 Welcome back to the NPTEL lectures on Bioelectricity. So, in the last class I introduced to the curriculum what I am going to follow. And I talked to you about the five modules under which this course we dealt with and I also highlighted the fact that each of the modules will be stand alone. So, you really can pick up any module and go through it. So, today what we will do is I will give you a graphical outline of the way the course will progress. So, that will kind of give you an idea where everything fits in because whenever we do a course kind of we lose track like what is the central theme how this whole course is being structured. And especially in a field like bioelectricity which is so diverse from inanimate object to animate object the insect world the world of plants and everything. So, where this all these things kind of converge where really why we devote time. So, today's class will be kind of giving you an overall outline the flow diagram how we are going to progress of course your five modules will remain there those are the five modules we are going to follow, but all those five module can be put under one graphical representation and that graphical representation is extremely essential for you people to kind of appreciate or the integral theme or I should say the central theme behind this whole exercise of 40 lectures where kind of you know you should be able to correlate each and every component of nature. And either you can go on a very fundamental research fundamental studies about it or based on the fundamental findings you can think of how this could be used for different kind of applications like biosensors or you know prosthetic devices or bioenergy plethora of application all over the place ok. So, the way I am going to put the graphical representation just give let me give you a verbal idea about it. So, first of all it will be in a in a tabular fashion will depicted. So, in the left most column we will talk about the system which will be studying it could be an inanimate system it could be insect system it could be the systems of animals it could be a plant system. Then we will talk about the examples under those headings. Then we will talk about the exact physiology or the exact bioelectrical aspect we are going to study in that aspect and what are the techniques which involved in those kind of a study and result of those studies where we can take it ok. So, overall starting from the basic identifying the system characterize the system understanding the mechanism system and the tools employed in the system and last, but not the least is where we can take it from there. So, let me start with slowly drawing the chart with you at every quarter of a stop and I will give you my opinion on it and let us get the whole graphical sketch of the whole course. So, coming back this is where we are bioelectricity this is lecture 2 and the title of the this class will be graphical representation sorry sorry graphical representation of the divers bioelectrical events implications. So, to start off with as I told you so will be the system identification that will be our first system identification this is the first system after the system identification we will move on to bioelectrical phenomena of that system. Next we will talk about the measurement techniques how we are you know measurement techniques then we will talk about the advance applications I expect you people to kind of keep this so what I expect is that I want this to be act as a guiding principle or should be part of your brain map. So, whatsoever in the next rest of the classes what I will be teaching rest of the course you should always try to correlate it with where exactly all those small pieces of information or puzzles are fitting. So, at the end of it you should have a very holistic picture of nature how nature is surrounded or pretty much bioelectrical phenomena is should say integral part of the evolution of nature itself and whatsoever we study in basic physics they are all over the place in biology all over the place it is just we have to identify the system and kind of you know quantify the system and establish a link with the existing laws of nature which have been governed in physical world. So, coming back to the first system identification part this is our system one. So, basically we will be talking about inanimate object as the first one inanimate objects of biological origin. So, in this context I will take you back to some of the most fundamental studies which were done almost I should say 40 to 45 years back while there are some people who are studying the thermoregulation behavior in the hornet nest. So, all of you must have seen a hornet nest at some place or other you know the hornest kind of in the corner of the buildings or somewhere and a very intense study was taken up somewhere in the Mediterranean in Israel by Jacob Ishe and other co-workers to figure out how these different nests of nature maintain regulate their temperature and in that journey of last 40 years what all has been discovered what are the different bioelectrical phenomena. So, in this the example will be the first example out here will be temperature regulation temperature regulation in hornet nest. So, the bioelectrical phenomena is out here is thermo electrical event. So, talking about thermo electrical event. So, we will be talking about some of the very basic events of nature like seabake effect, peltier effect. So, these are some of the most fundamental properties where thermal energy is being translated or transformed into electrical energy and vice versa electrical energy is dissipated in the form of thermal energy and there are materials which showed such behavior and those kind of materials are being utilized for refrigeration for active cooling and likewise there are several other applications of such devices. So, nature indeed has such interesting mechanisms to regulate temperature. So, the bioelectrical phenomena which will be dealing in the hornet nest is relevant to that what are the different current and voltages how they are regulating temperature and all those things and one of the instrumentation what will be involved in it basically will be talking about the electro meters which has the ability to. So, talking about the electro meters. So, electro meters are devices which can measure current of very very low amplitude very low magnitude like pico ampere nano ampere with high high end fidelity they can measure it. So, we will be talking about electro meters. So, now if you look at it in perspective. So, if you look at it that section one falls under all the different phenomena section two falls under the different events and section three is about the instrumentation because they are all interlinked with each other and advance applications of it. So, advance application of it is one of the applications is inspiration sustainable buildings. So, this is one of the major inspiration using bio compatible thermo regulatory mechanism. So, here I wish to highlight something. So, most of us who live in tropics or temperate countries during the summer we are totally dependent on an air conditioner. So, which basically essentially it does only one thing it pulls out the air molecules and reduces the collision and between the air molecules within a room using a very strong pump they sucking out air and thereby reducing the collision and making the room cooler that is what an AC does. Now, think of a situation and this process of pulling out air from a room needs enormous amount of energy these are all high power devices. Now, think of a situation if you can replace amount of energy which it needs could be replaced by something which is which can maintain the temperature of a room at within a very comfortable biological regime how that room will be how our life will be. So, these are some of the inspiration which we derive from nature and they intensely involve a whole lot of biological phenomena. So, this is this will be our first topic what we will be dealing with under the heading of system identification, biological phenomena measurement techniques and the advance applications the imagination tomorrow what will happen we do not know, but if we keep on doing this intense research one day the world may be a very different place. So, let us move on to the next one exactly under the same heading. So, again the system identification I will just put system ID as the first column then bio electrical phenomena as the second column then techniques I am just putting the short form and advance application a. So, the second thing we will be dealing with will be the world of insects what we learn from them. So, talking about insects, insects have evolved or probably one of the most evolved species on the floor of earth they have survived millions of years of turbulent weather turbulent climatic condition geological changes and they still survive and they have adapted several mechanism of energy conservation energy harvesting and several innumerable known and unknown survival strategies in order to ensure that they survive the onslaught of time the changing time. So, in that process some of these insects specially some of these hornets have developed certain mechanism by which they can perhaps sunlight and converted into energy exactly the same way a plant does. So, in other word within their body specially in their wings and in the abdomen they have certain specific molecules which functions as solar energy trapper they can trap the solar energy and they can convert that and in other word essentially what you are talking about they are living mobile solar cells. So, we will be talking about these kind of solar materials which are found in nature which has the ability to convert light energy into electrical energy. So, specially we will be talking about in the hornet and we will be talking about solar cells in hornet. So, in other word here we will be talking about the phenomena will be solar energy to electrical energy and of course, the different techniques which would be used will be mostly electrical measurement electrical signal measurement sorry and apart from it will have light signal quantification. And among that advanced application future energy harvesting to energy harvesting I should say strategy. So, we will pick up one example from the insect kingdom and we will talk about how the insects harvest energy from nature and this is something which could be a big inspiration for the future where as all of you have seen that silicon industry is almost hitting the roof crystalline silicon's efficiency is around 70 percent and 70 to 20 percent may be maximum that to in the lab conditions. So, there is intense search for molecules which are much easily available synthesized above more green and more biocompatible which does not need the extensive cost of processing silicon. So, in that line one approach I inspiration from nature is what I just now explained is in that lies in the cuticles of the hornets and if we could synthetically develop those compounds they may have immense potential to look forward. So, let us identify the third system from here again there will be four columns this time again the same thing system identification the column one s i system identification the biological or bioelectrical phenomena the instrumentation and advance applications. So, here we will be talking about the world of plants another very diverse kingdom and the only known biological system with its fullest ability could harvest sunlight gets the light converted into electrical energy in terms of flow of electron and helps us to synthesize helps to synthesize food in the food chain they are the auto tropes auto tropes auto means self tropes means they have the ability to synthesize food and we all depend on these auto tropes or our livelihood. So, they are kind of the pillars of the ecosystem based on those pillars all our the whole food chain is dependent upon. So, that is one of their most fundamental contribution apart from it they have wide range of sensors in their body they have touch sensors in the form of mimosa boutica they have touch sensor as well as mechanical can say touch sensor coordinated with a mechanical door in terms of venus fly trap where they could you know trap an insect, but that whole mechanism by which biology ensures a fantastic micro electromechanical system which all of you comes to the name of MEMS. So, biology already had these kind of MEMS in built in their system. So, that is an inspiration for those who are working in the domain of MEMS or miniaturization or mesoscopic devices it is a big inspiration. So, that is a third thing we will be dealing with apart from it the whole world is. So, beautiful because of the beautiful flowers all over the place and these beautiful flowers that is something very amazing actually they are the inspiration for dye sensitize solar cells those of you have heard like a grad cell cells after the name of grad cell who has done pioneering work in the field of dye sensitize solar cells. So, what are those different I should say different components of nature which contribute to develop different kind of dye sensitize solar cells because that is as I was telling in the previous slide that silicon is silicon technology is hitting the roof. So, we all are looking forward for next generation. So, dye sensitize solar cell is another one in that line. So, different ruthenium dye is different floral dyes and all those things which are derived from nature which is a basically an inspiration to develop the next generation of high end dyes. So, talking about the plant kingdom now that is what I have just narrated you. So, plant kingdom. So, within the plant kingdom will have a we will be talking about photosynthesis. Then we will be talking about the Mimosa pudica or touch me not for touch sensor this is for light to electrical to food. Then you have venous fly trap which is basically a biomems trap and then we will be talking about dye sensitize. So, the flowers flower dye or dye sensitized solar cells. So, the instrument here there are multiple instruments which are being used which are fairly common. Of course, you need the electro meters amplifiers whole lot of bio chemical techniques to study photosynthesis and you need the high end mims microelectromechanical systems and likewise several other instrumentation which is needed. And among the advanced application in terms of photosynthesis we are talking about artificial leaf I am coming to this or does that mean. So, say for example, we talked about photosynthesis. So, essentially what is happening on the leaf surface light is falling and this light energy ejects an electron a photon is being absorbed ejects an electron. And this electron through the cascade of to a pathway along the chloroplast leads to the formation of glucose molecule which is being consumed by our body. And of course, it goes through for system 1 for system 2 and the output of this is you are splitting a water molecule to oxygen as a by product and you are evolving hydrogen. So, there are two inspiration here the first inspiration is that making synthetic chlorophyll molecules which could be used for trapping solar energy and ejecting an electron that is one approach. The second approach is that So, coming back let me the second approach is that whatsoever we get inspiration in terms of the manganese cluster for splitting water. So, let me talk about at this line let me make one correction here and if this is one aspect of it is another aspect of it which is water splitting. And this is all taking place within the domain of photosynthesis and artificial leaf or we can add something else here also synthetic chlorophyll for solar energy artificial leaf or water splitting. So, understanding photosynthesis and emulating photosynthesis could have profound impact in our understanding of nature. This is one of the most fundamental reactions of energy conservation which is being followed by nature. So, we will go in depth into photosynthesis and we will talk about it and from there we will move on to the water splitting cluster which is part of the photosynthetic machinery. So, then we talked about Mimosa pudica or the touch sensors. So, these touch sensors they have been studied for almost last 100 years and some of the pioneering studies were done by Sir J. C. Bose and he made some very pioneering contribution and we will talk about his contribution where he talked about whether plants have nervous system or not. As a matter of fact in some of his philosophical transactions he had kind of hinted upon that these are rudimentary nervous systems of plants which could sense touch and we will talk in depth and what are the different devices which are being used and what is the current status of the field and which could be an inspiration for developing touch sensor for the future. So, we will talk about J. C. Bose's contribution touch sensor and while talking about these touch sensors I wish to highlight one more point that he is among those very first people Bose's among those first people who could show a functional semiconductor device in the form of gallon and we will talk about a little bit more. So, now coming back to the Venice flight trap here. Venice flight trap is a kind of device where which has a inbuilt touch sensor as well as a mechanical event. So, whenever an insect comes and sits there it stimulates the some part of the flower and there is a hood which closes in like this. So, in other words this is a touch sensor coupled with a mechanical door touch to mechanical door and this whole connection is could be an big inspiration future for developing MEMS based devices and which is purely an electrical and mechanical phenomena. So, we are talking about here a touch coupled with mechanical action this is what Venice flight trap will be studying and then we will be talking about some of the contribution made by professor Gratzel who is among the pioneer in developing a dye sensitize solar cells or Gratzel cells which is commonly known. So, we will be talking about some of those dye sensitize solar cells and basically talking about some of the contribution of professor Gratzel and his Gratzel cells or sorry and we will be talking about energy harvesting and in the previous slide while I was talking in previous to previous slide while we were talking about inanimate objects of biological origin I will have one more column which I have not mentioned. So, if this one is the first one. So, we talk about this will be the second one which is the world of insects and we talk about the third one insect plant kingdom. So, there are two more which are left actually I have not talked to you about the kingdom of animal which I will be anyway I will be talking in the next class and there is one more section which I will be introducing which is not very clearly highlighted in the course part is about some of the very primitive inorganic molecules which has some amazing electrical characteristics which has wide range of implication in biological processes and we will talk about those. So, I will close in here today we will continue here with the same graphical scheme of things in the next class and then we will move on to the different steps of the course. Thanks a lot.