Bio-sample detection on paper-based devices with inkjet printer-sprayed reagents

• Modify inkjet printer to spray reagent onto paper-based assays.
• Detect AST and ALT accurately by the colorimetric method.
• The device is low-cost and with potential of mass production.

The reagent required for bio-sample detection on paper-based analytical devices is generally introduced manually using a pipette. Such an approach is time-consuming; particularly if a large number of devices are required. Automated methods provide a far more convenient solution for large-scale production, but incur a substantial cost. Accordingly, the present study proposes a low-cost method for the paper-based analytical devices in which the biochemical reagents are sprayed onto the device directly using a modified commercial inkjet printer. The feasibility of the proposed method is demonstrated by performing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) tests using simple two-dimensional (2D) paper-based devices. In both cases, the reaction process is analyzed using an image-processing-based colorimetric method. The experimental results show that for AST detection within the 0–105 U/l concentration range, the optimal observation time is around four minutes, while for ALT detection in the 0–125 U/l concentration range, the optimal observation time is approximately one minute. Finally, for both samples, the detection performance of the sprayed-reagent analytical devices is insensitive to the glucose concentration.

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