This wheelchair can make life easier for tetraplegics

COIMBATORE:

Tetraplegics

may no longer have to depend on attenders to move, if the clinical trials of a

wheelchair

that operates on muscle movement is a success. The wheelchair, developed by the

PSG Group of Institutions

, aims to provide low-cost and

self-reliant locomotory assistance

for people with movement disabilities.

The

wheelchair detects muscle movements

through biosensors and the signals instruct it to move in a particular direction. “Muscle movements generate muscle potential, which are detected by bio-compatible surface sensors. These signals are then sent to the microcontroller, which instructs the wheelchair to move,” said C Lakshmi Deepika, co-ordinator of the industry-institute partnership cell at PSG College of Technology.

“While tetraplegic people cannot move their upper and lower limbs, they can move their shoulders,” said the professor and head of physical medicine and rehabilitation at the PSG Institute of Medical Sciences and Research, Dr V Ramamoorthy. “I gave them the feedback that we received from our patients, who were using joystick-operated wheelchairs. After some research, we realised that we could use muscle movement to trigger the movement of the wheelchair,” he told TOI.

Lakshmi Deepika, along with an assistant professor from the biomedical engineering department at PSG College of Technology N Subashini, recorded the muscle movements of 10 students on campus. “While we knew the muscle movement could trigger the movement of the wheelchair, we had to identify specific muscle movements and detect their patterns,” said a senior physiotherapist at PSGIMS&R, A Parthiban. “After compiling a set of muscle movements, we realised that we could use the movement of the upper trapezius on the left and right shoulders and the movement of the forehead and eyebrow muscles,” he added.

Each muscle potential develops a specific pattern on electromyography (EMG). “Based on the pattern, the microcontroller detects the source of the muscle and moves in the respective direction,” said Lakshmi Deepika. This works well for the forward and backward movement. But, for turning to left and right was a challenge as the muscle potential from both left and right shoulders developed similar patterns.

“To rectify this, we separated the circuits for the sensors on the left and right shoulder,” said Parthiban.

The wheelchair is also fitted with ultrasound sensors that detects obstacles. “It will stop 1 metre ahead of an obstacle. At the same time, it also has vision sensors that will detect people behind. Upon detection of people, the wheelchair will sound a buzzer asking people to move away from the path,” said Subashini.

Besides operating it with muscle movement, the wheelchair can also be remotely controlled. The designers have developed an Android application, which can control the wheelchair through Bluetooth. “The Bluetooth range is 100m in the prototype, but it can be increased,” said Subashini, adding that the life of the wheelchair is five years.

The project was funded by the department of science and technology, Government of India. “We received Rs 35lakh and it took three years for us to develop the prototype. STEPS Knowledge Service Pvt Ltd, a Coimbatore-based company, has offered to manufacture the wheel-chair,” said Lakshmi Deepika, adding that the estimated cost of a wheelchair is about Rs 60,000.

The team has been granted ethical committee permission to carry out clinical trials. “We will conduct trails on 20-30 patients and will obtain their feedback. Based on the feedback, we will make changes, if needed. The clinical trial will take about three months,” said Dr Ramamoorthy. Meanwhile, the team is also planning to apply for a patent.