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Mod-01 Lec-02 Bio electricity

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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 be dealt with, and I also
highlighted the fact that each of the modules will be standalone. So you really can pick
up any module and go with read. So today what we will do is, I will give you a graphical
outline of the way that course will progress, so that will kind of giving an idea where
everything fits in, because whenever we do a course, kind of you lose track like what
is the central theme, how this whole course in its structure. And especially in a field like bioelectricity which is so diverse from in animate object
to animate object, the insect world, the world of plants and everything. So, where this all
these things kind of converged, where really why we divide time. So today’s class will
be kind of giving you on overall outline, the flow diagram – how you are going to
progress; of course, your five modules will remain there. Those are the five modules,
we will 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
all other integral theme or I should say the central theme behind this whole exercise of
forty lectures. 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 bio-energy, application all over the place.
So the way I am going to put the graphical representation just let me give a verbal idea
about it. So first of all, it would be in a tabular fashion depicted. So in the left
most column, we will talk about the system which will be starting, 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 will talk about the examples under those headings. Then 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 studies. 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 of the system, and the tools employing into 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 I will 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 to the so this where
we are Bioelectricity, this is lecture two and the title of the this class will be the
Graphical Representation of the Diverse Bioelectrical Events and Their 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 step. After the system identification, we will move onto bioelectrical phenomena
of that system. Next we will talk about the measurement techniques; how we are you know, measurement techniques. And then applications. we will talk about the advance And I expect you people to kind of keep this, so what I expect is that I want this to be a act as a guiding principle or should be part of your brain map. So whatever in the next rest of the classes
what I will be teaching, rest of the course, you should always try to correlated with where
exactly all those small pieces are in formation or particles are fitting. So at the end of
it, you should have a very holistic picture of nature how nature is surround it or pretty
much bioelectrical phenomena is should say a integral part of the evolution of nature
itself. And whatever we studying 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 law 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 you 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 them most fundamental studies which were done almost I should say forty
to forty-five years back, while there are some people whoever studying the thermal regulation
behavior in the hornet nest. So all of you must have seen the hornet nest at some place
or other, you know the hornet nest, it is kind of in the corner of the building or somewhere.
And a very intensive study was taking up somewhere in medetrienian in his rail by Jackup and
other coworkers to figure out, how these different nests of nature maintain regulate their temperature.
And in that journeying of last forty 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 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 sea beck
effect, Peltier effect. So these are some of the most fundamental properties where thermal
energy is being translated or transforming to electrical energy and vice versa, electrical
energy is dissipated in the form of thermal energy. And there are materials which show
such behavior and those kind of materials are been utilize for a refrigeration, for
active cooling and likewise. There are several other applications of such such devices.
Nature indeed has such interesting mechanism 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 voltage is, how they are regulating temperature and all those things. And one
of the instrumentation what will be involved in it basically will be, we talking about
the electrometers, which has the ability to so talking about the electrometers. So electrometers
are devices, we can measure current of very very low amplitude, very low magnitude like
pico ampere, nano ampere with high they can measure it. So we will be talking about electrometers.
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 to each other. And advance
applications of it, so advance application of it is one of the application inspiration
for 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 whole
eleven are countries, during the summer, we are totally dependent on a air conditioner,
so which basically essentially 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, thereby reducing the collision and making the room cooler,
that is what A.C does. So think of a situation and this process of
pulling out air from a room needs enormous amount of energy, these are all high-powered
devices. Now think off a situation, if you can replace a amount of energy which it needs
could be replaced by something which is which can maintain the temperature of a room at
a 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 intensively
involved whole lot of biological phenomena. So this is, this will be our first topic what
will be dealing with under the heading of system identification, bioelectrical phenomena,
measurement techniques and the advance applications – the imaginations. Tomorrow what will happen
we do not know, but if we keep on doing this intensive research one day the world may be
a very different place. So let us move onto the next one, exactly
another same heading. Again the system identification, I will just put system ID in the first column,
then bioelectrical phenomena is the second column, then techniques – I’m just putting
the short form and advance application A A. So the second thing will be dealing with will
be the world of insects. What we will 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 conditions, geological changes and
they still survive. And they have adopted several mechanism of energy conservation,
energy harvesting, and several innumerable known and unknown survival strategies. In
order to ensure that they survive on lots of time, the changing time; so in that process,
some of these insects, especially some of the hornet have developed certain mechanism
by which they can sunlight and convert it into energy. It exactly the same way of plant
does. So in other word, within their body especially
in their wings and abdomen, they have certain a specific molecules, which functions as solar
energy dropper. They can drop the solar energy and they can covert that; and in other word,
essentially what we are talking about they are living mobile solar cells. So we will
be talking about these kinds of solar materials, which is found in nature, which has the ability
to convert light energy into electrical energy. So especially will be talking about in hornet
and will 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 signal measurement sorry. And apart from it,
will have light signal quantification. And among that advance application, future
energy harvesting to energy harvesting I should say strategy. So will pick up one example
from the insect kingdom and we will talk about how the insect harvest the energy from nature.
And this is something which could be a big inspiration further future, where as all of
you have seen that silicon industry is almost hitting the roof, crystalline silicon efficiency
around seventeen percent, and seventeen to twenty percent, may be maximum in the lab
conditions. So there is intern search from molecules, which are much easily available,
synthesize at all, more green and more. It 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 the lies in the cute hoods 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 are four columns this time again the same thing system identification – the
column one, SI – 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 very diverse kingdom and the only known biological system, which
with its fullest ability could harvest sunlight; get the lights, converted into electrical
energy in terms of flow of electron and have to synthesize, have to synthesize the food.
In the food chain, they are autotrap, auto means self, trap means they have the ability
to synthesize food and we all depend on these autotraps for 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 ange of sensors in their body. They have touch sensors in the
form of mimosa pudica, they have touch sensor as well as mechanical you can say touch sensor
coordinate with the mechanical door, in terms of Venus Fly Trap, where they could you know
trap on insect. But that whole mechanism, by which biology in shears are fantastic micro
electromechanical system, which all of you comes in a name of MEMS. Biology already have
these kind of MEMS inbuilt in their system, so that’s an inspiration for those who are
working in the domain of MEMS or miniaturization or microscopic devices, it’s the big inspiration, so that is the 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, there are something very amazing actually. They
are the inspiration for dye sensitizes solar cells. Those of few of the name of grid cells,
who has done pioneering work in the field of dye sensitizes solar cells. So what are
those different should say different components of nature which contribute to develop different
kind of desensitize solar cells, because that is as I was telling in the previous slide
that silicon is silicon technology is hitting the roof. So, we are all looking forward for
next generation. So desensitize solar cell is another one in that line. So different
ruthonium dyes, different floral dyes and all those things, which are derived from nature,
basically which is inspiration to develop the next generation of high end dyes. So talking
about the plant kingdom now. Let us what I just narrated you, so plant
kingdom. So within the plant kingdom, we will have A, we will be talking about photosynthesis.
Then we will be talking about the mimosa pudica or touch me not or touch sensor. This is for
light to electrical to food. Then you have Venus flytrap, which is basically a Bio-MEMS
traps. And then will be talking about dye sensitize, so the flowers – flower dyeing
or dye sensitized solar cells. So the instruments here, there are multiple instruments, which
are being used, which are fairly common’ of course, you need electrometers, amplifiers.
You need whole lot of biotechnical techniques to study photosynthesis and you need a high
end MEMS – micro electromechanical systems, and likewise several other instrumentation,
which is needed. And among the advance application, in terms of photosynthesis, we are talking
about artificial leafs, I am coming to this, what does it does that means.
So say for example, we talked about photosynthesis. Essentially what is happening, on the leaf
surface light is falling, and this light energy ejects an electron, a photon is remaining
absorbed, ejects an electron and this electron through the cascade of to the pathway along
the chloroplast leads to the formation of glucose molecules, which is being consumed
by our body. And of course, it goes for system one, for system two and the output of this
is you are splitting a water molecule to oxygen as a byproduct, in evolving hydrogen. So there
are two inspiration, 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 whatever
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 this is one aspect of it, this 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 for water splitting. So understanding photosynthesis
and emanating photosynthesis could have profound impact in our understanding of nature. And
this is one of the most fundamental reactions of energy conservation, which is being followed
by nature. So we will go in depth in photosynthesis and we will talk about it, and from there
we will move onto 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 a study for a almost last hundred years and some of the pioneering studies was
done by Sir G. C Bose. – Jagadesh Chandrabose. And he made some very very pioneering contribution
and we will talk about his contribution where he talked about with the plants have nervous
system or not, as [FL] fact in some of his fellows tropical transactions he has kind
of hinted upon the 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
and talking about touch sensors. And while talking about the touch sensors, I wish to
highlight one more point that he is among the very first people, Bose is among those
first people who could show a functional semiconductor device in the form of galvanic. We’ll talk
about it little bit more. So coming back to the Venus flytrap ok, Venus flytrap is a kind
of a device where which is a inbuilt touch sensor as well as a mechanical event. So,
whenever insects 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 touch sensors coupled
with a mechanical door, touch to mechanical door and this whole connections is could be
a big inspiration feature for developing MEMS based devices, and which is purely an electrical
and mechanical phenomena. So we talking about clear touch coupled with
mechanical action, this is what Venus flytrap will be starting. Then we will be talking
about some of the contribution made by Professor Gratzell who among the pioneer in developing
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 Gratzell and his Gratzel cells one second sorry and will be talking about
energy harvesting. And in the previous slide, while I was talking
previous to previous slide where we are talking about inanimate objects of biological origin.
I have one more column which I have in mentioned, so if this one is the first one, so we talk
about this will the second one which is the world of insects. And we talk about the third
one, plant kingdom. So there are two more which are left actually,
I have talk to about the kingdom of an animal, which will be anywhere I will be talking in
the next class. 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 characteristic which has wide range of implication
in biological process 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 onto different steps of the course. Thanks a lot.

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1 thought on “Mod-01 Lec-02 Bio electricity”

  1. Moises Parra says:

    It is a great help for me, we are in a great time for learn all we want learn. Thank you!!!!

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