12 November 2005 Studies of deionization and impedance spectroscopy for blood analyzer
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Blood analysis provides vital information for health conditions. For instance, typical infection response is correlated to an elevated White Blood Cell (WBC) count, while low Red Blood Cell (RBC) count, hemoglobin and hematocrit are caused by anemia or internal bleeding. We are developing two essential modules, deionization (DI) chip and microfluidic cytometer with impedance spectroscopy flow, for enabling the realization of a single platform miniaturized blood analyzer. In the proposed analyzer, blood cells are preliminarily sorted by Dielectrophoretic (DEP) means into sub-groups, differentiated and counted by impedance spectroscopy in a flow cytometer. DEP techniques have been demonstrated to stretch DNA, align Carbon Nanotubes (CNT) and trap cells successfully. However, DEP manipulation does not function in biological media with high conductivity. The DI module is designed to account for this challenge. H Filter will serve as an ion extraction platform in a microchamber. Sample and buffer do not mix well in micro scale allowing the ions being extracted by diffusion without increasing the volume. This can keep the downstream processing time short. Micro scale hydrodynamic focusing is employed to place single cell passing along the central plane of the flow cytometer module. By applying an AC electrical field, suspended cells are polarized, membrane capacitance Cm, cytoplasm conductivity σc, and cytoplasm permittivity εc will vary as functions of frequency. Tracing back the monitored current, the numbers of individual cell species can be evaluated.
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Charlotte C. Kwong, Charlotte C. Kwong, Nan Li, Nan Li, Chih-Ming Ho, Chih-Ming Ho, } "Studies of deionization and impedance spectroscopy for blood analyzer", Proc. SPIE 6003, Nanostructure Integration Techniques for Manufacturable Devices, Circuits, and Systems: Interfaces, Interconnects, and Nanosystems, 60030N (12 November 2005); doi: 10.1117/12.637567; https://doi.org/10.1117/12.637567

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