Abstract

Advanced Integrated Optical Oxygen and pH Sensors for Organ on Chip Applications

Torsten Mayr, Associate Professor, Leader-Applied Sensors, Graz University of Technology Austria

Optical chemical sensors comprise of luminescent indicator dye based in a host polymer. They are easy to integrate, non-invasive, do not need any reference element and can be read-out contactless from outside. However, to fully exploit the potential in microfluidic or organ-on- chip devices, the sensors have to fulfil several demands including high brightness, capability to be applied as thin film, excellent photo-stability, cheap and accurate read-out systems, ease in use (simple calibration and drift free), simple mass production compatible preparation steps, compatibility with the chip materials, resistance towards ?-sterilisation and no toxicity. We present sensors for oxygen, pH and glucose fulfilling these demands. Our sensors can be excited with red-light and emit light in the near infra-red range (<700 nm). This suppresses background fluorescence or scattering from biological material. Sensor layers or spots are deposited with inkjet-based microdispensing with good adherence on glass or polymeric materials. A modified miniaturized phase-fluorimeter enables the read-out of sensor sizes below 100 micrometers. In addition, luminescent nanobeads are demonstrated as an attractive alternative to integrated sensor layers since they can be easily injected to the flow, do not interfere with the sample and have fast response times. The sensor enable dynamic cell culturing and monitoring of cell metabolism in a microfluidic environment. We will give examples of oxygen sensors in a liver-on-chip model and pH sensors in cell cultures.