Deposition of functional polymer thin films with tunable morphology using an ambient air-fed microwave plasma jet for the fabrication of biosensor interfaces

Abstract Surface modifications that enable the immobilization of bioreceptors on the signal transducer surfaces of biosensors are typically achieved via wet chemical techniques. Such techniques usually require multistep procedures and hazardous chemicals, and the stability of the resulting interfaces is often a challenge. As an alternative approach, plasma polymerization using a compact and cost-effective microwave plasma source operated at atmospheric pressure and fed with ambient air as the process gas is evaluated in this study. Plasma exposure of the non-hazardous monomeric precursor pentaerythritol tetraacrylate results in the formation of highly stable plasma-polymerized thin films (pp-films) with carboxyl (COOH) groups for the covalent immobilization of bioreceptors. The morphology of the pp-films was tuned by varying the monomer injection time. In this manner, the surface area for bioreceptor coupling and the electronic transfer properties of pp-films deposited on screen-printed electrodes were adjusted and optimized. Finally, glucose oxidase was immobilized on the pp-films and subsequently used for the quantification of glucose via an amperometric readout to demonstrate the suitability of the concept for biosensing. In this context, glucose was quantified in a concentration range of 1–10 mM, with a linear working range of 1–4 mM.