CFD Modeling of Chamber Filling in a Micro- Biosensor for Protein Detection
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Date
2017-10
Authors
Islamov, Meiirbek
Sypabekova, Marzhan
Kanayeva, Damira
Rojas-Solórzano, Luis
Journal Title
Journal ISSN
Volume Title
Publisher
Biosensors
Abstract
Tuberculosis (TB) remains one of the main causes of human death around the globe. The
mortality rate for patients infected with active TB goes beyond 50% when not diagnosed. Rapid and
accurate diagnostics coupled with further prompt treatment of the disease is the cornerstone for
controlling TB outbreaks. To reduce this burden, the existing gap between detection and treatment
must be addressed, and dedicated diagnostic tools such as biosensors should be developed. A
biosensor is a sensing micro-device that consists of a biological sensing element and a transducer
part to produce signals in proportion to quantitative information about the binding event. The
micro-biosensor cell considered in this investigation is designed to operate based on aptamers as
recognition elements against Mycobacterium tuberculosis secreted protein MPT64, combined in a
microfluidic-chamber with inlet and outlet connections. The microfluidic cell is a miniaturized
platform with valuable advantages such as low cost of analysis with low reagent consumption,
reduced sample volume, and shortened processing time with enhanced analytical capability. The
main purpose of this study is to assess the flooding characteristics of the encapsulated microfluidic
cell of an existing micro-biosensor using Computational Fluid Dynamics (CFD) techniques. The
main challenge in the design of the microfluidic cell lies in the extraction of entrained air bubbles,
which may remain after the filling process is completed, dramatically affecting the performance of
the sensing element. In this work, a CFD model was developed on the platform ANSYS-CFX using
the finite volume method to discretize the domain and solving the Navier–Stokes equations for both
air and water in a Eulerian framework. Second-order space discretization scheme and second-order
Euler Backward time discretization were used in the numerical treatment of the equations. For a
given inlet–outlet diameter and dimensions of an in-house built cell chamber, different inlet liquid
flow rates were explored to determine an appropriate flow condition to guarantee an effective
venting of the air while filling the chamber. The numerical model depicted free surface waves as
promoters of air entrainment that ultimately may explain the significant amount of air content in
the chamber observed in preliminary tests after the filling process is completed. Results
demonstrated that for the present design, against the intuition, the chamber must be filled with
liquid at a modest flow rate to minimize free surface waviness during the flooding stage of the
chamber.
Description
Keywords
tuberculosis, biosensor, microfluidic cell, multiphase flow, Computational Fluid Dynamics, ANSYS-CFX
Citation
Meiirbek Islamov, Marzhan Sypabekova, Damira Kanayeva, Luis Rojas-Solórzano. 2017. CFD Modeling of Chamber Filling in a Micro- Biosensor for Protein Detection. Biosensors