An overview of key results, challenges and mitigation measures is discussed below for the different technological building blocks and the system as a whole.
Lateral Mixing
Key results: Novel designs to induce electroosmotic flows in polymer chromatographic columns (Innovation 1) were proposed (µFlow).
Key challenges and mitigation: During testing, channels got blocked by debris. Mitigation included analysis of the manufactured chips (prior to shipment to the partners), which revealed no debris that could block the channels (JOR). JOR designed on-chip debris trapping strategies to prevent debris injection in the microfluidic channels during the testing period. Use of MEMS (cleanroom fabrication) to improve control over electrode deposition, dimensions, uniformity, and EOF, will also be considered, then transition back to polymer chips (µFlow).
Polymer pillar array
Key results: Novel designs (Innovation 1) for microfluidic channels with and without pillars (µFlow) were optimized for UV-NIL manufacturing on polymer or electrode substrates (JOR), considering sheet-to-sheet and roll-to-roll production (JOR). Manufacturing process (mastering, UV-NIL, lamination) established for polymeric microfluidic chips including pillar filled channels, different electrode materials and 2 optical detection units, enabling scalable cost-effective R2R production (JOR). UV-NIL process established and shown for microfluidic imprints with defined shape of the channel cross section, high aspect ratio up to 10 and channel geometries down to 3µm x 7µm (JOR). Implementation of transparent electrodes on top and bottom of the channels developed (JOR). Metallization concept for electrode integration after UV-NIL imprinting of microfluidic structures (JOR). This metallization concept can be implemented straightforward in roll-to-roll manufacturing.
Key challenges and mitigation: Definition of a UV-NIL process chain to deliver residual layer-free microfluidic channels. Plasma process for removing residual layer used as mitigation (JOR, NCSRD).
Lamination & bonding
Key results: Development of a bonding process (Innovation 3) including the formulation of adhesives, which can be applied for narrow microfluidic channels with integrated electrodes (JOR).
Key challenges and mitigation: Clogging of channels by adhesives, contamination of electrodes with adhesives. Mitigation by use of UV-transfer bonding with optimized adhesive formulations and processes (JOR). JOR has presented an alternative mitigation strategy with a new concept combining lamination and in-channel functionalization (Innovation 8). CPI and µFlow are open for collaboration to test different coating strategies.
Nanotexturing/porosification
Key results: The potential of the nanotexturing technology previously developed by NCSRD for porosification of polymer chromatographic columns was demonstrated (Innovation 4). Moreover, B-PHOT and NCSRD cooperated to use this same nanotexturing technique to make SERS substrates with superior performance (Innovation 9).
Functional chromatographic coating
Key results: In VortexLC, partner CPI pioneered the deposition of reversed-phase and cation-exchange chromatographic stationary phases using plasma deposition (Innovation 5).
Sample preparation module
Key results: In VortexLC, NCSRD developed a polymeric microdevice for efficient filtering of red blood cell (RBC) debris, with 97% filter efficiency demonstrated in the project (Innovation 10).
UV/VIS and SERS detection
Key results: Novel designs for miniaturization and on-chip integration of UV/VIS and SERS detection (B-PHOT, µFlow) and UV-NIL strategies to manufacture such devices (JOR).
Key challenges and mitigation: Fluidic inlets and outlets interfere with optical detection path. Redesign chip architecture to spatially decouple fluidic ports from the optical detection path (e.g. vertical routing, shielding layers, or relocated interfaces) (µFlow, B-PHOT). SERS surface fabrication is complex when integrated with separation columns and UV/VIS detection; decoupling may be required. Develop separate SERS module (decoupled from the separation and detection system) (B-PHOT).
System integration
Key results: Achievements in all above building blocks were combined with contributions of all partners to demonstrate first concepts of a novel polymeric chromatographic column (Innovation 6) and an instrument to use these columns for point-of-care quantification of HbA1c and other Hb variants (Innovation 7). Manufacturing route for microfluidic chromatographic chip incorporating all elements and design optimized for UV-NIL established (JOR), including distributors, microfluidic channel with electrodes and pillars, optical SERS detection unit, and RI detection unit (JOR). CPI, in collaboration with µFlow and JOR, developed a roadmap for roll-to-roll mass manufacturing of chromatography columns, including UV-imprinting, plasma nanotexturing , plasma coating, and chip lamination.
