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Optical Sensor Assembly on knee Brace for continuous knee monitoring application



Knee joint is an important part of human body. People with poor knee condition generally have limited physical movement, rendering to mental stress and agony. Current technology to support the knee diagnosis and treatment procedures are limited to the use of manual goniometer, x-ray and magnetic resonance imaging (MRI). Alternative devices with continuous measurement capability for knee monitoring are minimum at this time, mainly due to the difficulties to cover the wide angle of the knee flexion. X-ray and MRI technologies are useful to have some insight on the knee problem, but they are not applicable for continuous monitoring. Aside from being expensive for general use of MRI, x-ray on the other hand can cause short-term side effects due to radiation exposure.


The method aimed in this paper is to demonstrate the use of optical sensor integrated with mechanical gear system as a knee monitoring device. A plastic compartment, made by using 3D printer is used to place the sensor and the gear system. The design of the overall device allows direct attachment on a knee brace for easy placement on the knee.


Based on current study, the proposed sensor has a range of motion between 0 deg. to 160 deg., 0.08 deg. resolution as well as support continuous monitoring of the knee.


The sensor performance has been demonstrated for gait motion, ascending and descending stairs, sit-to-stand movement and maximum knee flexion applications.

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The authors wish to thank Universiti Malaysia Pahang (UMP) and Kementerian Pendidikan Malaysia (KPM) for the funding awarded to the author to complete this study under the national grant reference number: FRGS/1/2019/TK04/UMP/02/18 (FRGS) and RDU1901218 (UMP).

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Correspondence to G. M. Salim.

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Future Work

To further validate the sensor’s clinical applicability of the proposed optical based sensor by comparing its results with Vicon system (3D motion analysis). Other than that, to fabricate a smaller and finer mechanical components (gear and rack shaft) using accurate CNC machining to produce a smaller and lighter overall sensor.

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Salim, G.M., Zawawi, M.A. Optical Sensor Assembly on knee Brace for continuous knee monitoring application. J. Med. Biol. Eng. (2022).

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