AUTHOR DETAILS – JATIN KUMAR 

Electricity is very much part & parcel of the biological systems. If we look all around us, we will find astonishing examples of electricity, flowing in the biological system in various forms, like Nerve impulses, those are nothing but electrical impulses which are flowing in your body; the way your heart beats, that is nothing but the flow of electrical impulses which regulates the flow of blood all over your body; the memory acquisition phenomena, it is also an electrical phenomena; the motor actions, the propagation of nerve impulses, the way your muscle responds to some kind of stress/strain, there is a translation of mechanical energy into electrical signals; in the case of touch me not plant (Mimosa pudica), we touch the leaves and it folds, it’s an electrical phenomena; think of the situation in Venus fly trap (carnivorous plant), insect touches some specific part of flower and it closes, it’s another example of electrical phenomena. There are some touch sensors, which senses that impulse and translate them to electrical signals which result into the closing of trap along with the insect. Similarly there are several inanimate objects which exhibit electrical phenomena, like Hornet nest, which have thermoregulatory property & that thermoregulation is driven by the Hornet cell cap which is present there, called thermoelectric membrane; photosynthesis, where solar energy causes the emission of electron & that electron eventually hops through inside the plant cell & leads to the generation of food.

In nature, some organisms have ability to discharge a large amount of electricity from their body. These are Electric fishes, which have fascinated humans for a long time. In the ancient time, Egyptians used the Torpedo (an electric marine ray), as an electrotherapy to treat epilepsy. In Victorian times, guests in the party usually experience the shock of an electric fish. Worldwide, there are hundreds of electric fishes categorized into six broad lineages, which evolved independently, using essentially the same genes and developmental and cellular pathways to make an electric organ and their taxonomic diversity is so great that Darwin himself cited electric fishes as critical examples of convergent evolution.

The electric organs in fishes are probably needed for defence, predation, navigation and communication in the murky environments within the water. All muscle cells have electrical potential; and an easy contraction releases a low amount of voltage, but at least 100 million years ago some fish began to amplify that electrical potential by evolving from muscle cell to another specialized cell called an electrocyte, which is larger in size, organized in sequence and capable of generating much higher voltages. The series alignment of thousands of such electrocytes and the unique polarity of each cell, results into the summation of voltages, much like the batteries in series in a flashlight and an eel/electric knifefish (Electrophorus electricus) body contains millions of such flashlights, working together and firing their electrical discharge simultaneously. These are the few examples of bioelectric processes, occurring in nature that have been exploited or understood from different perspective.

Bioelectricity is a very broad term. The whole body is governed by bioelectrical phenomena & understanding these individual bioelectrical phenomena has profound implication in understanding our whole existence. In biological systems essentially we measure the currents of pico-ampere, nano-ampere, and femto-ampere likewise. In order to measure such current we need a different kind of devices i.e. high impedence devices. Currently with advancement of amplifiers-high end amplifiers we are now able to measure even extremely low electrical potentials in all different forms of life existing in nature.

Understanding of electricity in the biological systems was first reported in 1789 by an Italian physicist Luigi Galvani between nerve and muscles; he observed a flex in a dead frog’s leg when he touched an exposed sciatic nerve with a charged metal scalpel. At that time Galvani believed that the contractions in muscles were due to electrical energy radiating from the animal. However, Allesandro Volta was convinced that the electricity in Galvani’s experiment originated by the presence of dissimilar metals. These interpretations represented the two different aspects of electrical potential in biological systems i.e. the action potential and the electrical potential. These findings provided the basis for current understanding of bioelectrical phenomena in various systems of life forms.

 Medical and biotechnological applications of bioelectrical phenomena

  1. Artificial leaf that mimics the natural leaves and absorbs sunlight to generate hydrogen fuel from water, an advance that may provide a clean and sustainable source of energy for powering eco-friendly automobiles in future.
  2. Different colour dyes of nature are being used to develop dye sensitive solar cells.
  3. Man-machine interface; if a person is blind or the retina is not functioning, is there a way we could implant synthetic or electronic camera infront of the eyes so that the image which is formed in the eyes could be interfaced with the brain. So we totally bypass the sensory mortality because this has been successful in cochlear implant in ears, where a mike is placed into the ear and that mike is being connected to the brain, so whatever you are hearing is bypassing the ear because the eardrum is no more functional. So we bypass everything & interface it with brain.
  4. Latest Biomedical instruments like electroencephalography (EEG), electrocardiography (ECG) and electromyography (EMG) used to measure action potentials from the brain, heart, and muscles respectively.
  5. High end touch biosensors.
  6. Bio-MEMS – biomedical (or biological) microelectromechanical systems.
  7. Biological pacemakers.
  8. Implantable sensors.
  9. By getting these inspirations and learning’s from nature, we may be able to manipulate the physiology of muscles in desired organs or organisms in near future to create electrocytes for generating sources of electrical power in bionic devices within the human body. Bioelectricity is amenable to transfer the cellular signal to the digital circuits which helps in development of high-throughput biosensors that can evaluate the whole body metabolic activities.

 Any electrical phenomenon has a direct link – that this could be used for energy harvesting. More and more we are heading for sustainable energy our biggest hope is to learn from nature, the sustainable route to harvest energy.

References:

  1. Emma Young, Electric Eel–Inspired Devices Could Power Artificial Human Organs, Nature magazine December 15, 2017
  2. Terry Devitt, Scientists find the shocking truth about electric fish, University Of Wisconsin–Madison News, June 26, 2014.
  3. Yong Jeong, Introduction to Bioelectricity
  4. Enderle J (2004) Bioelectric phenomenon. In: Introduction t o biomedical engineering, 2nd edn. Elsevier, Oxford, UK, pp 627–692
  5. Reilly JP (1998) Applied bioelectricity. From e lectrical stimulation to electropathology. Springer, New York, NY.
  6. Patra, Kshirodra Kumar, Bhuskute, Bela D. GopinathChinnakonda S. , Possibly scalable solar hydrogen generation with quasi-artificial leaf approach, Scientific Reports, volume 7, Article number: 6515 (2017).