Cell Culture Impedance Sensing with Thin Film ITO Electrodes

Abstract

The intent of the thesis has been to investigate the suitability of micrometer-scaled interdigitated indium tin oxide (ITO) electrodes for impedance sensing of a monolayer human retinal pigment epithelium (RPE) culture, and to assess atomic layer deposition (ALD) coating as a tool to functionalise the electrode and substrate surfaces. Building a impedance sensing device for cell cultures was part of the work. A cell culture impedance sensing device utilising micrometer-scaled interdigitated ITO electrodes has been designed, prototyped and produced to measure electric properties of a monolayer human RPE cell culture of the ARPE-19 cell line. Design was performed in a CAD tool, plastic parts were printed with a 3D printer; the electrodes were created using laser ablation of a glass plate coated with a 350 nm ITO film; the cell well was cut from a SiO2 glass tube. Equivalent circuit analysis and finite element method (FEM) simulation were performed based on existing research documentation. Toxicity tests for adhesives for the well attachment were performed, resulting in the use of aquarium silicone as adhesive. Interdigitated electrodes with 24 µm and 192 µm digits were used to measure the impedance of an ARPE-19 cell culture. Separate experiments with substrates coated by atomic layer deposition (ALD) technique with titanium tetraisopropoxide (TTIP) and glycine, and with CaCO3 were performed. Impedance measurements indicating cell attachment and proliferation on the different types of substrates and for different electrode dimensions were performed with an impedance analyser; phase contrast optical microscope observations of the cells were performed in parallel. Measurements indicated that the ITO electrodes allowed ARPE-19 cell attachment and proliferation, and were sensitive to the resulting impedance changes. The TiO2/glycine-coated electrodes allowed cell attachment and proliferation but were both unsuccessful in regards to measurement purposes.