Bionic Limbs: Artificial Limbs That Live

  • SumoMe

Sudha Chandran, the veteran dancer and actor, took up a challenge and proved herself. After having her leg amputated as a result of a car accident she tirelessly tried and achieved success in not just a limp-less walk but also on the stage of dance, fulfilling her dream of being a highly acclaimed personality. What aided her was the ‘Jaipur Foot’. The Jaipur foot is the brainchild of Mr. Ram Chander Sharma of Bhagwan Mahaveer Viklang Sahayata Samiti, Jaipur. In 1968, a foot made of vulcanised rubber hinged to a wooden limb was fabricated by him to aid the persons who had lost their legs to landmines and occupational hazards. Thus, in India was born an invention which made life easier for many.

 

The movement of any body part is controlled by the cortex in the brain, aided by the nervous system and the specialized nerve cells called motor neurons. The ‘will’ to move a body part, in a particular way, originates in the cortex in the form of electrical currents, which are conveyed through the neurons to the particular body part in question. The body part then moves as a result of the electrical current getting converted into motion by the contraction and relaxing of the specific muscles of that body part. When a body part becomes numb, the brain becomes insensible to its ability for movements. There occurs a divorce between the functioning of the brain and the body part. Like when the legs become numb, we stumble if we try to walk, because due to lack of blood circulation the nerve endings in that particular part fail to respond to the brain’s command. The legs seem dismembered from our body. An anesthesia shot is similar in effect, which functions by blocking nerve conductions, in which case the sensation of the nerves is not carried to the brain. The same is the case with an artificial limb. Any movement of the attached limb is not perceptible to the brain. It is an alien part attached to the biological self, acclimatizing to which would take time. And if in some cases the psyche is not ready to accept the alien part it becomes a useless stump of metal and wood. However, as seen above in Sudha Chandran’s case, it is also possible to overcome the initial discomfort to lead a normal, pre-amputation life.

 

Keeping up with the pace of the plummeting number of discoveries and inventions in science and technology, experiments to come up with new techniques in the field of the artificial limbs are underway; these aim at advancing the artificial limbs from being a visual appearance to such devices as would enable amputees in leading a normal life with functional limbs. These researches, employing complex processes and specialized chips, are aimed at devising methods which imitate the natural neural control of motor activities in a healthy body. The electrical current issued by the neurons in the cortex are read and transferred to the artificial limb which in turn, acting like muscles would cause the flexing of the artificial limb, in imitation of a natural limb. This interface between an alien body and the human brain is called the Brain-Machine Interface (BMI). BMI is of two types: Invasive BMI and Non-Invasive BMI. In both cases electrodes are used to read the brain’s activity. The difference lies in the fact that a Non-Invasive BMI uses the electrodes without piercing the brain tissues. The electroencephalogram is one of the earliest Non-Invasive BMI devices. While the Non-Invasive BMI is able to read the brain’s activity with respect to the electricity passing through the axons of a clump of neurons, the Invasive BMI is capable of reading the electrical activity of a neuron in isolation. In this case, a very slim electrode placed parallel to the axon of a neuron tracks and reads the electrical activity.

 

This new phenomenon called BMI and the new artificial limb called the bionic limb will give an opportunity to people with damaged or dysfunctional sensory and motor neurons, to use their brain to control artificial body parts and restore lost ability. These bionic limbs are being so fabricated as to have even the feel, besides functionality, of a natural limb. The good news is not only for amputees but also patients of incurable ailments like the motor neuron Alzheimer’s disease. Besides this, the new invention moves outside the paradigm of limb movements to accommodate restoration of communication ability for victims of stroke and other paralytic disorders. This can be achieved by using the method to map and translate thoughts into communicable format using computer programmes, instead of to flex alien parts attached to the body.

 

Science today is advancing at a fast rate to make life more comfortable and worth living. In his attempt to achieve supremacy and self-betterment, man is moving, probably involuntarily, to a scenario where all activities are controlled by the human brain, at the speed of thought. There might, in the far future, be a situation where people would trade their healthy natural limbs for stronger, synergist, pain-enduring and multi-tasking bionic limbs.

 

Deepa Sebastian

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