Débora R. S. M. Ferreira

Narrow-band pass filter array for integrated opto-electronic spectroscopy detectors to assess esophageal tissue.

A strategy for spectroscopy tissue diagnosis using a small number of wavelengths is reported. The feasibility to accurately quantify tissue information using only 16 wavelengths is demonstrated with several wavelength reduction simulations of the existing esophageal data set. These results are an important step for the development of a miniaturized, robust and low-cost spectroscopy system. This system is based on a sub-millimeter high-selective filter array that offers prospects for a simplified miniature spectrographic detector for a future diagnostic tool to improve the diagnosis of dysplasia. Several thin-film optical filters are optimized and fabricated and its spectral performance is shown to be sufficient for the selection of specific wavelength bands.

Spectroscopy microsystem for the detection of early cancer

The research team is focused on the development of a chip-sized spectroscopy microsystem for the detection of gastrointestinal (GI) early cancerous lesions. The paper will briefly cover the outstanding properties of diffuse reflectance and fluorescence spectroscopy detection and the concept of cointegration of highly selective thin-films optical interference filters on silicon photodiodes, in order to meet the growing clinical demands for highly sensitive and reliable tools for the detection of early cancer in the GI tract. It will be also described some of the developments on-going by the research team.

Fluorescence and diffuse reflectance spectroscopy for early cancer detection using a new strategy towards the development of a miniaturized system

This paper describes the design of a miniature, cost-effective spectroscopy system for assessing tissue biochemical and morphological information using a few wavelengths. This instrument will integrate thin-film optical filters and silicon photodiodes, avoiding the use of a spectrograph and optical fibers. The components in the set-up design are described. The feasibility of using only 16 wavelengths to accurately extract tissue properties is confirmed on physical tissue models. Also, the suitable spectral performance of several optical filters for the selection of these wavelengths is demonstrated. The reduced size of this device will make possible its implementation in an endoscopic capsule.

Stereoscopic image sensor with low-cost RGB filters tunned for the visible range

This paper presents a low-cost technology for fabricating optical filters arrays tuned for the primary colors. The fabrication process presented in this paper is intended for directly printing the optical filters into a transparent flexible substrate (acetate). The target application of these optical filters is for enabling the acquisition of multicolor stereoscopic images with a sensor made in CMOS technology.

DEVELOPMENT OF AN EX VIVO QUANTITATIVE SPECTROSCOPIC SCANNER

We describe an ex vivo quantitative spectroscopy (QS) scanning platform which enables integration of different optical modalities for the assessment of ex vivo tissue properties. As a first implementation, the QS scanner combines diffuse reflectance spectroscopy (DRS) and intrinsic fluorescence spectroscopy (IFS) to provide a multidimensional image of tissue structural and biochemical properties. The wide area coverage is achieved by mechanically scanning of the optical probe. The spectroscopic data is taken one grid at a time with variable grid-to-grid (GTG) distance and field of view (FOV). The ex vivo tissue surface under examination can have a variable size since both GTG distance and FOV can be controlled. We demonstrate the clinical utility of this system using an ex vivo tissue model with ultimate goal of imaging excised tissue

A strategy for spectroscopic diagnosis of dysplasia using a miniaturized system for endoscopic capsules

This paper describes a strategy for the detection of gastrointestinal (GI) dysplasia using a miniaturized system to be integrated within an endoscopic capsule. This system will be able to perform spectroscopy measurements in specific spectral bands, which have the potential to provide biological information of normal and diseased tissue. The designed instrument is based on highly selective thin-film optical filters and silicon photodiodes for the selection and detection of different spectral bands significant for diagnosis. A thin-film optical interference filter and a silicon photodiode were designed and fabricated for diffuse reflectance measurements in the green spectral band. A qualitative analysis of GI spectroscopic data using this specific spectral band is performed. Using a single optical filter, a good sensitivity and specificity were obtained for the diagnosis of GI dysplasia.