Ultra stable, inkjet-printed pseudo reference electrodes for lab-on-chip integrated electrochemical biosensors

Lab-on-Chip technology comprises one of the most promising technologies
enabling the widespread adoption of Point-of-Care testing in routine clinical
practice. However, until now advances in Lab-on-Chip have not been translated
to the anticipated degree to commercialized tools, with integrated device mass
manufacturing cost still not at a competitive level for several key clinical
applications. Lab-on-PCB is currently considered as a candidate technology
addressing this issue, owing to its intuitive compatibility with electronics,
seamless integration of electrochemical biosensors and the extensive experience
regarding industrial manufacturing processes. Inkjet-printing in particular is a
compatible fabrication method, widening the range of electronic materials
available and thus enabling seamlessly integrated ultrasensitive electronic
detection. To this end, in this work stable pseudo-reference electrodes are fabricated for the first time by means of commercial inkjet-printing on a PCB integrated electrochemical biosensing platform. SEM and XPS analysis are
employed to characterize the electrodes’ structure and composition and identify
any special characteristics, compared to published work on alternative substrates.
Additionally, this paper analyzes integrated reference electrodes from a new
perspective, focusing mainly on their characteristics in real-life operation:
chemical sintering as opposed to high budget thermal one, stability under
continuous flow, pH dependency and bias stress effects on electrode instability, a
parameter often overlooked in electrochemical biosensors.