Nanoplasmonic metamaterials for a new generation of chemical, biochemical and biological sensors

Potreba za osetljivim senzorima hemijskih, biohemijskih i bioloških agensa u današnjem svetu sve je veća, od industrije, preko biomedicine, do očuvanja okoline i protivterorističke odbrane. MeĎu najosetljivijim i najsvestranijim napravama ove vrste su elektromagnetni senzori, naročito oni koji svoju funkciju zasnivaju napovršinskimplazmonima-polaritonima (surface plasmons polaritons, SPP) na meĎupovršini metal-dielektrik. Sa dolaskom nanotehnologija otvorila se mogućnost da se proizvedu metal-dielektrični nanokompoziti, čime je omogućen novi stepen slobode u dobijanju SPP senzora i stvorena nova grana elektromagnetne optike koja je nazvana plazmonika. Posebno bitan proboj predstavljaju elektromagnetni metamaterijali koji se mogu definisati kao veštačke strukture sa elektromagnetnim, odnosno optičkim osobinama, kakve se ne pojavljuju uobičajeno u prirodi. Moţda najpoznatiji primer sutzv. „levoruki“ metamaterijali, strukture čiji efektivni indeks prelamanja u odreĎenom opsegu talasnih duţina dostiţe negativne vrednosti.Ova disertacija okrenuta je razmatranju upotrebljivosti plazmonskih metamaterijala za visoko osetljive senzore hemijskih, biohemijskih i bioloških agensa. Osnovna ideja je da se kontrolisanim strukturiranjem metal-dielektričnih nanokompozita obezbedi projektovanje novih elektromagnetnih modova. Oni će se zatim iskoristiti za prevazilaţenje principskih ograničenja konvencionalnih plazmonskih senzora i povećanje njihove osetljivosti i selektivnosti.Koncept metamaterijala s jedne strane daje mogućnost inţenjeringa frekventne disperzije i time formiranja optičkih modova neostvarivih u prirodnim materijalima, a s druge dozvoljava modifikovanje prostorne disperzije, odnosno kontrolisano menjanje optičkog prostora (tzv. transformaciona optika). Jedna od osnovnih posledica ovoga jeste mogućnost lokalizovanja optičkog polja na duboko podtalasne domene, što dovodi do drastičnogpovećanja osetljivosti hemijskih, biohemijskih i bioloških senzora. Druga posledica je mogućnost formiranja plazmonskih nanokompozita koji uvoĎenjem novih modova omogućuju selektivno očitavanje prisustva ciljanih agensa. Najzad, u takvimvstrukturama konstrukcijski se obezbeĎuje efikasna spregasa snopom za očitavanje, što je jedan od velikih problema kod konvencionalnih SPP senzora...The need for sensitive sensors of chemical, biochemical and biological analytes in the contemporary world is ever increasing, from industry, to biomedicine, to environmental protection and homeland defense. Among the most sensitive and most versatile devices of this kind are electromagnetic sensors, especially those with their function based on surface plasmons polaritons (SPP) at a metal-dielectric interface. The advent of nanotechnologies ensured a possibility to fabricate metal-dielectric nanocomposites, thus ensuring a novel degree of freedom in the fabrication of SPP and creating a new branch of electromagnetic optics, the plasmonics. An especially important breakthrough are electromagnetic metamaterials that can be defined as artificial structures with electromagnetic or optic properties which do not occur usually in nature. Maybe the best known example are the so-called "left-handed" metamaterials, the structures whose effective refractive index in a given wavelength range reaches negative values.This dissertation is dedicated to a consideration of the applicability of plasmonic metamaterials for highlysensitive sensors of chemical, biochemical and biological analytes. The basic idea is to ensure the design of new electromagnetic modes through controlled structuring of metal-dielectric nanocomposites. These modes are further used to overcome the fundamental limitations of conventional plasmonic sensors and to increase their sensitivity and selectivity.The concept of metamaterial from one side offers an opportunity to engineer the frequency dispersion and thus to design optical modes unattainable in natural materials, while from the other side it allows the modification of the spatial dispersion, i.e. controlled changing of the optical space (the so-called transformation optics). One of the main consequences is the possibility to concentrate the optical field into deep subwavelength domains, which leads to a drastic increase of the sensitivity of chemical, biochemical and biological sensors. Another consequence is the possibility to form plasmonic nanocomposites which by introducing new modes ensure selective readout ofviithe targeted analytes. Finally, the geometry of such structures ensures efficient coupling with a readout beam, which is a large problem with the conventional SPP sensors..

Nanoplasmonic metamaterials for a new generation of chemical, biochemical and biological sensors

Potreba za osetljivim senzorima hemijskih, biohemijskih i bioloških agensa u današnjem svetu sve je veća, od industrije, preko biomedicine, do očuvanja okoline i protivterorističke odbrane. MeĎu najosetljivijim i najsvestranijim napravama ove vrste su elektromagnetni senzori, naročito oni koji svoju funkciju zasnivaju napovršinskimplazmonima-polaritonima (surface plasmons polaritons, SPP) na meĎupovršini metal-dielektrik. Sa dolaskom nanotehnologija otvorila se mogućnost da se proizvedu metal-dielektrični nanokompoziti, čime je omogućen novi stepen slobode u dobijanju SPP senzora i stvorena nova grana elektromagnetne optike koja je nazvana plazmonika. Posebno bitan proboj predstavljaju elektromagnetni metamaterijali koji se mogu definisati kao veštačke strukture sa elektromagnetnim, odnosno optičkim osobinama, kakve se ne pojavljuju uobičajeno u prirodi. Moţda najpoznatiji primer sutzv. „levoruki“ metamaterijali, strukture čiji efektivni indeks prelamanja u odreĎenom opsegu talasnih duţina dostiţe negativne vrednosti. Ova disertacija okrenuta je razmatranju upotrebljivosti plazmonskih metamaterijala za visoko osetljive senzore hemijskih, biohemijskih i bioloških agensa. Osnovna ideja je da se kontrolisanim strukturiranjem metal-dielektričnih nanokompozita obezbedi projektovanje novih elektromagnetnih modova. Oni će se zatim iskoristiti za prevazilaţenje principskih ograničenja konvencionalnih plazmonskih senzora i povećanje njihove osetljivosti i selektivnosti. Koncept metamaterijala s jedne strane daje mogućnost inţenjeringa frekventne disperzije i time formiranja optičkih modova neostvarivih u prirodnim materijalima, a s druge dozvoljava modifikovanje prostorne disperzije, odnosno kontrolisano menjanje optičkog prostora (tzv. transformaciona optika). Jedna od osnovnih posledica ovoga jeste mogućnost lokalizovanja optičkog polja na duboko podtalasne domene, što dovodi do drastičnogpovećanja osetljivosti hemijskih, biohemijskih i bioloških senzora. Druga posledica je mogućnost formiranja plazmonskih nanokompozita koji uvoĎenjem novih modova omogućuju selektivno očitavanje prisustva ciljanih agensa. Najzad, u takvim v strukturama konstrukcijski se obezbeĎuje efikasna spregasa snopom za očitavanje, što je jedan od velikih problema kod konvencionalnih SPP senzora...The need for sensitive sensors of chemical, biochemical and biological analytes in the contemporary world is ever increasing, from industry, to biomedicine, to environmental protection and homeland defense. Among the most sensitive and most versatile devices of this kind are electromagnetic sensors, especially those with their function based on surface plasmons polaritons (SPP) at a metal-dielectric interface. The advent of nanotechnologies ensured a possibility to fabricate metal-dielectric nanocomposites, thus ensuring a novel degree of freedom in the fabrication of SPP and creating a new branch of electromagnetic optics, the plasmonics. An especially important breakthrough are electromagnetic metamaterials that can be defined as artificial structures with electromagnetic or optic properties which do not occur usually in nature. Maybe the best known example are the so-called "left-handed" metamaterials, the structures whose effective refractive index in a given wavelength range reaches negative values. This dissertation is dedicated to a consideration of the applicability of plasmonic metamaterials for highlysensitive sensors of chemical, biochemical and biological analytes. The basic idea is to ensure the design of new electromagnetic modes through controlled structuring of metal-dielectric nanocomposites. These modes are further used to overcome the fundamental limitations of conventional plasmonic sensors and to increase their sensitivity and selectivity. The concept of metamaterial from one side offers an opportunity to engineer the frequency dispersion and thus to design optical modes unattainable in natural materials, while from the other side it allows the modification of the spatial dispersion, i.e. controlled changing of the optical space (the so-called transformation optics). One of the main consequences is the possibility to concentrate the optical field into deep subwavelength domains, which leads to a drastic increase of the sensitivity of chemical, biochemical and biological sensors. Another consequence is the possibility to form plasmonic nanocomposites which by introducing new modes ensure selective readout of vii the targeted analytes. Finally, the geometry of such structures ensures efficient coupling with a readout beam, which is a large problem with the conventional SPP sensors..

Experimental and numerical determination of tube collision energy absorbers characteristics

Razvoj apsorbera energije sudara je jedna od neophodnih mera pasivne zaštite putničkih vagona. Uloga pasivne zaštite je da posledice sudara svede na najmanju moguću meru. Apsorber razvijan u ovom radu sastoji se od čeličnih bešavnih cevi u kvalitetu P235T1 i konusne čaure napravljene od čelika za poboljšanje u kvalitetu C45E. Tokom sudara provlačenjem cevi kroz konusnu čauru dolazi do redukcije - smanjenja prečnika cevi pri čemu se troši energija. U radu su analizirani rezultati dobijeni numeričkim simulacijama i dinamičkim ispitivanjima cevnih apsorbera kinetičke energije sudara putničkih vagona. Glavni cilj rada je uspostavljanje korelacije rezultata dobijenih numeričkim simulacijama i eksperimentalnim istraživanjima. Korišćenjem karakterističnih parametara dobijenih tokom kvazi-statičkih, dinamičkih ispitivanja i numeričkih simulacija, definisane su vrednosti ključnih parametara koje se mogu koristiti za buduća ispitivanja cevnih apsorbera ovog tipa pri brzinama većim od 20 km/h. Numeričke simulacije se mogu koristiti u fazi razvoja apsorpcionih elemenata dok je za konačnu ocenu prototipa neophodno uraditi dinamička ispitivanja.Development of collision energy absorbers is one of the necessary measures for passive safety of passenger coaches. The purpose of passive safety is to minimize the collision consequences for passengers. The collision absorber developed in this work consisted of a low carbon seamless steel tube and conical bush fabricated from quench and tempered carbon steel. During collision, the seamless tube is compressed into a bush with a reduced diameter. In this paper, the analysis of results is obtained by numerical simulations and dynamic investigation of tube absorbers of kinetic collision energy of passenger coaches. The research focuses on correlations between numerical and dynamic test results. Using the characteristic parameters obtained by the dynamic tests and numerical simulations, values for key numerical parameters have been defined, which can be used for further investigations of tube shrinking absorber. Numerical simulations should be used in the developing phase of a prototype, while for the final verification it is necessary to do dynamic (impact) test

Vacuum Fluctuations in Optical Metamaterials Containing Nonlinear Dielectrics

We investigated the influence of zero-point fluctuations (vacuum fluctuations, optical quantum noise) to the optical response of electromagnetic metamaterials containing dielectrics with third-order Kerr-like nonlinearity. We determined the zero-point noise and calculated it for different analytes, including those used in forensic analysis and organic pollutants. The zero-point noise level is highest for shortest-wavelength plasmons and decreases towards long-range plasmons. It may be tailored through a convenient design of the metamaterial structure. Since noise spectral power is proportional to the nonlinearity of the analyte species present, we considered the possibility to use zero-point noise as an auxiliary tool for identification of targeted nonlinear samples. We believe that our investigation could be of importance in homeland defence, forensics, biomedicine, etc

Super Unit Cells in Aperture-Based Metamaterials

An important class of electromagnetic metamaterials are aperture-based metasurfaces. Examples include extraordinary optical transmission arrays and double fishnets with negative refractive index. We analyze a generalization of such metamaterials where a simple aperture is now replaced by a compound object formed by superposition of two or more primitive objects (e.g., rectangles, circles, and ellipses). Thus obtained "super unit cell" shows far richer behavior than the subobjects that comprise it. We show that nonlocalities introduced by overlapping simple subobjects can be used to produce large deviations of spectral dispersion even for small additive modifications of the basic geometry. Technologically, some super cellsmay be fabricated by simple spatial shifting of the existing photolithographic masks. In our investigation we applied analytical calculations and ab initio finite element modeling to prove the possibility to tailor the dispersion including resonances for plasmonic nanocomposites by adjusting the local geometry and exploiting localized interactions at a subwavelength level. Any desired form could be defined using simple primitive objects, making the situation a geometrical analog of the case of series expansion of a function. Thus an additional degree of tunability of metamaterials is obtained. The obtained designer structures can be applied in different fields like waveguiding and sensing

Experimental research of the tube absorbers of kinetic energy during collision

Razvoj elemenata za apsorbciju energije sudara je sastavni deo pasivne zaštite putničkih vagona. Pasivna zaštita ima zadatak da posledice sudara svede na minimum. Apsorber prikazan u radu napravljen je od standardne bešavne cevi u kvalitetu P235T1 i konusnog prstena kvaliteta C45E. Predstavljeno rešenje se zasniva na korišćenju specijalnih elemenata koji apsorbuju određenu količinu kinetičke energije sudara putem kontrolisane plastične deformacije, čime se značajno smanjuje deo energije koji se prenosi na noseću strukturu vozila. Pri sudaru dolazi do sabijanja-provlačenja cevi kroz konusni prsten. Težište rada je na eksperimentalnim istraživanjima radi određivanja stvarnih karakteristika apsorbera ovog tipa. Na osnovu analize dobijenih rezultata ispitivanja, predloženo je konačno konstruktivno rešenje apsorbera, kao elementa buduće konstrukcije čeonog dela postolja vagona.Development of collision energy absorbing elements is a constituent part of passive protection of passenger coaches. The target of passive protection is to minimize the collision consequences. The absorber, described in this paper, is constructed from a standard seamless tube of the quality P235T1 and conical ring of the quality C45E. The solution presented is based on the application of special elements that absorb a certain amount of collision kinetic energy by means of controlled plastic deformation, significantly decreasing the part of the energy which is transferred to the vehicle bearing structure. The tube is compressed - pushed through the conical ring in collision. The paper focuses on the quasi-static and dynamics experimental research. Based on the analysis of the results obtained in the research, a final design of the absorber is suggested as a part of the future front part of vehicle bearing structure

Experimental and numerical determination of tube collision energy absorbers characteristics

Razvoj apsorbera energije sudara je jedna od neophodnih mera pasivne zaštite putničkih vagona. Uloga pasivne zaštite je da posledice sudara svede na najmanju moguću meru. Apsorber razvijan u ovom radu sastoji se od čeličnih bešavnih cevi u kvalitetu P235T1 i konusne čaure napravljene od čelika za poboljšanje u kvalitetu C45E. Tokom sudara provlačenjem cevi kroz konusnu čauru dolazi do redukcije - smanjenja prečnika cevi pri čemu se troši energija. U radu su analizirani rezultati dobijeni numeričkim simulacijama i dinamičkim ispitivanjima cevnih apsorbera kinetičke energije sudara putničkih vagona. Glavni cilj rada je uspostavljanje korelacije rezultata dobijenih numeričkim simulacijama i eksperimentalnim istraživanjima. Korišćenjem karakterističnih parametara dobijenih tokom kvazi-statičkih, dinamičkih ispitivanja i numeričkih simulacija, definisane su vrednosti ključnih parametara koje se mogu koristiti za buduća ispitivanja cevnih apsorbera ovog tipa pri brzinama većim od 20 km/h. Numeričke simulacije se mogu koristiti u fazi razvoja apsorpcionih elemenata dok je za konačnu ocenu prototipa neophodno uraditi dinamička ispitivanja.Development of collision energy absorbers is one of the necessary measures for passive safety of passenger coaches. The purpose of passive safety is to minimize the collision consequences for passengers. The collision absorber developed in this work consisted of a low carbon seamless steel tube and conical bush fabricated from quench and tempered carbon steel. During collision, the seamless tube is compressed into a bush with a reduced diameter. In this paper, the analysis of results is obtained by numerical simulations and dynamic investigation of tube absorbers of kinetic collision energy of passenger coaches. The research focuses on correlations between numerical and dynamic test results. Using the characteristic parameters obtained by the dynamic tests and numerical simulations, values for key numerical parameters have been defined, which can be used for further investigations of tube shrinking absorber. Numerical simulations should be used in the developing phase of a prototype, while for the final verification it is necessary to do dynamic (impact) test

Experimental and numerical analysis of the characteristics of combined collision energy absorbers

Predmet ovog rada su eksperimentalna istraživanja i numeričke simulacije kombinovanih apsorbera kinetičke energije sudara. Ovi elementi su deo pasivnih mera zaštite šinskih vozila. Ovaj tip apsorbera radi na principu kontrolisane deformacije koristeći proces sužavanja i gužvanja cevi. Ideja da se koriste ova dva procesa u paralelnom modu imala je za cilj da se, putem kontrolisanih deformacija uz ograničene dimenzije apsorbera, apsorbuje što je moguće veća količina kinetičke energije sudara. Apsorpcija energije se ostvaruje putem elasto-plastičnih deformacija cevi i trenjem između cevi i konusne čaure. Korišćenjem kombinovanog metoda, tokom sudara, apsorpcija energije počinje u cevi koja se sužava provlačenjem kroz konusnu čauru. Simultani proces gužvanja spoljne cevi počinje posle definisanog hoda, pa se obe cevi deformišu na preostalom hodu u paralelnom modu. Na ovaj način sila postepeno raste bez nepoželjnih pikova tokom čitavog hoda, što rezultira znatno većom količinom apsorbovane energije. Eksperimentalna istraživanja kombinovanog apsorbera realizovana su u laboratorijskim uslovima. Tokom eksperimentalnih istraživanja mereni su sila i hod. Numeričke simulacije su korišćene za proveru apsorpcione moći apsorpcionih elemenata pre eksperimentalnih istraživanja. Po završetku numeričkih simulacija i kvazi-statičkih testova, snimljeni podaci su analizirani i formirani su dijagrami sile u funkciji od hoda. Rezultati proračuna korišćenjem metode konačnih elemenata i rezultati eksperimentalnih istraživanja su u dobroj korelaciji.The subject of this paper are experimental researches and numerical simulations of combined collision energy absorber. These elements are parts of passive safety measures of railway vehicles. This type of absorber works on the principle of controlled deformation using shrinking and folding process of the tubes. The idea was to use process of shrinking and folding tubes in a parallel mode to absorb as much collision kinetic energy as possible by controlled deformation, with limited dimensions of absorber. Energy absorption was achieved by elastic-plastic deformations of the tubes and friction between the tube and the cone bush. Using combined method, during the collision, energy absorption starts in the tube which is compressed into cone bush. After pre-defined stroke in the process of energy absorption the simultaneous process of folding of the outer tube starts, so both tubes deform in parallel mode during the rest of the stroke. In this way the force gradually increases without undesirable peaks during the entire stroke, resulting significant bigger amount of absorbed energy. Experimental investigations of combined absorber were realized in laboratory conditions. During experimental investigations the stroke and force were measured. The numerical simulations were used for checking the absorption power of absorption elements before the experimental researches. After the numerical simulations and quasi-static tests were completed, recorded data were analyzed and force versus stroke diagrams were made. Results of calculation using FEM and results obtained experimentally are in good correlation

Experimental and numerical analysis of the characteristics of combined collision energy absorbers

Predmet ovog rada su eksperimentalna istraživanja i numeričke simulacije kombinovanih apsorbera kinetičke energije sudara. Ovi elementi su deo pasivnih mera zaštite šinskih vozila. Ovaj tip apsorbera radi na principu kontrolisane deformacije koristeći proces sužavanja i gužvanja cevi. Ideja da se koriste ova dva procesa u paralelnom modu imala je za cilj da se, putem kontrolisanih deformacija uz ograničene dimenzije apsorbera, apsorbuje što je moguće veća količina kinetičke energije sudara. Apsorpcija energije se ostvaruje putem elasto-plastičnih deformacija cevi i trenjem između cevi i konusne čaure. Korišćenjem kombinovanog metoda, tokom sudara, apsorpcija energije počinje u cevi koja se sužava provlačenjem kroz konusnu čauru. Simultani proces gužvanja spoljne cevi počinje posle definisanog hoda, pa se obe cevi deformišu na preostalom hodu u paralelnom modu. Na ovaj način sila postepeno raste bez nepoželjnih pikova tokom čitavog hoda, što rezultira znatno većom količinom apsorbovane energije. Eksperimentalna istraživanja kombinovanog apsorbera realizovana su u laboratorijskim uslovima. Tokom eksperimentalnih istraživanja mereni su sila i hod. Numeričke simulacije su korišćene za proveru apsorpcione moći apsorpcionih elemenata pre eksperimentalnih istraživanja. Po završetku numeričkih simulacija i kvazi-statičkih testova, snimljeni podaci su analizirani i formirani su dijagrami sile u funkciji od hoda. Rezultati proračuna korišćenjem metode konačnih elemenata i rezultati eksperimentalnih istraživanja su u dobroj korelaciji.The subject of this paper are experimental researches and numerical simulations of combined collision energy absorber. These elements are parts of passive safety measures of railway vehicles. This type of absorber works on the principle of controlled deformation using shrinking and folding process of the tubes. The idea was to use process of shrinking and folding tubes in a parallel mode to absorb as much collision kinetic energy as possible by controlled deformation, with limited dimensions of absorber. Energy absorption was achieved by elastic-plastic deformations of the tubes and friction between the tube and the cone bush. Using combined method, during the collision, energy absorption starts in the tube which is compressed into cone bush. After pre-defined stroke in the process of energy absorption the simultaneous process of folding of the outer tube starts, so both tubes deform in parallel mode during the rest of the stroke. In this way the force gradually increases without undesirable peaks during the entire stroke, resulting significant bigger amount of absorbed energy. Experimental investigations of combined absorber were realized in laboratory conditions. During experimental investigations the stroke and force were measured. The numerical simulations were used for checking the absorption power of absorption elements before the experimental researches. After the numerical simulations and quasi-static tests were completed, recorded data were analyzed and force versus stroke diagrams were made. Results of calculation using FEM and results obtained experimentally are in good correlation

Experimental research of the tube absorbers of kinetic energy during collision

Razvoj elemenata za apsorbciju energije sudara je sastavni deo pasivne zaštite putničkih vagona. Pasivna zaštita ima zadatak da posledice sudara svede na minimum. Apsorber prikazan u radu napravljen je od standardne bešavne cevi u kvalitetu P235T1 i konusnog prstena kvaliteta C45E. Predstavljeno rešenje se zasniva na korišćenju specijalnih elemenata koji apsorbuju određenu količinu kinetičke energije sudara putem kontrolisane plastične deformacije, čime se značajno smanjuje deo energije koji se prenosi na noseću strukturu vozila. Pri sudaru dolazi do sabijanja-provlačenja cevi kroz konusni prsten. Težište rada je na eksperimentalnim istraživanjima radi određivanja stvarnih karakteristika apsorbera ovog tipa. Na osnovu analize dobijenih rezultata ispitivanja, predloženo je konačno konstruktivno rešenje apsorbera, kao elementa buduće konstrukcije čeonog dela postolja vagona.Development of collision energy absorbing elements is a constituent part of passive protection of passenger coaches. The target of passive protection is to minimize the collision consequences. The absorber, described in this paper, is constructed from a standard seamless tube of the quality P235T1 and conical ring of the quality C45E. The solution presented is based on the application of special elements that absorb a certain amount of collision kinetic energy by means of controlled plastic deformation, significantly decreasing the part of the energy which is transferred to the vehicle bearing structure. The tube is compressed - pushed through the conical ring in collision. The paper focuses on the quasi-static and dynamics experimental research. Based on the analysis of the results obtained in the research, a final design of the absorber is suggested as a part of the future front part of vehicle bearing structure