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

Abstract

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.

Wavelength Optimization for Quantitative Spectral Imaging of Breast Tumor Margins

“…By solving a linear equation based on a modified Beer-Lambert Law, Umeyama and Yamada accounted for cross-talk of measured NIR chromophores in wavelength combinations for studying the brain [12]. Ferreira et al presented a device fabrication driven strategy for the spectroscopic imaging of esophageal tissue, featuring 16 discrete wavelengths in the 350–750 nm range [13]. The selection of wavelengths was constrained by the filter fabrication process, i.e.…”

Design and fabrication of SiO_2/TiO_2 and MgO/TiO_2 based high selective optical filters for diffuse reflectance and fluorescence signals extraction

“…Therefore, in a Fabry-Perot optical filter the thickness of the resonance cavity determines the tuned wavelength, for the same mirrors films. Taking advantage of that, 16 optical filters centered at specific spectral bands, ranging from 350 to 750 nm, previously considered relevant to extract the spectroscopic signals to GI dysplasia detection [9], were computationally designed using the software TFCalc 3.5 and the Sopra database for the materials refractive indices. During this step, the transmittance peak and the FWHM (Full Width at Half Maximum) of the filters were analyzed.…”

“…For the reported application, the intensity of the transmitted peak should be high, with at least twice the intensity of any noise peak that might appear in the considered spectral range. Concerning the FWHM, a value around 10 nm is enough, once the 16 required spectral bands are centered at 350, 370, 380, 400, 420, 450, 480, 510, 540, 560, 580, 600, 620, 650, 700 and 750 nm [9].…”

“…Previous work [9] carried out by some members of the research team showed the viability of replacing a conventional spectrograph by 16 narrow bandpass optical filters to extract the diffuse reflectance signal from GI tissues and to acquire tissue optical properties, featuring dysplasia diagnostics. However, in that study, only 6 SiO 2 /TiO 2 based optical filters (in the visible spectral range) were fabricated and their spectral performance was evaluated using only a single tissue phantom and only for diffuse reflectance signal extraction, which may not be enough for a complete GI tissue characterization.…”

“…Thus, the fluorescence signal extraction also plays an important role on the GI tissue characterization. Moreover, in the previous work [9], the authors emphasized the importance of an optimization of the optical filters fabrication process, in order to improve their performance.…”