Cell detection and counting through cell lysate impedance spectroscopy in microfluidic devices

Xuanhong Cheng, BioMEMS Resource Center and Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children
Yi-shao Liu, Purdue University
Daniel Irimia, BioMEMS Resource Center and Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children
Utkan Demirci, BioMEMS Resource Center and Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children
Liju Yang, Purdue University
Lee Zamir, Partners AIDS Research Center, Massachusetts General Hospital
William R. Rodríguez, Partners AIDS Research Center, Massachusetts General Hospital
Mehmet Toner, BioMEMS Resource Center and Center for Engineering in Medicine, Massachusetts General Hospital, Harvard Medical School, and Shriners Hospital for Children
Rashid Bashir, Birck Nanotechnology Center and Bindley Bioscience Center, Purdue University

Date of this Version

June 2007

Citation

DOI: 10.1039/b705082h

This document has been peer-reviewed.

 

Abstract

Cell-based microfluidic devices have attracted interest for a wide range of applications. While optical cell counting and flow cytometry-type devices have been reported extensively, sensitive and efficient non-optical methods to detect and quantify cells attached over large surface areas within microdevices are generally lacking. We describe an electrical method for counting cells based on the measurement of changes in conductivity of the surrounding medium due to ions released from surface-immobilized cells within a microfluidic channel. Immobilized cells are lysed using a low conductivity, hypotonic media and the resulting change in impedance is measured using surface patterned electrodes to detect and quantify the number of cells. We found that the bulk solution conductance increases linearly with the number of isolated cells contributing to solution ion concentration. The method of cell lysate impedance spectroscopy is sensitive enough to detect 20 cells mu L-1, and offers a simple and efficient method for detecting and enumerating cells within microfluidic devices for many applications including measurement of CD4 cell counts in HIV patients in resource-limited settings. To our knowledge, this is the most sensitive approach using non-optical setups to enumerate immobilized cells. The microfluidic device, capable of isolating specific cell types from a complex bio-fluidic and quantifying cell number, can serve as a single use cartridge for a hand-held instrument to provide simple, fast and affordable cell counting in point-of-care settings.

 

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