Membrane type comparison and modification to modulate sample flow in paper diagnostics

Paper-based diagnostics are rapid, robust, affordable and user-friendly, thus have potential for point-of-care. Modulation of sample flow in these technologies have the advantage of increased exposure between immunoreagents, which ensures higher sensitivity and specificity. In this study, common membrane types were compared and modified to modulate sample flow. Five different membranes were compared: glassfiber, polyester, nitrocellulose, polyvinylidene-difluoride and cellulose. Several parameters were tested for their effect on the sample flow: membranes absorption capacity, immobilization of buffer solution, different membrane types as separation layer and sample volume. The effect of separation membrane on the sample flow was tested using a ‘Stack-Pad’ sensor layout. Higher antibody levels could reach the three absorption pads, with the use of polyester separation membrane (340, 440 and 408 RLU), as compared to the glassfiber separation membrane (208, 198 and 107 RLU), thus potentially increasing the sensor sensitivity. Lastly, the effect of the membrane type and its modifications on the detection sensitivity was also compared. The finalized modified setup (862 RLU) demonstrated a higher detection sensitivity vs. the initial setup (290 RLU). To conclude, the selection of membrane types and their modifications can modulate sample flow and increase the sensitivity of detection in paper diagnostics.