Leiva Casemiro Oliveira

A Surface Plasmon Resonance Biochip That Operates Both in the Angular and Wavelength Interrogation Modes

This paper presents a surface plasmon resonance system based on a polymer prism chip. The device allows operation in both the angular and wavelength interrogation modes. The biochip design is discussed emphasizing the effect of the ambient temperature over the optical behavior. Birefringence effect, biochip polishing, and responsivity are also reported. The basic mathematical formulation for both operating modes is discussed, and morphological parameters are considered in the data analysis. Experimental sensorgrams obtained at both interrogation modes with the same polymer prism chip are presented and compared. The experimental sensorgrams obtained with assays providing reversible (phosphate buffered saline and hypochlorite solutions) and irreversible (neutravindin solution) bindings demonstrate the feasibility of the proposed design.

A surface plasmon resonance biosensor for angular and wavelength operation

This paper presents a surface plasmon resonance (SPR) sensor system based on a polymer prism chip. The device allows operation in both, the angular (AIM) and wavelength (WIM) interrogation modes. The basic mathematical formulation for both operating modes is discussed. Experimental sensogrammes obtained for both modes with the same polymer prism chip, are presented and compared. The results illustrate the feasibility of the proposed solution.

Surface plasmon resonance sensors : a materials guide to design and optimization

Introduction and background information.- Physical features of the surface plasmon polariton.- Physical features of surface plasmon resonance sensors.- Design features of surface plasmon resonance sensors.- Data extraction algorithms.- SPF-sensor properties of metal films and particles: free electron type metals.- Classical noble metals.- Noble transition metals of the platinum group.- Common transition metals.- Other common metals.- SPR active metal-type compounds.- Artificial metal-insulator multi-layer structures.- Conclusions.

Polymer-based surface plasmon resonance biochip: construction and experimental aspects

Abstract Introduction: Surface plasmon resonance biosensors are high sensitive analytical instruments that normally employ glass materials at the optical substrate layer. However, the use of polymer-based substrates is increasing in the last years due to favorable features, like: disposability, ease to construction and low-cost design. Review Recently, a polymer-based SPR biochip was proposed by using monochromatic and polychromatic input sources. Its construction and experimental considerations are detailed here. Experimental considerations and results, aspects from performance characteristics (resonance parameters, sensitivity and full width at half maximum – FWHM – calculations) are presented for hydrophilic and hydrophobic solutions. It is included also a brief description of the state of the art of polymer-based SPR biosensors.

Co-existence of Radiative and Non-Radiative Surface Plasmon Resonance Modes: Power Balance and Influence of Film Morphology

The power balance and conditions of co-existing radiative and non-radiative surface plasmon resonance modes have been exploited at the metal film-water interface. Angular (AIM) and wavelength (WIM) interrogation sensing conditions were applied. Polycrystalline, void-free metal layers were sputter deposited, composed of nm-sized crystalline grains. Radiative decay of propagating SPs, with emission into the upper half-space, has been observed for 50-nm thin Au and Ag-layers on BK7 glass and polymeric substrates in the AIM. The associated thermo-optical power budget has been quantified by calorimetric heat flow recordings, comprising a micro-fluidic set-up. For the Au-water interface, at least 88 ± 4 % of the SP-absorbed optical power dissipates by phonon excitation, followed by heat transfer from the metal film into the adjacent liquid phase. Only a small fraction of 2.4 ± 0.6 % dissipates through radiative emission. In presence of a rough interface and WIM conditions, radiative SP-decay persists by emission into the lower half-space. The luminescence type feature most likely originates from radiative excitation and decay of localized SPs, coupled to propagating SPs within the film volume. The spectral characteristic is in accord with earlier reported experimental observations by others and numerical simulations.

Implementation of a FPGA-based data acquisition and processing system for image sensors employed in SPR biosensing

Optical biosensors based on surface plasmon resonance (SPR) are powerful tools for detecting biomolecules. In this paper, a reconfigurable image acquisition and processing system for SPR sensors is presented. The system uses a FPGA device for acquiring and processing data from an image sensor to determine the angle at which the minimum reflectivity of the optical multilayer arrangement occurs. A frequency domain processing for smoothing the SPR signal is implemented in hardware. The system also incorporates a communication interface for sending processed and unprocessed data from the FPGA to a remote device and receiving settings regarding the data acquisition and data processing strategies.

Improved data extraction algorithm for biosensors utilizing surface plasmon resonance sensing

Biosensors based on surface plasmon resonance enable us to detect biochemical compounds by tracking the changes in the reflectivity of a multi-layered system excited with p-polarized light. In this paper, a method to detect the changes on resonance condition is proposed. The method is based on a single sinusoidal approximating function, presents low computational complexity, improved noise immunity, and provides a quite accurate measurement in a single signal processing step. Simulation and experimental results are presented to demonstrate the feasibility of the proposed solution as well as to show its superior noise immunity features when compared to well known resonance detection methods.

Leishmania spp. Detection Using a Surface Plasmon Resonance Biosensor

The detection of Leishmania spp. through a disposable surface plasmon resonance (SPR) biochip, using mono- and polychromatic sources, is presented here. A highly specific and sensitive-constrained synthetic peptide (LC2) derived from a mimotope of Leishmania chagasi antigen was immobilized on the sensing region using a simple protocol. ELISA- and PCR-confirmed negative and positive sera of Leishmania chagasi infected patients were used. Detection of positive IgG showed a fast response with good sensitivity and specificity for the proposed method.

Surface Plasmon Resonance Sensing Characteristics of Thin Aluminum Films in Aqueous Solution

Surface plasmon resonance (SPR) sensors, utilizing thin aluminum (Al) films, are reported. The sensor designs are based in the novel optical trapezoidal prism chip, made from either polymer or BK7 glass. Optimum Al-film thickness was determined to 20 ± 5 nm, and deposited by thermal e-beam evaporation and rf-magnetron sputtering. Upon contact to air, and in de-ionized aqueous solution, a self-limited surface oxide layer forms. Determined by ellipsometric recordings, its thickness grows from 4.6 ± 0.6 nm in air to 12.3 ± 2 nm in the wet interface. A single SP-resonance applies to the dry interface. Unusual spectral broadening, due to the presence of multiple resonances, is predicted and experimentally verified at the wet interface. The Al-oxide adlayer is beneficial in the angular interrogation, where the instrumental response approaches the one exhibited by the noble metals. Under wavelength interrogation conditions, the presence of the Al-oxide adlayer causes severe degradation of the sensor response. Both, angular and wavelength interrogation at the metal-aqueous solution interface were exploited experimentally and compared with theoretical predictions regarding the sensing features of gold (Au), copper (Cu), and silver (Ag) metal films as well. Limitations, cost aspects and alternative routes to overcome degradation and the loss of SPR-activity in the presence of ionic phosphate buffered saline aqueous solutions are outlined for Al-films.

Surface plasmon resonance features of corrugatec copper and gold films: Grating mode operation with wavelength interrogation

This work presents a theoretical and experimental results obtained with surface resonance sensors operating in the periodic grating mode. The spatial periodicity of the corrugated surface of the manufactured devices was set to 478 nm. Two types of metallic layers have been tested, one of 50 nm of gold and another of 100 nm of copper. The wavelength interrogation mode has been used and the beam of incident light was shined directly onto the metal layer. The characteristics of the transducer manufactured with the two corrugated surfaces have been explored in the Kretschmann configuration to determine the sensors responsivities. The obtained results confirmed the correctness of the proposed methodology and the feasibility of the proposed transducer designs. The sensor system was tested for situations where a change in the refractive index of the gas occurs due to the insertion of condensed water vapor. Both transducers are tested and results as sensibility and detection limit are presented and compared.