Low-temperature inkjet-printed electrochemical sensors on OSTE+ microfluidics for oxygen monitoring and scavenging

Abstract

Real-time monitoring of biological processes is crucial for advancing organ-on-a-chip (OoC) and microphysiological systems (MPS) toward more predictive models for drug development, disease modeling, and precision medicine. Achieving this capability requires robust sensor integration strategies that are compatible with the polymers and substrates used in OoC and MPS platforms. Off-stoichiometry thiol-ene-epoxy (OSTE+) polymers are promising material substrates for sensor integration because of their unreacted thiol groups, which enable strong metal affinity for robust sensor integration and intrinsic oxygen scavenging for microscale oxygen control. However, sensor integration is limited by the high-temperature requirements of conventional metal ink sintering. This work introduces a versatile, low-temperature fabrication strategy that combines inkjet printing with photonic curing to directly sinter gold and silver nanoparticle inks on OSTE+ substrates. This method prevents thermal damage, maintains the chemical functionality and mechanical integrity of the polymer. Electrochemical sensors were integrated into microfluidic devices that enable real-time monitoring of dissolved oxygen, quantitatively capturing the intrinsic oxygen-scavenging behavior of the material. These findings demonstrate a robust route for sensor integration in OSTE+, enhancing real-time monitoring in OoC and MPS platforms.