 Good afternoon. It's good to hear. Let me introduce myself. I come from Kyiv, from the National Academy of Sciences of Ukraine. My institute is Institute of Semiconductor Physics, named after Lashkarov, one of the founders. I will talk today on surface plasma resonance sensing with application in biological objects and for health control. In this picture you can see our building, where we are working in our institution. Almost 20 years ago it was Institute of Cibernetics, but now we have 5 different buildings, where different labs and different departments are located, and you can go from one to another in 2-3 minutes. It's more close than even here. Our institution we have 4 different directions of investigation. First one is physics of interaction processes between electromagnetic radiation and matter, physics of low dimensional systems, micro and nanoelectronics, optoelectronics and solar power engineering, where exactly I am working with, science semiconductor materials, science and sensors systems. It's also related and we have department that collaborate with each other. And we have following divisions, division of optoelectronics, theoretical physics division, division of semiconductor optics, division of photoelectronics, surface physics and microelectronics, division of structural and mental analysis of semiconductor materials and systems, division on physical and technological problems of semiconductor infrared techniques, and division of technologies and materials of sensor techniques. Unfortunately, we are from developing country, but we have some new equipments that is known as common used equipment among academic sciences. For example, our institute have modern atomic force microscopy, Raman spectroscopy, good equipment, then the newest one X-ray research. Another institution has some femtosecond laser and we cooperate with each other and we can use all the institution equipment, not only our institute, but all the institutes of National Academy of Sciences of Ukraine. So a few words about our National Academy of Sciences. It's quite a big structure in Ukraine. We have almost 174 institutions where employed around 40,000 people, 40,000 scientists. This Academy of Sciences was founded in 1918 and simultaneously in this year, this person known as Boris Patton, he is president of National Academy of Sciences. He was also born in 1918 and still president of our Academy since 1858. So next year will be 60 year anniversary as he chair this National Academy of Sciences and will be also 100 year anniversary of our National Academy of Sciences and for this president. So everybody is invited to celebrate, to participate with number of conferences, number of journals, to publish, to exchange ideas, to cooperate with each other and I will continue now about science. So in my talk I will discuss shortly nature of plasmonics, plasmon excitation conditions, theoretical description of surface plasmon resonance, excitation configuration and coupling of light by different methods, type of modulation, sensitivity and ways to its increasing for different types of modulation, it's different, influence of surface micro geometry on resonant peak position, application of surface plasmon resonance method for biosensing. Surface plasmon resonant detector is placed on CD disc format and plastic substrate and introduction of plasmon 6 device for experimental session that part of you group number 4, 5, 6 already done this experiment and group number 1, 2 and 3 will continue, will do this experiment tomorrow evening, yes. So let's start from total internal reflection of light. This lecture will be just beginning in plasmonics, so it's very easily things, but somebody that is not familiar with this technique will shortly learn this, but if you want to go deeper to this science we can collaborate, we can use our, your techniques, your samples, our samples and in the future, but just only beginning introduction to plasmonics. So if you have a laser, if you have light penetrate from optically less dense medium, you just have refracted light and reflected light and probably a little bit absorption. But if your light propagates from optically more dense medium, in the interface of these two mediums we have also refracted light, reflected light and that's all. But, but if we use Snell's law in special condition in the limit case, in case of reflected light has 90 degree, in this case sine of 90 degree will be equal to 1 and for example if this is air let's consider refractive index also equal to 1. In this case we can calculate better and starting from this angle we will have total internal reflection and all the angles more exceed this, this better, all the light will be reflected fully. But if you put a small, doesn't matter, if you put some medium on the top of the surface it's better to put any conductive materials. It can be gold, it can be silver, it can be any metal and also semiconductor. Any material that has free electron any conductive material, even graphene, graphene. In this case light reflects usually reflects from the interface but this light also excite evanescent weight propagating across the interface of two mediums. If you have conductive materials it consists of career, for example free electrons and this light with its own frequency excite free electrons this material. In this case we excite evanescent wave and part of the full intensity coming to this interface is lost, is not lost but it's propagated here and we can view a deep in the reflected light because part of this intensity come across the interface and also this evanescent wave has decay exponential decay with this distance. So slowly we will start to continue with surface plasmon sensing so let's start from definitions few definitions so what is plasmonics and what is plasmon? This is quants of collective electron oscillation in conductive materials or in another words electron density waves. Surface plasmon resonance this evanescent wave is resonant excitation of plasmon in the conductive material between two medias with different refractive indexes for example glass and dielectric or liquid they have two different refractive indexes and surface plasmon is exciting just on the interface Surface plasmon surface plasmon polariton is electromagnetic wave that travel along a material dielectric or metal air interface this term explains that we have involves both charge motion and the in the metal and electromagnetic waves in the air or dielectric and localized surface plasmon resonance is the result of the confinement of surface plasmon on nanoparticle conductive nanoparticle of size of comparable to the wavelength or even less also now is very popular such structures as theorem 203 known as magnetite it often used as to excite magnetic resonance also known as plasmon resonance but in another words is magnetic because it is supported by increased magnetic permittivity of this material magnetite about nature of plasmonics in any metal we have from Drude theory we have its plasma frequency plasma frequency of metal if our light penetrate the metal to the interface with dielectric air or any other material with the refractive index n to the metal this light excite volume plasmon it has own frequency for different material it differs but approximately it in order of 10 in 16 power radians per second so if light penetrates to the interface of two medium we have this evanescent wave and this wave the case with distance from the top of this surface this is very important because we have limitation on materials we can sense for example we cannot we cannot measure refractive index of very big very big molecules we have limitation and the sensitivity the case from the surface so if we measure just on the surface some gas or liquids it will be good result but if our detection system is quite far for example 100 nm or up to 1 microns the sensitivity would be much much less so the necessary condition to excite surface plasmon we have a light with its k vector penetrating to the interface of two medium and we excite surface plasmon along the interface of two mediums with its own k vector so the projection of k vector of incident light is related depends on dielectric permittivity it's known as refraction index of prism for example and sine theta theta is the incidence angle of light beam coming to the interface so projection of this k vector on this plane will be this relation and projection of k vector to our plane should be equal to the k vector of evanescent weight known as surface plasmon surface plasmon is related with dielectric permittivity of metal that is on the interface it can be gold it can be silver, cuprum it can be semiconductor and also with dielectric permittivity of metal sorry, of dielectric dielectric that we are sensing on the surface so x component of incident photons weight vector should be close to the value of surface plasmon resonant weight vector the next condition to excite surface plasmon is epsilon of dielectric and epsilon of metal should have opposite signs in this case surface plasmon cannot interact with incident light coming to metal film and excitation of surface plasmon can be supported by total internal reflection using prism, diffractive grating or waveguide but it can be done only with people arised light only tm mode Why? Because hybrid states of non-uniform surface waves and electron plasma in metal can be excited only by people arised light E vector, electrical vector of light beam is located in incident plane XZ as you can see this is the incident plane of people arised light H vector in this case this is directed along Y axis Generation of surface charges requires electric field in both X and Z components Otherwise you cannot excite free electrons on the top of the metal coated prism I already told you about through the theory of free electrons in metals you can calculate dielectric permittivity of metal using frequency dependent from frequency of light dielectric permittivity absorption so finally this formula epsilon is equal to 1 minus omega plasmon over omega in square so this is plasma volume plasma frequency of metals it depends on electron concentration this is the constant electron charge mass of electron and epsilon zero I will try to show you short animation this is the model of free electron in metals so you can consider the surface of metallic films this is the electrons that have average travel path the average frequency of collision between each other and also also own frequency of oscillation here you can see animation of excited surface surface plasmon evanescent wave so you can see this is orientation of charges in the material that excited by incident light beam laser beam or spectral beam depends on different condition of excitation I will follow this little bit later how we can describe penetration of light to many layer system theoretically I will show you two approaches first one is very easy I think many of you familiar with this technique for example persons that are doing polarization macroscopy the person that is related with optical design it's almost the similar technique it's little bit different but the same approach so you have many many layer structure here is the beginning of our material first, second M layer is the last and now we have a beam going outside the system and of course we have reflected light here and we have transmitted light here and part of light of course will be absorbed here but we have also reflection at the interface of each layers reflection back and forward so we have final transition and final reflection of this system so we can describe this by easy approach by formulas we can build a matrix in this case E plus and E minus is coordinates of electric field electric field of light beam amplitude so here E plus and E minus is electric field of light at the first layer at the interface of first layer coming to our system E plus and E minus M M plus 1 is the coordinates is the electric field amplitude that exceed our system that transmit our system but not only transmit E plus is transmitted light going in forward direction and E minus is reflected light so this is the direction of propagation of our beams for calculation of this reflection coefficients can be taken from here we can calculate as matrix scattering matrix scattering matrix consist on interface matrix and propagation matrix and now I will shortly describe you maybe somebody of you used old techniques of calculation lenses now we have many modern programs but if you have some lens propagation of beam is very easy to build but if we have a number of lenses some elements with different refractive index can be quite difficult to make graphically how this beam propagates so one known method is to use matrix matrix that give coordinates of beam at the interface and matrix that show how beam propagates through the system so translation matrix and interface matrix same system is here but the difference is only with only with radius radius of this here we have spherical symmetry but in our case we have flat structures flat structures now we consider only flat structures so scattering matrix consist on interface matrix and propagation matrix interface matrix can be calculated using Fresnel coefficient of reflected light each interface and transmitted light at each each interface using Fresnel relation known relation is you can see here so if you can computer you can program very easily you can also try to do by yourself manually and L matrix is propagation matrix it describe absorption of light in each layer of course this propagation matrix absorption of light depends on absorption coefficient of each layer and its refractive index because they are related as usual and to build the scattering matrix you can multiply each of these matrix starting from M M plus 1 layer and back to first one each of these matrix as you can see has two rank second rank after multiplying the scattering matrix will be also second of second rank in this case reflection of many layer structure can be calculated using appropriate elements of matrix of scattering s so this reflection will be s21 over s11 so this and this element s12 and s22 is related with another phenomena using this system I show manual system here is theoretical calculation here is theoretical calculation of reflectance deep inner reflectance spectra or silver its first curvature and gold thin films too you can see that silver has more narrow bend than gold and they also shifted in angular position so the minimum of silver film is related to 60 and approximately half degree and the gold is related approximately 63 degrees in this calculated spectra this is not experimental, this is calculated one the second quantum approach to calculate position reflectance spectra of our plasmonic materials you can use this function this calculation, this approach is different from the previous one by taking into account polarization and surface concentration of molecular layer on our metallic film by applying green function as photon propagator we can write this equation photon propagator is a green function that give us the probability of traveling a charge between position 1 and position 2 in a known time interval plus and minus is for illustration I will show plus and minus is propagation direction so we have here plus area, positive area, negative area so propagation plus 1 is this direction propagation is minus plus this direction plus plus is reflection minus minus is such reflection so considering electrical vector equal to reflectance multiply on the first electrical vector on the first layer the total total equation for reflected light can be written as this very big formula you can easily calculate this if you know surface concentration of molecules if you can build photon propagator permittivity of molecules in each layer electric field that coming to our system inside and and reflection you can calculate known all these all these values so as I told here is the illustration of our negative and positive area taking to account this formula I show you before we can understand that total reflection will be the sum of the general simple Fresnel reflection and reflection caused by polarization and concentration of molecular layer this one so if you don't consider this, if you use matrix method you will lose this part very important if you have not flat structure if you have materials metal materials that is not flat but island structure localized surface plasma so if you have nanoparticles metal nanoparticles not even metal it can be semiconductor in this case in this case you can use not very simple simple Mi theory to describe these materials Mi theory is a scattering of light by spherical particles by spherical nanoparticles and if you know there are three cases if wavelength is if our particles less wavelength if they are comparable and the next and the third part if wavelength is much more than average dimension of nanoparticle so the electric function real and imaginary part of the electric function can be calculated by this equation using plasma, volume plasma frequency tau bulk is the constant is 9.3 to 10 in minus 15 power seconds relaxation time for me speed as written here you can calculate effective relaxation time and based on this calculation equation you can calculate refractive index of the material and absorption coefficient of this material used real and imaginary part of the electric permittivity here are few configurations how to couple light by surface plasma method first one is common used Kretschmann method you have seen this on our lab it's a prism but we have another type of prism this is a prism so here is penetrate a light laser for example ok it doesn't matter a light that reflects and excite a surface plasma that exponentially decays the distance so here we can observe this direction reflected light and if we have surface plasma it will be lost of some reflection coefficient if we observe deep at the reflectance specter it will be intensity of our plasma and we can calculate position and the width average width of this band ok, 2 layer Kretschmann configuration it differs by adding one more layer and another one is auto configuration the difference between Kretschmann and Otto is the metal film is after the prism so we have liquid so in first configuration we measure our liquid or gas on the surface of this metal film in Otto configuration our materials to be measured is located between prism and metal here we have excited plasma resonance peak but for Kretschmann configuration the sensitivity is much better than Otto that's why this method is more popular than this one also we have some other different methods for exciting surface plasma it's scanning near field optical scanning near field optical microscopy probe so we have a probe it excites metallic very thin it excites near field here in the interface and we can have surface plasma this is method using diffraction grating for excite surface plasma resonance and using diffraction future surface nanoparticles independently from this case there are three known methods for coupling light to the surface plasma first one as I told you prism method so light coming from outside to prism then from optically more dense medium we have total internal reflection and excitation of surface plasma here and this surface plasma is related with refraction index of this medium and in this case we can measure this refractive index very precisely so the accuracy of this method is around 5 digit after comma but this is not the most huge not the most accurate method accuracy can be higher this is waveguide method this is waveguide method to excite surface plasma so we have just waveguide and we can deposit thin metallic films or island structure of nanoparticles, metal nanoparticles and attach small cuvette at measure refractive index of this cuvette just on the top of this waveguide this is one of the most popular method because you don't need expensive prisma and you can make this device very small very small and easy to use outside in field in any condition outside lab and diffraction grating so you can excite plasma by diffraction grating and light penetrate into the system by diffraction on these futures sometimes diffractive method overcome this prisma method because the band of reflectance band of plasmon is more narrow so the full width of this spectral reflectance curve has less dimension so you can calculate diffraction index more precisely we have four types of modulation for calculation of refractive index of plasmon first one is common used angular modulation this is excitation by monochromatic wave by changing the incident angle so as some of you see the lab we can scan the angle and look where this plasmon exciting highly so this surface plasmon observed as a deep in the angular spectrum of reflected light and our sensor output is the incident angle yielding the strongest coupling the second popular method is spectral method by wavelength modulation we can use modulated collimated polychromatic light you can use monochromatic or prism or diffractive grating to make spectral to make spectra from the white light and this surface plasmon will be observed as deep in the wavelength spectrum of reflected light and sensor output will be the wavelength yielding the strongest coupling and some original methods as intensity modulation you use single wavelength you use single angle and you just modulate intensity so you increase or decrease intensity of light and look when when surface plasmon will be the highest and one of the most precise method is phase modulation so you can use excitation by shift of phase of the light wave at single incident angle and wavelength so the single wavelength but you change the phase and look when surface plasmon will be bigger according related with the phase each of this method has its own sensitivity so here in the table you can look approximately sensitivity of each of each method of modulation so for intensity modulation our resolution of r i u is 10 in minus 5 for angular spectroscopy it's possible to take almost 10 in minus 7 but you can use additional things to compensate some noises and some other phenomena for frequency spectroscopy we have 10 in minus 6 and the most the better resolution we have for fast shift measurement but what is not good for this method we have very low dynamic range of measurement so fast phase shift can be measured only at 10 in minus 4 power order that's why we have measurements we have limitation for this method but for resolution is the best one okay here you can compare for localized surface plasmon different geometry of nanostructures here the sensitivity for nano-romes nanospheres, nano-pyramids and needles, needle structures so sensitivity can be calculated as argument of each of these methods okay for spectral for example for spectral modulation a will be lambda so s spectral sensitivity will be delta lambda over delta n so you can see that the best sensitivity can be observed for needle structure little bit less for nano-pyramids and the lowest one for nanospheres nano-romes has the medium medium value but total sensitivity is not exactly thing that we can operate is better to operate but by figure of merit can be calculated as this sensitivity over full width of this curve at the middle height and you can compare that this the most sensitive structure for needles has the lowest figure of merit here because the bend has big width is better to use for more precise measurements is better results can be shown for nano-pyramids yes here is 40 nanometers per riu but here is the maximal value okay ways to increase sensitivity if we have angular modulation we can add additional diffractive grating we can stabilize temperature and noise so our bend will be more narrow for wavelength modulation we can use 3 spectrometers and other techniques multi-channel sensing and thus we can go up to or down to 2 at 10 in minus 7 riu for intensity modulation we can use 2 light sources with little bit different wavelength so thus we can get this sensitivity for phase modulation we can use first one is interference pattern analysis so you just look on the diffractive interference picture and estimate this modulation so you can analyze this interference pattern and improve your result by some additional optical elements you can use ellipsometry and make difference appropriate calculation in this way you can you can get this sensitivity almost 10 in minus 8 power riu and you can use heterodynes if you have different wavelength so the interaction will give frequency few orders less and you can detect this phase by general phase and universal methods that can be used for every type of modulation is use dielectric nanocortins using graphene to increase sensitivity using nanoparticles metallic nanoparticles use magnetic magnetite for increase magnetic permittivity here you can compare influence of forms of molecules on SPR resonance so some of biological molecules are known as elliptical elliptical form but orientation of these ellipses can be extended in horizontal in vertical direction or extended in horizontal direction so we can compare surface plasma resonance response in relation with orientation of such elliptical molecules on this graph you can see the reflectance spectra surface plasma resonant peaks that related to different type of molecules so first one is the empty surface so no molecules only sensing element only chip so we can first curve have the angle at 62 0.747 if we have shortened molecules is this so second is extended in horizontal direction so our angle shift to the higher degrees this is the second curve pre we have extended molecules in vertical direction so we have and our theta even more and number 4 is extended molecules by but the factor is little bit less than here this is the relation between A and B of ellipse you can see the maximal angle of our surface plasma resonant peak and here is another situation we have calculated surface plasma resonance dependence of structure molecular film consist from both vertically extended and horizontally extended molecules so first one is only ok first is only extended molecules vertically extended molecules we have theta here and second one is half of extended in horizontal direction and half is extended in vertical direction so as you can see if you have mixture of two molecules our angle of surface plasma shifts a little bit ok one of the method to to influence on surface resonant peak to make tuning you can use elastic substrate in this picture you can see and compare nanoparticle structure on solid substrate and the same on elastic substrate for elastic substrate can be used polymer poly dimethyl siloxane known as PDMS so after the position and including nanoparticles in this matrix you can make this material ok you can make wider, shorter you can modify and your peak of your plasma will shift and the curve will change its shape so this is the method you can negotiate and you can influence on your system by many much more parameters than only spectral or angular modulation ok here is the scheme of biological analysis for simple scheme that is known as direct detection of system sandwich detection format as you can see here competitive detection format and inhibition detection format so it's related in the position of analyte of antibody, antigen its interaction and so on я вот ли briefly explain you the method and the device developed in our institution it's the surface plasmon resnan sensor based on disk format so you can use just known CDROM or DVDROM device and you can use old factory that producing CD and DVD disk using the same material you can produce a sensor multi-element sensor you can put here over 50 samples to measure in one way so here is the general scheme of this detector this is optical element so laser light of this CDROM comes to the plastic sensor ok to produce this sensor of course we should code it by some of metals for example gold maybe silver depends on your situation but of course gold has less reactivity with chemicals so gold is preferable but this gold will be deposited on plastic substrate not glass and it works we have patent of Ukraine of this technology and this device is under way to commercialization so I will show you more detail the scheme of this device so here we have such elements this is part of disk here later collimated light you can polarizer so light comes here here we have diffractive elements then mirror outside and our element with cuvette here you can put your liquid that is necessary to measure when light comes to detector so here is single wavelength single angle but you can make holes, make detectors for any case you need to measure just refractive index you can measure chemical reaction you can measure anything you want by use up to 100 channels simultaneously here is the general scheme of device you have seen in our lab SPR6 device surface plasmon resonance that is used angular modulation and as you can see here is the configuration of prism is made by special method that light comes from the laser reflects at the same direction so you don't need to rotate laser and detector as in ellipsometers as in triangle prism this prism has better configuration you can just rotate your prism and light coming to prism will reflect at the same angle and come to detector for measurement Group 1, 2 and 3 can enjoy this experiment tomorrow it will be I think more easier and more quick detection we prepare this and anybody that bring samples with you can find our guys Gleb and Maxim to measure own samples using this device we are here until Saturday so everybody is invited this is the characteristics of this surface plasmon resonance plasmon 6 refractometer so as you can see refractive index can be measured this accuracy of this device is 5 at 10 in minus 5 power but of course this is without thermal stabilization box in Ukraine we have thermal stabilization box but it's enough take space so we didn't bring this it can be even improved so this is the detection limit variation resolution measurement time laser excited laser power weight and it also comes with software build especially for this series of devices ok I think today is enough so for conclusion I'd like to say that surface plasmon resonance method all to detect charges changes of refraction index up to 10 in minus 8 power refractive units this is good for measurement of low concentration solution various configuration available depends on your needs and your availability of materials it's possible to detect organic and also organic liquid solution gas solution including sites red blood cells viruses, proteins etc this is non-expensive technology as you have seen before from CELMIC company device is very easy to build and the cost is even less than our device so the technology is not expensive possibility to use multi-channel detection and the effectivity of CD disk format biosensor that can be used for big data analysis of these our materials in the end of my talk I'd like to thanks ICTP the international center for theoretical physics for invitation and for my colleagues Maria Luisa Calva Alberto Cabrera, Nicoleta Tosa and Alberto de Aspro Special thanks to local organizers Johnny Miller and Micho Danaylov and for our secretary Federica del Conte Special thanks to Ukraine International Airlines for giving us tickets for fuel just for fuel really they are our sponsor and for all Ukrainian team they give us I just made calculations so it's exactly for this kind very appreciate this kind of service and to our society our sponsors SPI International Society for Optical Engineering Optical Society of America International Commission of Optics that today evening will be a special reception after award ceremony and Optics within Life Science Society here I can shortly invite you to submit paper to our journal we have tradition each institute of our almost each institute of our academy have own journal as we have seen 174 institution it means that more than 100 journals we have each institution published but it's different topics it can be mathematics, geology and so on but here in Ukraine according to national library of Ukraine we have the most among Ukraine and also we use cross-reference data we start to make DOI number and cross-reference data so due to statistics we have first and second number for citation in Ukraine so I invite you who is interested to submit paper here because it's open access and it's free no payment for submission for distribution and general time before submission and acceptance is from 3 to 5 months occasionally it can be only one month sometimes so this is the journal of the page journal SPQEO means semiconductor physics quantum electronics, optoelectronics so we have as I told open access free publication 32 research databases of EPSCO we have quick processing double blink blind peer review system we have DOI and cross-reference for numbers per year we have in time publication and hope to submit this year for SCOPUS and Thomson Raiders yes, yes so this is I think enough субтитры