Stretchable electrical cell-substrate impedance sensor platform for monitoring cell monolayers under strain

Abstract

Stretchable microelectrodes paired with an ultra-elastic substrate can be used for electrical sensing of mechanically stretched cells and cell monolayers. Here, we present the development of a cell-stretching platform with thin-film interdigitated microelectrodes. Up to 35 % cyclic stretch are feasible with a novel interlaced meander design connected to the microelectrodes and using Poly(dimethylsiloxane) (PDMS) with a Young’s modulus of 50 kPa as an ultra-elastic substrate. Reliable electrical contacting of the microelectrodes under stretch was achieved by perforation of the contact pads. The novel platform enables label-free, real-time electrical cell-substrate impedance (ECIS) monitoring of cell monolayers. Proof-of-concept experiments indicated that electrical impedance of Madin-Darby canine kidney (MDCK) cell monolayers increased sharply by uniaxial mechanical strain above 20 %. For comparison, human alveolar basal epithelial adenocarcinoma (A549) cell monolayers, which are known to lack mature cell junctions, showed a continuous decrease of electrical impedance over the whole applied strain range of 35 %. The data reveal that impedance changes upon stretching depend on epithelial cell types and existence of tight cellular junctions. The system provides the basis for reliable continuous long-term monitoring of electrical properties of cell monolayers under strain by electrical impedance spectroscopy, e.g., to monitor epithelial permeability changes in real time and under label-free conditions to screen the influence of pharmacological substances.