angular motion of joint, which may be utilized as a platform sensor methodology for angular measurement of various other joints in the human body.