Development of an optimized algorithm for the characterization of microflow using speckle patterns present in optical coherence tomography signal

Author(s)

Lucas Ramos de Pretto

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Pesquisas Energéticas e Nucleares (IPEN/BT)
• Defense date: 2015-03-20

Examining board members

Anderson Zanardi de Freitas; Anderson Stevens Leonidas Gomes; Marcus Paulo Raele

• Advisor: Anderson Zanardi de Freitas

Abstract

This work discusses the Optical Coherence Tomography system (OCT) and its application to the microfluidics area. To this end, physical characterization of microfluidic circuits were performed using 3D (three-dimensional) models constructed from OCT images of such circuits. The technique was thus evaluated as a potential tool to aid in the inspection of microchannels. Going further, this workpaper studies and develops analytical techniques for microfluidic flow, in particular techniques based on speckle pattern. In the first instance, existing methods were studied and improved, such as Speckle Variance - OCT, where a gain of 31% was obtained in processing time. Other methods, such as LASCA (Laser Speckle Contrast Analysis), based on speckle autocorrelation, are adapted to OCT images. Derived from LASCA, the developed analysis technique based on intensity autocorrelation motivated the development of a custom OCT system as well as an optimized acquisition software, with a sampling rate of 8 kHz. The proposed method was, then, able to distinguish different flow rates, and limits of detection were tested, proving its feasibility for implementation on Brownian motion analysis and flow rates below 10 μl/min. (AU)

• FAPESP's process: 13/05492-9 - Characterization of microfluidic circuits using speckle patterns in optical coherence tomography images
• Grantee: Lucas Ramos de Pretto
• Support Opportunities: Scholarships in Brazil - Master