Cell impedance measurements through a double approach: M4N and litho-fabricated microelectrodes and microfluidics.

Within the frame of biomedical research and specifically taking advantage of the multiple experimentation possibilities opened by the synergy between electronics and biology, emerges the presented work. The following is an experimental thesis developed in collaboration between Politecnico di Torino and the Company Eltek S.p.A (Hone, Valle D’Aosta, Italia headquarters). The present work is motivated by the advantages that going to the micro and the nano-scale can offer to cell biology for applications in health and environmental sciences. To do so, many challenges in areas such as microelectronics and microfluidics emerge. In this thesis, the subject is approached focusing on impedance measurement analysis. Using impedance changes as an indicator provides the advantages of a label-free technique with a high scalability potential. Two main experimental projects are proposed. The first one is the M4N characterization in aqueous environment motivated by the aim of inquiring the potential of this multisensory platform for bio-sensing applications. This part was specifically directed towards a proof of concept on cell impedance measurement. Experiments werte conducted with yeast cells and a preliminary study of the M4N as a gas sensing platform is also presented. The second project, consists on microelectrodes fabrication through photolithographic techniques and their successive integration with microchannels for cell impedance measurement purposes. Different configurations of electrodes and microchannels are presented. Tests were conducted with yeast cells and a direct relation between concentration and impedance was observed. Impedance measurements in microchannels with interdigitated microelectrodes, in contrast to analog measurements in culture wells, showed to solve the problem of aggregates formation on the electrode surface, showed enhanced sensibility, and reduction in measuring time and sample volumes. Impedance was measured with two different instruments: a commercial impedance-meter and an acquisition system designed and developed at the Company Eltek S.p.A.