Speakers
Description
Point-of-care testing (POCT) puts forward compulsory requirements on analytical platforms to realize the perfect combination of high detection sensitivity, fast response dynamics, low expenditure and single-use function. Electrochemical biological sensing devices based on printed electrodes are a revolutionary technological framework that overcome the operational limitations of traditional rigid solid-state electrodes with the scalability of additive manufacturing. This review provides a systematic appraisal of printed electrodes, based on three main pillars: conductive material, substrate support and manufacturing techniques. Electrochemical window, background capacitance and synergistic charge-transfer dynamics are reviewed for conductive matrices such as carbon allotropes, noble metals and polymer-nanoparticle composites. Rigid ceramics for high-thermal stability, flexible polymers (PET, PI, PDMS) for wearable detection, and cellulose paper for environmentally friendly, pump-free capillary microfluidic applications are included in the substrate selection. We critically compared the manufacturing approaches including mass-scalable screen printing, maskless inkjet printing and laser-induced graphene in terms of their spatial resolution, fluidic requirements and production throughput. Most importantly, the key role of surface functionalization to transform chemically inert printed surfaces into ultra-sensitive biological interfaces is emphasized. Oxygen plasma modification can introduce oxygenated functional groups (hydroxyl, carboxyl) that reduce the charge-transfer resistance by more than 1000-fold and enhance covalent antibody immobilization for disease biological marker detection. We also fabricate state-of-the-art biological interfaces including oriented aptamer self-assembled monolayers, 3D DNA tetrahedral scaffolds with sub-femtomolar detection limits (74 aM) and antifouling coatings. Finally, a rational selection scheme is proposed to optimize the electrode configurations based on the analyte chemistry, operating conditions and production scales, providing practical insights for sophisticated clinical diagnostic applications.
