Design and fabrication of microfluidic actuators towards microanalysis systems for bioaffinity assays

This work presents the design, fabrication and characterization of a polymer based stretchable electrode for cell monitoring. The final goal is the development of innovative bio-hybrid skin-like tactile sensors with mammalian cells as core biological elements; to achieve such aim the enabling technological approach is pursued in this investigation. Electrodes are needed to detect cells response, thus the first step of the bio-hybrid system fabrication is the development of a platform able to record such response and transmit it to the external world. The stretchable electrode is composed by a conductive layer (few Å of Ti plus 90 nm of Au) on a polymeric substrate (1 mm thick PDMS membrane). Cellular adhesion was verified and cellular response to an induced electrode strain of 1% was detected through fluorescence microscopy. Fluorescence intensities were 104.82 ± 9.64 a.u. and 129.66 ± 13.06 a.u. prior and during electrode strain, respectively. Electromechanical characterization of the stretchable electrode revealed excellent stability and reliability within the 1% strain, which is the operative range identified for the future tactile sensor application. Results showed that the electrode was conductive up to 14% of strain. Furthermore, frequency impedance measurements demonstrated the electrode capability of detecting presence of cells.