Low Cost EIS Methodology to Characterize Microelectrode Arrays used in Biological Applications
Poster Sep 17, 2014
C. A. Santos *, M. A. Flores*, O. Pilloni* , J. Mireles Jr**., A. Falcón ***, T. Fiordelisio ***, L. Oropeza-Ramos*
Electrical Impedance Spectroscopy (EIS) is a valuable and widespread tool to measure properties of an electrode-electrolyte interface present in micro-arrays platforms for recording and stimulating biological tissues. The electric contact between an electrode and a cellular aqueous medium has an impedance whose high values reduce signal to noise ratio and increase signal distortion. This is particularly relevant for microelectrodes due to their reduced dimensions, and having an EIS method available in every laboratory would be highly useful to design and characterize micro electrodes for bio-potential recording and stimulation.
Commercial EIS systems and alternative set-ups that often require an spectrum analyzer are expensive, limiting the electrochemical characterization. In this work, an EIS diagnostic method is presented based on the combination of a straightforward measurement of the time domain input-output voltage ratio, through a conventional oscilloscope, and the indirect analytical determination of the overall impedance in a user defined frequency range.
The method was validated by characterizing an array of silver-chloride micro electrodes soaked in biological medium, used to maintain in vitro cell cultures alive, and results are compared to a commercial EIS system.
Multiplexing cell-based assays is possible using 3D culture models that are larger and more complex than monolayers
Real-time detection methods to measure live or dead cells provide much flexibility for multiplexing
All multiplexed assay combinations should be verified using appropriate controls for each 3D cell culture model.
Basic fibroblast growth factor (bFGF) is widely used in vitro for the maintenance and stimulation of a variety of cells. However, use of native bFGF in cell biology is limited by the fact that bFGF rapidly degrades at physiological temperatures. We have addressed this problem with an engineered form of bFGF, named Heat Stable bFGF (HS bFGF), which is stable at 37 degrees Celsius.READ MORE