Label-free Optical Biosensing on a single chip.

Combining semiconductor technology with photonics, optics, and biochemistry leads to sensors with improved biomedical diagnostic capability

Characterization of the Performance of Optical Label-Free Biosensors

The field of optical label free biosensors has become a topic of interest during past years, with devices based on the detection of angular or wavelength shift of optical modes [1]. Common parameters to characterize their performance are the Limit of Detection (LOD, defined as the minimum change of refractive index upon the sensing surface that the device is able to detect, and also BioLOD, which represents the minimum amount of target analyte accurately resolved by the system; with units of concentration (common un its are p pm, ng/ml, or nM). LOD gives a first value to compare different biosensors, and is obtained both theoretically (using photonic calculation tools), and experimentally,covering the sensing area with fluids of different refractive indexes

Biosensing comparison between different geometries based on vertical submicron-structrures made of SU-8 resist

Previous work of the research group [1-4] demonstrated the viability of using periodic lattices of micro and nanopillars, called Bio-photonic sensing Cells (BICELLs), as an optical biosensor vertically characterized by visible spectrometry. Also we have studied theoretically [5] the performance of the BICELLs by 2D and 3D simulation in orde r to optimize the biosensing response. In this work we present the fabrication and biosensing comparison of different geometrical parameters on periodic lattices of pillars in order to discuss theoretical conclusions with these results. In this way, we have explored the biosensing response of other patter ns such as crosses, stars, cylinders, concentrical cylinders (Figure 1). Also we introduced a novel method to test the BICELLs in a cost-effective way by using an ultra-thin film of SU-8 spin-coated onto the patterns to reproduce the effect of a biofilm attached to the biosensor surface. Finally we have tested the biosensing response of the different geometries by the well-known Bovine Serum Albumin (BSA) immunoassay and compared with the theoretical simulation

Métodos no radiológicos para la valoración de las deformidades del raquis

La escoliosis y otras deformidades de la columna vertebral clásicamente son evaluadas para su diagnóstico y seguimiento mediante métodos radiográficos. El problema radica en los efectos nocivos de dosis repetidas de radiación ionizante en los pacientes en crecimiento, así como en el hecho de que el método de Cobb radiográfico no caracteriza por sí solo la deformidad vertebral, ya que depende de otros factores. Se presenta una revisión actualizada sobre nuevas técnicas no invasivas que han surgido a lo largo de los últimos veinte años para la evaluación de las deformidades vertebrales con el objetivo de complementar y sustituir, al menos parcialmente, los estudios radiográficosScoliosis and other deformities of spine are typically evaluated for diagnosis and follow-through with radiographic methods. The problem lies in the deleterious effects of repeated doses of ionizing radiation in patients on growth and in the fact that radiographic Cobb method can’t characterize alone the spinal deformity, as it depends on other factors. An update on new non-invasive techniques that have emerged over the last twenty years for the assessment of vertebral deformities in order to complement and, at least partially, to replace radiographic studies is presente

Optimization of Dengue immunoassay by label-free interferometric optical detection method

In this communication we report a direct immunoassay for detecting dengue virus by means of a label-free interferometric optical detection method. We also demonstrate how we can optimize this sensing response by adding a blocking step able to significantly enhance the optical sensing response. The blocking reagent used for this optimization is a dry milk diluted in phosphate buffered saline. The recognition curve of dengue virus over the proposed surface sensor demonstrates the capacity of this method to be applied in Point of Care technology

Towards In-Vitro Point of Care devices for in-situ diagnosis

Electronic and optoelectronic systems and subsystems play an important role to develop In-Vitro Diagnostics (IVDs) systems for healthcare, clinical, agro-food, environmental, pharmaceutical research or drug control, among many other applications. Although significant advantages have been described for label-free biosensing technology, still a limitednumber of compact devices for monitoring IVD in-situ have been already developed. In this paper a discussion about the current trends for developing Point-of-Care devices will be analyzed, as well as the future challenges for in-situ In-vitro diagnostic systems

Microfabrication processes for microfluidic devices on a single laser Workstation: direct writing lithography on SU-8, laser ablation on polymers and mask manufacturing

We demonstrate the capability of a laser micromachining workstation for cost-effective manufacturing of a variety of microfluidic devices, including SU-8 microchannels on silicon wafers and 3D complex structures made on polyimide Kapton® or poly carbonate (PC). The workstation combines a KrF excimer laser at 248 nm and a Nd3+:YVO4 DPSS with a frequency tripled at 355 nm with a lens magnification 10X, both lasers working at a pulsed regime with nanoseconds (ns) pulse duration. Workstation also includes a high-resolution motorized XYZ-tilt axis (~ 1 um / axis) and a Through The Lens (TTL) imaging system for a high accurate positioning over a 120 x 120 mm working area. We have surveyed different fabrication techniques: direct writing lithography,mask manufacturing for contact lithography and polymer laser ablation for complex 3D devices, achieving width channels down to 13μ m on 50μ m SU-8 thickness using direct writing lithography, and width channels of 40 μm for polyimide on SiO2 plate. Finally, we have tested the use of some devices for capillary chips measuring the flow speed for liquids with different viscosities. As a result, we have characterized the presence of liquid in the channel by interferometric microscopy

Revisión y actualización de la eficacia del screening o cribado en la escoliosis idiopática del adolescente.

La escoliosis idiopática del adolescente es el tipo más frecuente de escoliosis. Actualmente, la realización rutinaria de un "screening" o cribado para la escoliosis resulta ser un tema controvertido puesto que existen dudas sobre su eficacia real en disminuir la tasa de cirugía en estos pacientes y supone una importante tasa de falsos positivos. Se realiza, por ello, una revisión y actualización sobre el tema del "screening" en la escoliosis idiopática del adolescente.Adolescent idiopathic scoliosis is the most common type of scoliosis. Nowadays, routine screening in scoliosis turns out to be controversial as to there are doubts about its actual effectiveness in reducing the rate of surgery in these patients and its significant rate of false positives. Therefore, a review and update on the current status of the issue of screening in adolescent idiopathic scoliosis is made