A fiber Bragg Grating-based instrumented glove to measure finger flexure for use in post-stroke rehabilitation
Dr. Arup Lal Chakraborty
Associate Professor, Electrical Engineering
Indian Institute of Technology
Gandhinagar, Gujarat, India
Stroke has emerged as the second most common cause of death large number of deaths worldwide . The annual incidence rate of stroke in India and its neighbouring countries is much higher than in developed countries. A large fraction of those afflicted are left with prominent residual spasticity that drastically reduces the quality of life. Rehabilitation programmes involve tedious exercises and assessment of recovery is largely subjective. Fiber Bragg grating (FBG) sensors are attractive for such applications because they are highly sensitive to strain and their small form factor makes them easy to integrate in assistive or diagnostic devices. This paper outlines the development of an FBG-based instrumented glove  that can simultaneously measure the bend angle of ten finger joint angles. The sensing unit consists of an FBG that is very sensitive to axial strain induced by the flexing of fingers. The spectral shift of the reflection spectrum of the FBG varies linearly with the joint rotation angle. The glove measures ten joint angles (five metacarpophalangeal (MCP) joints, one interphalangeal joint (IP), and four proximal interphalangeal (PIP) joints) of the human hand simultaneously at a rate of 250 Hz. The instrumented glove offers a very high angular resolution of 0.1° with a very high sensitivity of 18.45 pm/°. The results are validated using a pre-calibrated inertial measurement unit (IMU) sensor. The sensor showed excellent repeatability with a maximum standard deviation of 0.30° and 0.79° on a mechanical setup and the human hand, respectively. The glove has much better resolution and dynamic performance up to a rotation speed of 80°/s compared to IMUs that are commonly used in angle measurement. These results demonstrate that our sensor is a strong potential candidate for the development of high-accuracy instrumented gloves that could be used to for real-time monitoring of rehabilitation exercises and contribute to quantitative assessment of the recovery process. Virtual reality (VR) based exercises have emerged as a useful tool in the rehabilitation of stroke survivors. Unlike conventional techniques, immersive and interactive VR interventions incentivize tasks recommended in therapy. Input systems such as instrumented gloves used in VR systems must be accurate, highly repeatable, and have very low latency to make the VR environment immersive. A virtual hand was also deployed on an Android tablet and was controlled by Raspberry Pi-based portable system over a wireless link. A suite of diverse task-specific games is currently under development. The efficacy of virtual rehabilitation will be tested in future.
Dr Arup Lal Chakraborty is currently an associate professor in the Electrical Engineering discipline at the Indian Institute of Technology Gandhinagar (IITGN), India. He leads the Photonics Sensors Lab that has a diverse set of interests such as industrial process monitoring and safety, microbiological and nano-bio-sensing applications, environmental monitoring and biomedical sensing. These activities are heavily inter-disciplinary and use near-infrared and mid-infrared tunable diode laser spectroscopy techniques. Prior to joining IIT Gandhinagar he worked as a Research Assistant in the Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow during 2007-2010 and obtained his PhD from there in 2010 for work on devising wavelength modulation spectroscopy schemes to achieve calibration-free measurements of gas concentration and pressure for industrial applications. He has worked on distributed optical fiber sensing as a Scientific Officer at the Raja Ramanna Centre for Advanced Technology (RRCAT), Department of Atomic Energy, India during the period 2001-2007. He holds a Bachelor of Technology degree in electronics and communications from the University of Kalyani, West Bengal, India. He is a Senior Member of the IEEE, member of the OSA and the OSI. He serves the research community as reviewer of journals of the OSA and IEEE and as member of the technical programme committee of photonics conferences. He has also held several administrative positions in IITGN including Academic Coordinator of the EE discipline and Member of the Academic Senate of IITGN.