{"id":{"repo_id":"missouri","oai_identifier":"oai:mospace.umsystem.edu:10355/14311"},"canonical_url":"https://search.dev.ndltd.org/etd/missouri/oai:mospace.umsystem.edu:10355/14311","repository":{"repo_id":"missouri","name":"University of Missouri","base_url":"https://mospace.umsystem.edu/oai/request"},"display":{"title":"MEMS Coulter counter for dynamic impedance measurement of time sensitive cells","abstract":"[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] In this research, a MEMS Coulter counter is designed, modeled, fabricated and characterized, which can detect and monitor the dynamic cell impedance changes in situ as a function of time and cellular volumetric changes after mixing isolated cell populations with different extracellular media within 0.2 second from the start of mixing. The novelty of this design is the use of multi-electrodes with vertical sidewalls to enable the measurements of time sensitive cells with significantly enhanced sensitivity as well as the integration of passive mixing, focusing of cells in line and impedance detection using the vertical electrodes on a single chip that is made mainly using multilayer of SU-8. The device consists of a mixer with a T-shaped and serpentine shape channels, dielectrophoretic focusing region, and electrical impedance detection region. Multiple pairs of electrodes were distributed throughout the microchannel and the impedance of cells was monitored along the whole Coulter channel as cells pass through. The mixing, focusing and sensing functionalities were first simulated using COMSOL finite element tool. The devices were then fabricated using a series of surface micromachining, SU-8 and PDMS processes on glass slides. The fabricated devices were tested by injecting saline water with different standard size latex microbeads as well as various types of cells including fibroblast cells, red blood cells and yeast cells were mixed with cryoprotectant agent and phosphate buffered solution. To quantitatively evaluate mixing efficiency, image processing technique was used to analyze color intensities variation of captured images of 2 dyed fluids mixed in the channel at different flow rates. Both fluidic and electrical testing results validate the performance of the microfabricated Coulter counter.","abstract_html":"[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] In this research, a MEMS Coulter counter is designed, modeled, fabricated and characterized, which can detect and monitor the dynamic cell impedance changes in situ as a function of time and cellular volumetric changes after mixing isolated cell populations with different extracellular media within 0.2 second from the start of mixing. The novelty of this design is the use of multi-electrodes with vertical sidewalls to enable the measurements of time sensitive cells with significantly enhanced sensitivity as well as the integration of passive mixing, focusing of cells in line and impedance detection using the vertical electrodes on a single chip that is made mainly using multilayer of SU-8. The device consists of a mixer with a T-shaped and serpentine shape channels, dielectrophoretic focusing region, and electrical impedance detection region. Multiple pairs of electrodes were distributed throughout the microchannel and the impedance of cells was monitored along the whole Coulter channel as cells pass through. The mixing, focusing and sensing functionalities were first simulated using COMSOL finite element tool. The devices were then fabricated using a series of surface micromachining, SU-8 and PDMS processes on glass slides. The fabricated devices were tested by injecting saline water with different standard size latex microbeads as well as various types of cells including fibroblast cells, red blood cells and yeast cells were mixed with cryoprotectant agent and phosphate buffered solution. To quantitatively evaluate mixing efficiency, image processing technique was used to analyze color intensities variation of captured images of 2 dyed fluids mixed in the channel at different flow rates. Both fluidic and electrical testing results validate the performance of the microfabricated Coulter counter.","abstract_has_math":false,"creators":["Wu, Yifan"],"institution":"University of Missouri--Columbia","degree_name":"Ph. D.","degree_level":"Doctoral","degree_discipline":"Electrical and computer engineering (MU)","degree_department":null,"school":null,"contributors":[],"advisors":["Almasri, Mahmoud"],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011","date_published":"2011","updated_at":"2026-07-24T03:09:27Z","subjects":["microfluidics","microcounter","cell impedance changes","Coulter counter"],"languages":["eng","English"],"rights":["Access to files is limited to the University of Missouri--Columbia with SSO login."],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.32469/10355/14311"],"render_values":[{"text":"https://doi.org/10.32469/10355/14311","href":"https://doi.org/10.32469/10355/14311","code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/10355/14311","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Almasri, Mahmoud"]},{"key":"dc:creator","label":"Author","values":["Wu, Yifan"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2012-05-22T16:38:04Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2013-07-29T11:15:07Z"]},{"key":"dc:date.issued","label":"Date","values":["2011"]},{"key":"dc:publisher","label":"Institution","values":["University of Missouri--Columbia"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical and computer engineering (MU)"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. 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The novelty of this design is the use of multi-electrodes with vertical sidewalls to enable the measurements of time sensitive cells with significantly enhanced sensitivity as well as the integration of passive mixing, focusing of cells in line and impedance detection using the vertical electrodes on a single chip that is made mainly using multilayer of SU-8. The device consists of a mixer with a T-shaped and serpentine shape channels, dielectrophoretic focusing region, and electrical impedance detection region. Multiple pairs of electrodes were distributed throughout the microchannel and the impedance of cells was monitored along the whole Coulter channel as cells pass through. The mixing, focusing and sensing functionalities were first simulated using COMSOL finite element tool. The devices were then fabricated using a series of surface micromachining, SU-8 and PDMS processes on glass slides. The fabricated devices were tested by injecting saline water with different standard size latex microbeads as well as various types of cells including fibroblast cells, red blood cells and yeast cells were mixed with cryoprotectant agent and phosphate buffered solution. To quantitatively evaluate mixing efficiency, image processing technique was used to analyze color intensities variation of captured images of 2 dyed fluids mixed in the channel at different flow rates. Both fluidic and electrical testing results validate the performance of the microfabricated Coulter counter."]},{"key":"dc:title","label":"Title","values":["MEMS Coulter counter for dynamic impedance measurement of time sensitive cells"]}]}],"canonical_facts":{"dc:contributor.advisor":["Almasri, Mahmoud"],"dc:creator":["Wu, Yifan"],"dc:date.accessioned":["2012-05-22T16:38:04Z"],"dc:date.available":["2013-07-29T11:15:07Z"],"dc:date.issued":["2011"],"dc:description":["Title from PDF of title page (University of Missouri--Columbia, viewed on May 22, 2012).","The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.","Dissertation advisor: Dr. Mahmoud Almasri","Vita.","Includes bibliographical references.","\"May 2011\""],"dc:description.abstract":["[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] In this research, a MEMS Coulter counter is designed, modeled, fabricated and characterized, which can detect and monitor the dynamic cell impedance changes in situ as a function of time and cellular volumetric changes after mixing isolated cell populations with different extracellular media within 0.2 second from the start of mixing. The novelty of this design is the use of multi-electrodes with vertical sidewalls to enable the measurements of time sensitive cells with significantly enhanced sensitivity as well as the integration of passive mixing, focusing of cells in line and impedance detection using the vertical electrodes on a single chip that is made mainly using multilayer of SU-8. The device consists of a mixer with a T-shaped and serpentine shape channels, dielectrophoretic focusing region, and electrical impedance detection region. Multiple pairs of electrodes were distributed throughout the microchannel and the impedance of cells was monitored along the whole Coulter channel as cells pass through. The mixing, focusing and sensing functionalities were first simulated using COMSOL finite element tool. The devices were then fabricated using a series of surface micromachining, SU-8 and PDMS processes on glass slides. The fabricated devices were tested by injecting saline water with different standard size latex microbeads as well as various types of cells including fibroblast cells, red blood cells and yeast cells were mixed with cryoprotectant agent and phosphate buffered solution. To quantitatively evaluate mixing efficiency, image processing technique was used to analyze color intensities variation of captured images of 2 dyed fluids mixed in the channel at different flow rates. Both fluidic and electrical testing results validate the performance of the microfabricated Coulter counter."],"dc:identifier.doi":["https://doi.org/10.32469/10355/14311"],"dc:identifier.uri":["https://hdl.handle.net/10355/14311"],"dc:language":["English"],"dc:language.iso":["eng"],"dc:publisher":["University of Missouri--Columbia"],"dc:rights":["Access to files is limited to the University of Missouri--Columbia with SSO login."],"dc:subject":["microfluidics","microcounter","cell impedance changes","Coulter counter"],"dc:title":["MEMS Coulter counter for dynamic impedance measurement of time sensitive cells"],"dc:type":["Thesis"],"thesis:degree_discipline":["Electrical and computer engineering (MU)"],"thesis:degree_level":["Doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["University of Missouri--Columbia"]},"updated_at":"2026-07-24T03:09:27Z"}