Sara Pimenta

Optical Microsystem for Analysis of Diffuse Reflectance and Fluorescence Signals Applied to Early Gastrointestinal Cancer Detection

The detection of cancer at its earliest stage is crucial in order to increase the probability of a successful treatment. Optical techniques, specifically diffuse reflectance and fluorescence, may considerably improve the ability to detect pre-cancerous lesions. These techniques have high sensitivity to some biomarkers present on the tissues, providing morphological and biochemical information of normal and diseased tissue. The development of a chip sized spectroscopy microsystem, based on these techniques, will greatly improve the early diagnosis of gastrointestinal cancers. The main innovation is the detection of the spectroscopic signals using only few, but representative, spectral bands allowing for miniaturization. This paper presents the mathematical models, its validation and analysis for retrieving data of the measured spectroscopic signals. These models were applied to a set of phantoms clearly representative of gastrointestinal tissues, leading to a more accurate diagnostic by a pathologist. Moreover, it was demonstrated that the models can use the reconstructed spectroscopic signals based only on its extraction on those specific spectral bands. As a result, the viability of the spectroscopy microsystem implementation was proved.

A Complete Blood Typing Device for Automatic Agglutination Detection Based on Absorption Spectrophotometry

Blood type determination is an important clinical test that should be performed before any blood transfusion. However, in emergency situations, due to the patients condition, there may not be enough time to determine the patients blood type. In these cases, the O negative blood type is administered, because it causes less incompatibility risk to the patient. This paper presents a low-cost and portable device for ABO, Rh phenotype, reverse, and Cross-matching human blood typing, based on a spectrophotometric approach of the agglutination detection, with a fast response time (results in <;5 min). These features allow the device operation in mobile emergency units, outside conventional clinical laboratories, and close to the patient. It avoids the risk of incompatibility between the donors and receptors blood, improving the quality in healthcare services.

Design and fabrication of SiO2/TiO2 and MgO/TiO2 based high selective optical filters for diffuse reflectance and fluorescence signals extraction

This paper presents the design, optimization and fabrication of 16 MgO/TiO2 and SiO2/TiO2 based high selective narrow bandpass optical filters. Their performance to extract diffuse reflectance and fluorescence signals from gastrointestinal tissue phantoms was successfully evaluated. The obtained results prove their feasibility to correctly extract those spectroscopic signals, through a Spearmans rank correlation test (Spearmans correlation coefficient higher than 0.981) performed between the original spectra and the ones obtained using those 16 fabricated optical filters. These results are an important step for the implementation of a miniaturized, low-cost and minimal invasive microsystem that could help in the detection of gastrointestinal dysplasia.

Development of an automatic electronic system to human blood typing

Blood typing has a vital contribution to the success of life-saving procedures, such as blood transfusions, and it can be critical, especially in emergency situations. For that, in this paper the main principles to the development of a miniaturized, low cost, portable and automatic system to human blood typing, in emergency situations, are presented. In a previous study, the authors validated a general experimental protocol to be applied in the automatic system. Now, the implementation of a specific light source system by using standard Light Emission Diodes (LEDs) was studied. Moreover, the specification of all electronic components to be used in the prototype device was performed.

Study of the fluorescence signal for gastrointestinal dysplasia detection

The detection of cancer at the dysplasia stage is one of the most important goals in biomedical research. Optical techniques, specifically diffuse reflectance and intrinsic fluorescence, may improve the ability to detect gastrointestinal (GI) cancers, since they have exquisite sensitivity to some intrinsic biomarkers present on the tissues. This work follows the research that has been done towards the implementation of a spectroscopy microsystem for the early detection of GI cancers. For that purpose, the behavior of the fluorescence signal, at different temperatures and considering the most important biomarkers in GI malignancy detection, was studied and presented.

Spectroscopy and pH biosensors for the detection of gastrointestinal dysplasia

The key to successful treatment of gastrointestinal (GI) cancer is the ability to detect the cancer at its earliest stages, called “dysplasia”. Optical techniques may considerably improve the ability to detect dysplasia as they have the potential to provide morphological and biochemical information of normal and diseased tissue. The proposed research project relies in the development of a chip-sized spectroscopy microsystem for the detection of morphological and biochemical tissue changes. Moreover, pH biosensors will be developed, and incorporated on the same chip, which will add essential diagnostic information as a complement to spectroscopy.