Optically transparent diamond-PDMS microfluidic system for electronic monitoring of cells

By combination of diamond thin films with a polydimethylsiloxane (PDMS) microfluidic channel, we realize a system for electronic and optical monitoring of cells under in vivo-like conditions of culturing medium exchange with no direct contact to ambient air. We make use of surface conductivity and high optical transparency of hydrogen-terminated nanocrystalline diamond films (thickness 400 nm) to create a microscopic impedance electrode or transistor channel. We show that the diamond-PDMS system exhibits stable adhesion at least up to 5 mu L min(-1) flow and electrical sensitivity to adsorption of bovine serum albumin. Next, HeLa cells were cultured in the diamond-PDMS channel while electric cell-substrate impedance sensing and optical microscopy were used for long-term (168 h) cell culture monitoring. We observe correlation of the cell culture morphology and impedance characteristics as a function of time. These results confirm the applicability of the diamond-PDMS microfluidic system. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim