Low-temperature integration of printed electrochemical sensors into OSTE+ micrfluidics for oxygen monitoring and sensing

Abstract

Real-time monitoring of biological events is essential for advancing in drug testing, disease modeling, and precision medicine. However, conventional analytical methods often lack the spatiotemporal resolution to capture dynamic cellular responses, particularly in Organ-on-a-Chip (OoC) platforms and microphysiological systems (MPS). While progress has been made in sensor development, integrating sensors into microfluidic devices remains technically challenging. Materials commonly used in microfluidics, such as polydimethylsiloxane (PDMS), are poorly suited for stable sensor integration due to low metal adhesion. Off-stoichiometry thiol-ene-epoxy (OSTE+) polymers present a promising alternative due to the presence of unreacted thiol groups. These groups enable dual functionalities: strong metal affinity for direct for robust sensor integration, and oxygen scavenging essential for microscale oxygen level control. However, their compatibility with conventional sensor fabrication methods, particularly those requiring elevated temperatures, is limited. This work introduces a low-temperature fabrication method based on inkjet printing and photonic curing, suitable for thermally sensitive substrates. Gold and silver nanoparticle inks were directly sintered onto OSTE+ using photonic curing, producing functional electrochemical sensors for spatially resolved and real-time oxygen detection. Unlike conventional thermal sintering, which is incompatible with many microfluidic materials, photonic curing preserves the chemical reactivity and mechanical properties of the polymer without requiring surface treatment or adhesive layers. To demonstrate functionality, sensors were integrated into microfluidic devices for continuous monitoring of dissolved oxygen. Real-time oxygen depletion driven by the materials intrinsic scavenging capability was successfully quantified. These findings support the compatibility of sensor integration into OSTE+ polymers enhancing the real-time monitoring capabilities in OoC and MPS systems. HighlightsO_LIInkjet-printed sensors are integrated into OSTE+ using a low-temperature protocol. C_LIO_LIPhotonic curing enables sintering of gold and silver nanoparticle inks without damaging the polymer substrate. C_LIO_LIOxygen scavenging is monitored in real time using integrated electrochemical sensors. C_LIO_LITunable oxygen gradients are achieved in OSTE+ microfluidics for organ-on-chip models. C_LI