A doença de Fabry (DF) é um erro inato do catabolismo de glicoesfingolipídeos de herança ligada ao cromossomo X decorrente de uma atividade deficiente da enzima lisossômica C-galactosidase A. Os pacientes apresentam como principais achados angioqueratomas na pele e acroparestesias e geralmente vão a óbito na idade adulta por falência renal e acidente vascular cerebral. Como conseqüência da deficiência enzimática, os substratos (principalmente a globotriaosilceramida – Gb3) acumulam-se em fluidos corporais e lisossomas de diversos tipos celulares do organismo. Desde 2001, a terapia disponível para a DF é a Terapia de Reposição Enzimática (TRE). Antes disso, o tratamento era apenas para os sintomas. Algumas hipóteses para a fisiopatologia da DF estão intimamente ligadas à produção de espécies reativas e inflamação, porém até este momento não haviam estudos in vivo sobre esse tema. Então, o objetivo deste estudo foi investigar parâmetros de estresse oxidativo, citocinas próinflamatórias e Gb3 em pacientes com DF em tratamento com TRE e, finalmente, estabelecer uma possível relação entre eles. Analisamos amostras de sangue e urina de pacientes com DF sob TRE (n=14) e controles saudáveis pareados por idade (n=14). Os pacientes apresentaram níveis diminuídos de defesas antioxidantes, medidas através de glutationa (GSH), atividade da glutationa peroxidase (GPx) e aumento da razão superóxido dismutase/catase (SOD/CAT) em eritrócitos. Em relação ao dano a biomoléculas (lipídeos e proteínas), verificamos nos pacientes aumento de malondialdeído (MDA) e grupamentos carbonilas proteicos no plasma e de di-tirosina (di-Tyr) na urina. As citocinas próinflamatórias IL-6 e TNF-C também mostraram-se aumentadas no plasma dos pacientes. O Gb3 na urina apresentou correlação significativa direta com os níveis plasmáticos de IL-6, grupamentos carbonilas e MDA. IL-6 mostrou-se direta e significativamente correlacionada com di-Tyr e inversamente correlacionada com a atividade da GPx. Esses dados sugerem que os estados próinflamatório e pró-oxidante ocorrem, estão correlacionados e parecem ser induzidos pelo Gb3 em pacientes com DF em tratamento com TRE. / Fabry disease (FD) is an X-linked inborn error of glycosphingolipid catabolism due to deficient activity of C-galactosidase A. Patients present as main findings angiokeratomas in skin and acroparesthesias and usually die in adult age of renal failure and stroke. As a consequence of the enzyme deficiency, the substrates (mainly globotriaosylceramide - Gb3) accumulate in body fluids and lysosomes of many cell types of organism. Since 2001, the available therapy for FD is the Enzyme Replacemente Therapy (ERT). Before that, treatment was just for the symptoms. Some pathophysiology hypotheses are intimately linked to reactive species production and inflammation, but until this moment there were no in vivo studies about it. Hence, the aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokines and Gb3 in patients with FD under treatment with ERT and, finally, to establish a possible relation between them. We analyzed blood and urine samples of Fabry patients under ERT (n=14) and healthy age-matched controls (n=14). Patients presented decreased levels of antioxidant defenses, assessed by glutathione (GSH), glutathione peroxidase (GPx) activity and increased superoxide dismutase/catalase (SOD/CAT) ratio in erythrocytes. Concerning to the damage to biomolecules (lipids and proteins), we verified in patients increase of malondialdehyde (MDA) and protein carbonyl groups in plasma and of dityrosine (di-Tyr) in urine. The pro-inflammatory cytokines IL-6 and TNF-C were also increased in plasma from patients. Urinary Gb3 presented significant direct correlation with the plasma levels of IL-6, carbonyl groups and MDA. IL-6 was directly and significantly correlated with di-Tyr and inversely correlated with GPx activity. This data suggest that a pro-inflammatory and pro-oxidant state occur, are correlated and seem to be induced by Gb3 in Fabry patients under ERT treatment.

A doença de Fabry (DF) é um erro inato do catabolismo de glicoesfingolipídeos de herança ligada ao cromossomo X decorrente de uma atividade deficiente da enzima lisossômica C-galactosidase A. Os pacientes apresentam como principais achados angioqueratomas na pele e acroparestesias e geralmente vão a óbito na idade adulta por falência renal e acidente vascular cerebral. Como conseqüência da deficiência enzimática, os substratos (principalmente a globotriaosilceramida – Gb3) acumulam-se em fluidos corporais e lisossomas de diversos tipos celulares do organismo. Desde 2001, a terapia disponível para a DF é a Terapia de Reposição Enzimática (TRE). Antes disso, o tratamento era apenas para os sintomas. Algumas hipóteses para a fisiopatologia da DF estão intimamente ligadas à produção de espécies reativas e inflamação, porém até este momento não haviam estudos in vivo sobre esse tema. Então, o objetivo deste estudo foi investigar parâmetros de estresse oxidativo, citocinas próinflamatórias e Gb3 em pacientes com DF em tratamento com TRE e, finalmente, estabelecer uma possível relação entre eles. Analisamos amostras de sangue e urina de pacientes com DF sob TRE (n=14) e controles saudáveis pareados por idade (n=14). Os pacientes apresentaram níveis diminuídos de defesas antioxidantes, medidas através de glutationa (GSH), atividade da glutationa peroxidase (GPx) e aumento da razão superóxido dismutase/catase (SOD/CAT) em eritrócitos. Em relação ao dano a biomoléculas (lipídeos e proteínas), verificamos nos pacientes aumento de malondialdeído (MDA) e grupamentos carbonilas proteicos no plasma e de di-tirosina (di-Tyr) na urina. As citocinas próinflamatórias IL-6 e TNF-C também mostraram-se aumentadas no plasma dos pacientes. O Gb3 na urina apresentou correlação significativa direta com os níveis plasmáticos de IL-6, grupamentos carbonilas e MDA. IL-6 mostrou-se direta e significativamente correlacionada com di-Tyr e inversamente correlacionada com a atividade da GPx. Esses dados sugerem que os estados próinflamatório e pró-oxidante ocorrem, estão correlacionados e parecem ser induzidos pelo Gb3 em pacientes com DF em tratamento com TRE. / Fabry disease (FD) is an X-linked inborn error of glycosphingolipid catabolism due to deficient activity of C-galactosidase A. Patients present as main findings angiokeratomas in skin and acroparesthesias and usually die in adult age of renal failure and stroke. As a consequence of the enzyme deficiency, the substrates (mainly globotriaosylceramide - Gb3) accumulate in body fluids and lysosomes of many cell types of organism. Since 2001, the available therapy for FD is the Enzyme Replacemente Therapy (ERT). Before that, treatment was just for the symptoms. Some pathophysiology hypotheses are intimately linked to reactive species production and inflammation, but until this moment there were no in vivo studies about it. Hence, the aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokines and Gb3 in patients with FD under treatment with ERT and, finally, to establish a possible relation between them. We analyzed blood and urine samples of Fabry patients under ERT (n=14) and healthy age-matched controls (n=14). Patients presented decreased levels of antioxidant defenses, assessed by glutathione (GSH), glutathione peroxidase (GPx) activity and increased superoxide dismutase/catalase (SOD/CAT) ratio in erythrocytes. Concerning to the damage to biomolecules (lipids and proteins), we verified in patients increase of malondialdehyde (MDA) and protein carbonyl groups in plasma and of dityrosine (di-Tyr) in urine. The pro-inflammatory cytokines IL-6 and TNF-C were also increased in plasma from patients. Urinary Gb3 presented significant direct correlation with the plasma levels of IL-6, carbonyl groups and MDA. IL-6 was directly and significantly correlated with di-Tyr and inversely correlated with GPx activity. This data suggest that a pro-inflammatory and pro-oxidant state occur, are correlated and seem to be induced by Gb3 in Fabry patients under ERT treatment.

A doença de Fabry (DF) é um erro inato do catabolismo de glicoesfingolipídeos de herança ligada ao cromossomo X decorrente de uma atividade deficiente da enzima lisossômica C-galactosidase A. Os pacientes apresentam como principais achados angioqueratomas na pele e acroparestesias e geralmente vão a óbito na idade adulta por falência renal e acidente vascular cerebral. Como conseqüência da deficiência enzimática, os substratos (principalmente a globotriaosilceramida – Gb3) acumulam-se em fluidos corporais e lisossomas de diversos tipos celulares do organismo. Desde 2001, a terapia disponível para a DF é a Terapia de Reposição Enzimática (TRE). Antes disso, o tratamento era apenas para os sintomas. Algumas hipóteses para a fisiopatologia da DF estão intimamente ligadas à produção de espécies reativas e inflamação, porém até este momento não haviam estudos in vivo sobre esse tema. Então, o objetivo deste estudo foi investigar parâmetros de estresse oxidativo, citocinas próinflamatórias e Gb3 em pacientes com DF em tratamento com TRE e, finalmente, estabelecer uma possível relação entre eles. Analisamos amostras de sangue e urina de pacientes com DF sob TRE (n=14) e controles saudáveis pareados por idade (n=14). Os pacientes apresentaram níveis diminuídos de defesas antioxidantes, medidas através de glutationa (GSH), atividade da glutationa peroxidase (GPx) e aumento da razão superóxido dismutase/catase (SOD/CAT) em eritrócitos. Em relação ao dano a biomoléculas (lipídeos e proteínas), verificamos nos pacientes aumento de malondialdeído (MDA) e grupamentos carbonilas proteicos no plasma e de di-tirosina (di-Tyr) na urina. As citocinas próinflamatórias IL-6 e TNF-C também mostraram-se aumentadas no plasma dos pacientes. O Gb3 na urina apresentou correlação significativa direta com os níveis plasmáticos de IL-6, grupamentos carbonilas e MDA. IL-6 mostrou-se direta e significativamente correlacionada com di-Tyr e inversamente correlacionada com a atividade da GPx. Esses dados sugerem que os estados próinflamatório e pró-oxidante ocorrem, estão correlacionados e parecem ser induzidos pelo Gb3 em pacientes com DF em tratamento com TRE. / Fabry disease (FD) is an X-linked inborn error of glycosphingolipid catabolism due to deficient activity of C-galactosidase A. Patients present as main findings angiokeratomas in skin and acroparesthesias and usually die in adult age of renal failure and stroke. As a consequence of the enzyme deficiency, the substrates (mainly globotriaosylceramide - Gb3) accumulate in body fluids and lysosomes of many cell types of organism. Since 2001, the available therapy for FD is the Enzyme Replacemente Therapy (ERT). Before that, treatment was just for the symptoms. Some pathophysiology hypotheses are intimately linked to reactive species production and inflammation, but until this moment there were no in vivo studies about it. Hence, the aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokines and Gb3 in patients with FD under treatment with ERT and, finally, to establish a possible relation between them. We analyzed blood and urine samples of Fabry patients under ERT (n=14) and healthy age-matched controls (n=14). Patients presented decreased levels of antioxidant defenses, assessed by glutathione (GSH), glutathione peroxidase (GPx) activity and increased superoxide dismutase/catalase (SOD/CAT) ratio in erythrocytes. Concerning to the damage to biomolecules (lipids and proteins), we verified in patients increase of malondialdehyde (MDA) and protein carbonyl groups in plasma and of dityrosine (di-Tyr) in urine. The pro-inflammatory cytokines IL-6 and TNF-C were also increased in plasma from patients. Urinary Gb3 presented significant direct correlation with the plasma levels of IL-6, carbonyl groups and MDA. IL-6 was directly and significantly correlated with di-Tyr and inversely correlated with GPx activity. This data suggest that a pro-inflammatory and pro-oxidant state occur, are correlated and seem to be induced by Gb3 in Fabry patients under ERT treatment.

Les milieux Kerr soumis à des faisceaux optiques contrapropageants provenant, soit d'une cavité Pérot-Fabry plan-plan ou d'une boucle de rétro-action, ont été très étudiés pour la génération de structures transverses. De nombreux développements théoriques dans la configuration de la cavité ont prédit l'existence de structures localisées (solitons). Cependant aucune mise en évidence expérimentale de ces structures n'a été réalisée à ce jour. Dans la configuration de la boucle de rétro-action optique, les régimes fortement non linéaires présentent des structures rares et intenses, très localisées aussi bien spatialement que temporellement. C'est dans ce cadre que nous nous intéressons expérimentalement à la structuration localisée de la lumière dans ces deux systèmes. La première partie de cette thèse est consacrée à la mise en évidence expérimentale de solitons spatiaux dans une cavité Pérot-Fabry plan-plan Kerr à diffraction positive. Ensuite, nous étudions cette cavité quand elle est soumise à de la diffraction négative. Des parois de domaines propagatives sont alors observées. Celles-ci sont bloquées par le forçage spatial lié à l'inhomogénéité du profil de pompage optique gaussien qui donne lieu à une localisation de la lumière. Nous étudions succinctement le cas limite d'une cavité sans diffraction dans laquelle les parois de domaines survivent. Pour finir nous effectuons une étude du régime très fortement non linéaire dans le dispositif de rétro-action optique grâce à une approche statistique. Nous observons l'apparition de structures localisées scélérates associées à l'émission d'un supercontinuum spectral spatial. / Kerr media subject to counterpropagating optical beams in a plan-plan Pérot-Fabry cavity or optical feedback have been deeply studied for tranverse pattern generation. Many theoretical developments in the cavity configuration predict the existence of localized structures (solitons). However, no experimental evidence of these structures have been giben up to now. In the feedback configuration, the highly nonlinear regimes present rare and intense localized structures in space and in time. In This this framework, we are interested in studying experimentaly the localization of light in the both previous systems. The first part of this thesis is devoted to the experimental evidence of spatial solitons in a Pérot-Fabry Kerr plan-plan cavity with positive diffraction. Then we study this cavity submitted to negative diffraction. Propagative domain walls are observed. They are pinned by the spatial forcing coming from the inhomogeneous gaussian optical pumping profile that induces light localization. We study briefly the case of cavity without diffraction in which domain walls persist. We findly perform a study of highly nonlinear regimes in the optical feedback device using a statistical approach. We observe the emergence of rogue localized structures associated with the emission of a spatial spectral supercontinuum.

La maladie de Fabry est une maladie de surcharge lysosomale liée au chromosome X. Elle est causée par une mutation au niveau du gène GLA qui provoque un déficit de l’enzyme α-galactosidase A. Elle entraîne une accumulation de glycosphingolipides tels le globotriaosylcéramide (Gb3), le globotriaosylsphingosine (lyso-Gb3) et galabiosylcéramide (Ga2) ainsi que leurs isoformes/analogues respectifs au niveau des tissus et des liquides biologiques des patients. Les symptômes peuvent se présenter de manière très variable soit par de l’acroparesthésie, des troubles ophtalmologiques, des angiokératomes, des troubles cardiaques, rénaux ou encore neurologiques. Les connaissances au niveau physiopathologique de la maladie de Fabry sont à ce jour, toujours déficientes. Les biomarqueurs analysés ne permettent pas de prédire la sévérité et la progression de la maladie. Afin d’apporter des connaissances plus approfondies à ce niveau, l’objectif principal de cette étude était d’analyser les biomarqueurs au niveau cellulaire pour des patients atteints de la maladie. Les objectifs secondaires étaient: 1) de développer et de valider une méthode en spectrométrie de masse en tandem pour la quantification relative et simultanée de certains biomarqueurs susmentionnés dans les leucocytes, les lymphocytes B et les monocytes de patients Fabry et contrôles sains; 2) d’évaluer les biomarqueurs dans le total des leucocytes, les lymphocytes B, les monocytes, le plasma et l’urine chez les patients Fabry et les contrôles sains appariés selon le sexe et l’âge; et 3) d’établir des corrélations entre la quantité relative de ces biomarqueurs et le génotype des patients traités et non traités. Les résultats de cette étude démontrent qu’il n’y a pas de changements significatifs dans la distribution des groupes d’isoformes/analogues du Gb3 selon le type cellulaire pour les patients et les contrôles. La découverte d’isoformes/analogues méthylés du Gb3 suggère un processus de méthylation qui se produit directement au niveau des cellules sanguines et particulièrement pour les lymphocytes B et les monocytes. Des corrélations face à la quantité de biomarqueurs et le génotype ont été établies. Ces résultats pourraient permettre une meilleure compréhension des processus biochimiques reliés à l’accumulation du Gb3 dans les cellules sanguines.

Techniques for adapting metamaterials for the improvement of RF energy harvesting and infrared photodetection are demonstrated using experimental and computer simulation methods. Two methods for RF energy harvesting are experimentally demonstrated and supported by computer simulation. In the first method, a metamaterial perfect absorber (MPA) is made into a rectenna capable of harvesting RF energy and delivering power to a load by soldering Schottky diodes onto connected split ring resonator (SRR) structures composing the planar metasurface of the perfect absorber. The metamaterial rectenna is accompanied by a ground plane placed parallel to it, which forms a Fabry-Perot cavity between the metasurface and the ground plane. The Fabry-Perot cavity stores energy in the form of standing waves which is transferred to the SRR structures of the metasurface as AC currents that are rectified by the diodes to create DC power. This type of design enables highly efficient energy harvesting for low input power, creates a large antenna capture area, and uses elements with small electrical size, such that 100 uW of power (enough to operate simple devices) can be captured at ambient intensities ~ 1 - 2 uW/cm2. Two designs using this method are presented, one that operates for linear polarizations at 0.9 GHz and a smaller polarization-independent design that operates around 1.5 GHz. In the second method, the energy stored in the standing waves of an MPA Fabry-Perot cavity is instead harvested by placing a separate energy harvesting antenna within the cavity. The cavity shapes and enhances the incident electric field, and then the separate energy harvesting antenna is designed to be inserted into the cavity so that its shape and/or radiation pattern matches the electric field lines within the cavity and maximally extracts the stored energy. This method allows for great customization of antenna design parameters, such as operating frequency, polarization dependence, and directionality, by swapping out different metasurface and antenna designs. Using this method, the amount of power harvested by a simple dipole rectenna placed within a cavity is improved by a factor of 18 as compared to what it would harvest by itself at an ambient intensity of 35 nW/cm2. Lastly, the addition of plasmonic structures to DWELL (quantum dot-in-a-well) infrared photodetectors is investigated by computer simulation. DWELL photodetectors have the potential to one day replace standard mercury cadmium telluride detectors by being cheaper alternatives with a higher operating temperature. The inclusion of gold plasmonic structure arrays into DWELL detectors enables excitation of surface plasmon polariton modes that increase the responsivity of the detector to incident infrared radiation. The peak responsivity of a DWELL detector is demonstrated to improve by a factor of 8 for a 1 um thick layer of plasmonic structures and by a factor of 15 for a 2 um thick layer. These works are steps forward in making RF energy harvesting practically useful and for improving infrared photodetector performance.

There is an increasing need for tuneable spectrally pure semiconductor laser sources as well as broadband and polarization insensitive semiconductor optical amplifiers based on the InGaASP/InP material system, to be monolithically integrated with other active and passive components in a photonic integrated circuit. This thesis aims to contribute to finding a solution through modelling, experimental characterization and design improvements. In this thesis we have analyzed laterally-coupled distributed feedback (LC-DFB) lasers. These lasers have the gratings etched directly out of the ridge sidewalls thus lowering the cost associated with the re-growth process required if the gratings were otherwise embedded above the active region. The performance characteristics are analyzed for the LC-DFB lasers partitioned into 1-, 2-, and 3-, electrodes with individual bias control at various operating temperatures. The laser exhibits a stable single mode emission at 1560 nm with a current tuning rate of ~14 pm/mA for a tuning of 2.25 nm. The side modes are highly suppressed with a maximum side-mode suppression ratio of 58 dB. The light-current characteristics show a minimum 40 mA threshold current, and power saturation occurring at higher injection currents. The linewidth characteristics show a minimum Lorentzian linewidth of 210 kHz under free-running and further linewidth reduction under feedback operation. The multi-electrode LC-DFB laser devices under appropriate and selective driving conditions exhibit a flat frequency modulation response from 0 to above 300 MHz. The multi-electrode configuration can thus be further exploited for certain requirements. Simulation results and design improvements are also presented. The experimental characterization of semiconductor optical amplifier (SOA) and Fabry-Perot (FP) laser operating in the E-band are also presented. For the SOA, the linear vertical and horizontal states of polarization corresponding to the transverse electric (TE) and transverse magnetic (TM) modes were considered. For various input power and bias, performance characteristics shows a peak gain of 21 dBm at 1360 nm, gain bandwidth of 60 nm and polarization sensitivity of under 3 dB obtained for the entire wavelength range analyzed from 1340 to 1440 nm. The analysis presented in this thesis show good results with room for improvement in future designs.

Fabry disease is an inherited X-linked recessive disorder caused by mutations in the galactosidase alpha (GLA) gene, leading to deficiencies in α-galactosidase A (α-GAL) enzyme production. α-GAL, a lysosomal glycosidase, catalyzes the removal of a terminal α-galactose; however, loss of α-GAL activity leads to accumulation of globotriaosylceramide (an endogenous substrate) and the eventual onset of the disease. Approved treatments for Fabry disease include enzyme replacement therapy and pharmacological chaperone therapy. In the latter treatment, 1-deoxygalactonojirimycin (DGJ), a pharmacological chaperone, is administered to Fabry disease patients, leading to increased enzymatic activity. The DGJ iminosugar acts as a competitive inhibitor of α-GAL, and upon addition at sub-inhibitory concentrations, the α-GAL activity in the cell increases. At pH 7.5, the DGJ binds and stabilizes both wild type and mutant α-GAL and can thus drive the folding of the α-GAL protein (Guce 2011). DGJ has been clinically approved to treat a subset of the more than 900 known mutations in the GLA gene. These approvals come from the chaperone activity data published by Amicus Therapeutics (Benjamin 2017). However, these assays cost money, time, and effort to perform, and novel mutations are discovered annually. Using molecular dynamics energy calculations in the Schrödinger software package, we developed a model to predict successful chaperoning of the mutants. Overall, the results are directly applicable to Fabry disease, but could also be applied to the much larger family of protein folding diseases, including Alzheimer's, Parkinson's and Huntington's diseases.

Diploma thesis deals with the construction of a moder semiconductor optical amplifier SOA. In the first chapter optical comunication and the use of optical amplifiers is described. In the next chapter some types of optical fibers, their chemical composition and properties are described in detail. The third chapter overviews optical amplifiers, their use today, describes their advantages and disadvantages and their proper use in optical comunications. The fourth chapter describes the solution of the objective, the right layout of separate blocks and connections used in measurements. Fifth chapter describes used components, describes their basic parameters and proper use in circuit. The last chapter evaluates outputs of measurements and their impact on the objective.

This thesis focuses on the theory, fabrication, and characterization of 2-port surface acoustic wave (SAW) resonators, as well as the application of their Fabry-Pérot resonance modes for strain sensing. The thesis includes three articles. In the first article, a fabrication method for high frequency SAW devices using traditional UV photolithography equipment is developed. It is well known that SAW sensors become more sensitive at higher frequencies but realizing high frequency devices requires small features which challenge existing photolithography methods. The proposed process is a modified version of a previously reported tri-layer lift-off photolithography process intended for Si or SiO2 substrates which allows for compatibility with materials that are piezoelectric and pyroelectric, often used as the substrate in SAW devices. The process uses a lithographic tri-layer consisting of layers of lift-off resist (LOR) on the bottom, back anti-reflection coating (BARC) in the middle, and photoresist (PR) on top, improving resolution by a factor of two over traditional lift-off photolithography techniques. We demonstrate the fabrication of a SAW device with an interdigital transducer (IDT) pitch of 4 μm (minimum feature size of 1 μm) on 128o Y-X cut lithium niobate, whose operating frequency is measured as 994.5 MHz. The 2-Port SAW devices that are used in subsequent chapters are fabricated using this process. The second article proposes a method of analyzing acoustic Fabry-Pérot spectra, by analogy with optical cavities, to determine key SAW parameters. In our experiment, 2-port SAW resonators, consisting of two interdigital transducers (IDTs) laterally separated by a free surface cavity length, are used to generate SAWs on 128o Y-X lithium niobate that are trapped between the two IDTs which also act as Bragg reflectors. Fabry-Pérot cavity peaks can be observed through the electrical S11 (reflection) spectrum measured on one IDT, hence a 2-Port resonator is equivalent to an acoustic Fabry-Pérot cavity/resonator. Measurements of the free spectral range and linewidths are then fitted to linear models to obtain the free surface velocity and attenuation of SAW waves, as well as the reflection of interdigital transducers (IDTs), all of which are crucial design parameters. Our method of analyzing Fabry-Pérot spectra provides a convenient method for determining key characteristics of SAW waves and cavities. In the third article, a surface acoustic wave (SAW) strain sensor based on measuring acoustic Fabry-Pérot resonance peaks from a 2-port SAW resonator is demonstrated. A theoretical analysis is proposed to estimate the frequency sensitivity to strain of IDT and cavity resonances and to predict strain distributions in both the cavity and IDT regions of a 2-port SAW resonator bonded to a tapered cantilever beam. The frequency stability of cavity resonance peaks for fabricated 2-port SAW resonators of different cavity length are measured and analyzed to determine the cavity length which exhibits maximum frequency stability. A cross-correlation analysis technique is then introduced to improve the detection of the frequency shift of SAW resonances and enable multimode frequency shift detection. The measured frequency sensitivity to strain of the cavity resonances of a resonator 10 mm in length (operating frequency = 97.7 MHz) was found to be -103.2 ± 0.2 Hz/με while demonstrating excellent linearity (R2 = 0.9999). By considering a minimum signal to noise ratio (SNR) of 3 dB, the device exhibits a minimum strain resolution of only 234 nε.