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Electrokinetically Driven Mixing in a Microchamber for Lab-on-a-Chip Applications

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dc.contributor.authorSundaram, Narayanen
dc.contributor.committeechairTafti, Danesh K.en
dc.contributor.committeememberDancey, Clinton L.en
dc.contributor.committeememberSaraf, Ravi F.en
dc.contributor.departmentMechanical Engineeringen
dc.date.accessioned2011-08-06T15:58:27Zen
dc.date.adate2003-12-18en
dc.date.available2011-08-06T15:58:27Zen
dc.date.issued2003-11-21en
dc.date.rdate2003-12-18en
dc.date.sdate2003-12-11en
dc.description.abstractElectrokinetically Driven Mixing in a Microchamber for Lab-on-a-Chip Applications Narayan Sundaram Abstract Micro-Total-Analysis-Systems (μTAS) have been the focus of recent world wide research due to their varied applications. Much of the motivation for the development of μTAS stems from applications in biotechnology and biomedicine. A typical μTAS device includes a number of functional units ranging from sample injection or ingestion, pre-concentration, mixing with reagents, chemical reactions, separation, detection, and possibly a chemical response. Mixing of constituents is one of the key functions desired of these systems for conducting analyses in a short span of time. The flow regime in these small devices (typical sizes 100μm) being predominantly laminar (Reynolds number, Re < 1), it becomes difficult to rapidly mix the constituent species. Hence for effective mixing, it is necessary to increase the Reynolds number and/or induce bulk motion such that the material interface between the components to be mixed is continously augmented. The method developed to induce such motion is by the application of an AC fluctuating potential field across a microchamber in which mixing is to be performed. The externally applied electric field applies a force on free ions in the charged Debye layer very close to the surface (1-10 nanometers) and induces a flow velocity which is proportional to the electric field. This applied fluctuating electric field gives rise to hydrodynamic instabilities which are responsible for increasing the material contact surface and hence augmenting the rate of mixing by an order of magnitude or more over pure diffusion. To further enhance mixing, microbaffles are strategically placed inside the microchamber and the mixing time was further decreased by a factor of two. Mixing was also studied in a neutral (no charge on the walls) microchamber. It was found that the mixing achieved in the absence of surface charge was comparable to the mixing achieved in the case with microbaffles. This work establishes that CFD is a useful tool that is capable of providing insight into the flow physics in devices with very small length scales.en
dc.description.degreeMaster of Scienceen
dc.format.mediumETDen
dc.identifier.otheretd-12112003-155744en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-12112003-155744en
dc.identifier.urihttp://hdl.handle.net/10919/9849en
dc.publisherVirginia Techen
dc.relation.haspartThesis-Sundar.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectElectroosmosisen
dc.subjectMicrobafflesen
dc.subjectMicrochamberen
dc.subjectElectrokinesisen
dc.subjectMicro-Total-Analysis systemsen
dc.titleElectrokinetically Driven Mixing in a Microchamber for Lab-on-a-Chip Applicationsen
dc.typeThesisen
thesis.degree.disciplineMechanical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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