Design and validation of a multi-electrode bioimpedance system for enhancing spatial resolution of cellular impedance studies.

This paper reports the design and evaluation of a multi-electrode design that improves upon the statistical significance and spatial resolution of cellular impedance data measured using commercial electric cell-substrate impedance sensing (ECIS) systems. By evaluating cellular impedance using eight independent sensing electrodes, position-dependent impedance measurements can be recorded across the device and compare commonly used equivalent circuit and mathematical models for extraction of cell parameters. Data from the 8-electrode device was compared to data taken from commercial electric cell-substrate impedance sensing (ECIS) system by deriving a relationship between equivalent circuit and mathematically modelled parameters.

From cellular cultures to cellular spheroids: is impedance spectroscopy a viable tool for monitoring multicellular spheroid (MCS) drug models?

The use of 3-D multicellular spheroid (MCS) models is increasingly being accepted as a viable means to study cell-cell, cell-matrix and cell-drug interactions. Behavioral differences between traditional monolayer (2-D) cell cultures and more recent 3-D MCS confirm that 3-D MCS more closely model the in vivo environment. However, analyzing the effect of pharmaceutical agents on both monolayer cultures and MCS is very time intensive.

Real-time impedance analysis of silica nanowire toxicity on epithelial breast cancer cells.

Silica nanowires have great potential for usage in the development of highly sensitive in vivo biosensors used for biomarker monitoring. However, careful analysis of nanowire toxicity is required prior to placing these sensors within the human body. This paper describes a real-time and quantitative analysis of nanowire cytotoxicity using impedance spectroscopy; improving upon studies that have utilized traditional endpoint assays.

Effect of diffusion on impedance measurements in a hydrodynamic flow focusing sensor.

This paper investigated the effects of diffusion between non-conductive sheath and conductive sample fluids in an impedance-based biosensor. Impedance measurements were made with 2- and 4-electrode configurations. The 4-electrode design offers the advantage of impedance measurements at low frequencies (<1 kHz) without the deleterious effects of double layer impedance which are present in the 2-electrode design.

Design rule for optimization of microelectrodes used in electric cell-substrate impedance sensing (ECIS).

This paper presents an experimentally derived design rule for optimization of microelectrodes used in electric cell-substrate impedance sensing (ECIS) up to 10MHz. The effect of change in electrode design (through electrode sensor area, lead trace widths, and passivation coating thickness) on electrode characteristics was experimentally evaluated using electrochemical impedance spectroscopy (EIS) measurements and analyzed using equivalent circuit models. A parasitic passivation coating impedance was successfully minimized by designing electrodes with either a thicker passivation layer or a smaller lead trace area.