Date on Master's Thesis/Doctoral Dissertation

8-2021

Document Type

Master's Thesis

Degree Name

M. Eng.

Department

Mechanical Engineering

Committee Chair

Williams, Stuart

Committee Co-Chair (if applicable)

Brehob, Ellen

Committee Member

Brehob, Ellen

Committee Member

Harnett, Cindy

Author's Keywords

mechanical engineering; phytoplankton suspensions; impedance spectroscopy

Abstract

Phytoplankton are closely monitored because of their important environmental role, and the impacts they have on their local ecosystems. Some phytoplankton respond to stress by producing lipids, which can be harvested for biofuels and other chemicals. Microfluidic devices have been important in improving the portability and throughput of phytoplankton characterization methods, increasing their potential for in situ use. This study utilized a small sample of phytoplankton suspended in a stagnant medium and measured the impedance response using a lab-on-chip and impedance analyzer. The individual cell characteristics were derived from the impedance response of the group. The goal was to characterize and differentiate between algae species, as well as healthy and nitrogen deprived cells. The average cytoplasm conductivity was 14.4 mS/m for Chlamydomonas reinhardtii and Selenastrum capricornutum, and not differentiable. The species’ average membrane capacitances were differentiable, with S. capricornutum’s being 40.6 mF/m2, and nitrogen-sufficient C. reinhardtii’s being 15.5 mF/m2. Nitrogen-deficient C. reinhardtii’s average cytoplasm conductivity and membrane capacitance were 14.1 mS/m and 13.2 mF/m2.

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