One step multi-material 3D printing for the fabrication of a photometric detector flow cell.

Optical detection is the most common detection mode for many analytical assays. Photometric detection systems and their integration with analytical systems usually require several assembly parts and manual alignment of the capillary/tubing which affects sensitivity and repeatability. 3D printing is an innovative technology for the fabrication of integrated complex detection systems. One step multi-material 3D printing has been explored to fabricate a photometric detector flow cell from optically transparent and opaque materials using a dual-head FDM 3D printer. Integration of the microchannel, the detection window and the slit in a single device eliminates the need for manual alignment of fluidic and optical components, and hence improves sensitivity and repeatability. 3D printing allowed for rapid design optimisation by varying the slit dimension and optical pathlength. The optimised design was evaluated by determining stray light, effective path length and the signal to noise ratio using orange G. The optimised flow cell with extended path length of 10 mm and 500 µm slit yielded 0.02% stray light, 89% effective path length and detection limit of 2 nM. The sensitivity was also improved by 80% in the process of optimisation, using a blue 470 nm LED as a light source.