Integrating impedance-based growth-rate monitoring into a microfluidic cell culture platform for live-cell microscopy

Abstract

Growth rate is a widely studied parameter for various cell-based biological studies. Growth rates of cell populations can be monitored in chemostats and micro-chemostats, where nutrients are continuously replenished. Here, we present an integrated microfluidic platform that enables long-term culturing of non-adherent cells as well as parallel and mutually independent continuous monitoring of (i) growth rates of cells by means of impedance measurements and of (ii) specific other cellular events by means of high-resolution optical or fluorescence microscopy. Yeast colonies were grown in a monolayer under culturing pads, which enabled high-resolution microscopy, as all cells were in the same focal plane. Upon cell growth and division, cells leaving the culturing area passed over a pair of electrodes and were counted through impedance measurements. The impedance data could then be used to directly determine the growth rates of the cells in the culturing area. The integration of multiple culturing chambers with sensing electrodes enabled multiplexed long-term monitoring of growth rates of different yeast strains in parallel. As a demonstration, we modulated the growth rates of engineered yeast strains using calcium. The results indicated that impedance measurements provide a label-free readout method to continuously monitor the changes in the growth rates of the cells without compromising high-resolution optical imaging of single cells.

Interfacing gene circuits with microelectronics through engineered population dynamics

“…The dynamics of gene circuits have primarily been investigated using well-defined submillimeter-scale bacterial colonies (33)(34)(35). Interfacing synthetic biology with electrodes requires robust population behavior at larger scales (36), where dynamical behaviors are less characterized. To study the dynamic behavior in a macroscale continuous culturing system, we fabricated a customized milliliter scale chemostat with disposable gold electrodes in contact with the culture ( Fig.…”

“…One substantial challenge in synthetic biology is minimally tracking gene expression without the need for fluorescent proteins and associated complex imaging equipment. Given recent efforts in the development of electrochemical platforms (8,36) and the minimal nature of impedance measurement for circuit dynamics by directly connecting bacteria with electrodes, we sought to develop a miniature device to demonstrate the utility of our approach. To accomplish this, we fabricated a fluidic chip with multiple milliscale growth chambers, where each chamber contained electrodes (Fig.…”

Impedance-Based Monitoring of Mesenchymal Stromal Cell Three-Dimensional Proliferation Using Aerosol Jet Printed Sensors: A Tissue Engineering Application

“…Among the available electrical-based cell monitoring techniques, impedance-based solutions represent one of the most adopted approaches, easily integrable with labware and microfluidic devices [15]. Furthermore, this methodology can be applied to a large variety of cells-even non excitable ones-, thus representing a powerful solution with respect to potential-based measurement systems.…”

Design and analysis of microfluidic cell counter using spice simulation

“…The proposed platform was used for the automated antischistosomal drug screening. Chawla [26] also used microfluidic platform for the long-term culturing and high-resolution imaging of yeast cells. Finally, the microfluidic cytometry has also been used for organ on chip applications, e.g., for cell detection with temporal regulation of the cell microenvironment [27], selective detection of the migratory properties of cancer cells [28], and, for measuring Transepithelial electrical resistance (TEER) [29].…”