Capillary Microfluidic Biosensor with PEDOT:PSS Electrodes

The electrode surface is pre-modified with nanomaterials and functional groups during the screen-printing process itself, rather than requiring separate post-preparation steps. The nanomaterial-containing ink is applied and cured to form the electrode structure with built-in functional groups that enable direct biomolecule immobilization, eliminating subsequent functionalization steps.

Multiple functions are combined into a single screen-printing process: electrode fabrication, nanomaterial deposition, surface functionalization, and biomolecule immobilization. The conductive ink contains both the conductive material and functional groups (carboxyl, amine, or hydroxyl groups) that enable direct binding of capture molecules, merging what were previously separate sequential steps into one integrated process.

Functional groups are introduced during the electrode fabrication process itself through the use of functionalized conductive ink, rather than adding them later through separate chemical treatment steps. This preliminary incorporation of functional groups enables immediate use for biomolecule immobilization without time-consuming post-processing.

The complex multi-step functionalization process is extracted and replaced with a single screen-printing step using pre-functionalized conductive ink. The functional groups are already present in the ink formulation, so the screen-printing process directly creates the functional electrode surface without requiring subsequent extraction or isolation steps.

The conductive ink is formulated as a nanocomposite material containing PEDOT:PSS polymer and graphene nanoparticles, combining the electrical conductivity of the polymer with the high surface area and catalytic properties of graphene. This composite material provides enhanced detection performance while maintaining processability through standard screen-printing techniques.

The physical and chemical parameters of the conductive ink are optimized to enable proper screen-printing and curing. The ink viscosity, particle size distribution, and component ratios are adjusted to ensure uniform deposition and effective curing, transforming the complex nanocomposite into a manufacturable material that can be produced using conventional printing processes.

The microfluidic channels are integrated directly with the electrode structure, merging fluid delivery and electrochemical detection into a single integrated platform. The channels are positioned to deliver sample directly to the electrode surface, eliminating the need for separate sample preparation equipment and reducing system complexity.

The integrated device performs multiple functions: sample delivery through microfluidic channels, biomolecule capture on the electrode surface, and electrochemical detection. This multi-functionality consolidates what would traditionally require separate instruments, reducing overall system complexity while maintaining rapid detection capability.