Traffic light type paper-based analytical device for intuitive and semi-quantitative naked-eye signal readout

Sera Ohta, Ryuya Hiraoka, Yuki Hiruta, Daniel Citterio

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Microfluidic paper-based analytical devices (μPADs) have attracted great attention as potential candidates for point-of-care testing (POCT). Nevertheless, only a limited number of μPADs expected to satisfy the standard of Clinical Laboratory Improvement Amendments (CLIA) waived tests as issued by the US Food and Drug Administration (FDA) have been reported. This work introduces a “traffic light type μPAD”, enabling highly intuitive semi-quantitative equipment-free naked-eye readout with no need for calibration, subjective interpretation or calculation. Assay results are displayed as traffic light colours reporting 5 analyte concentration levels (green/green & yellow/yellow/yellow & red/red). The device has been designed to never display all three colours simultaneously, eliminating any risk for misinterpretation. The mechanism relies on the modulation of sample flow through a network of paperfluidic channels modified with a hydrophobic to hydrophilic phase-switching substance responsive to H2O2. User operation is limited to sample application, followed by observing a clear and time-independent traffic light signal after approximately 10-30 min. Multiple factors influencing the H2O2 concentration-dependent appearance of a specific traffic light signal were studied. Making use of the possibilities for customising the concentration threshold levels for traffic light colour appearance, quantification of glucose at 5 levels in a clinically relevant concentration range was demonstrated in artificial urine as a model proof-of-concept. This platform is expected to offer the possibility for the future detection of other important metabolites.

Original languageEnglish
Pages (from-to)717-726
Number of pages10
JournalLab on a Chip
Issue number4
Publication statusPublished - 2022 Feb 21

ASJC Scopus subject areas

  • Bioengineering
  • Biochemistry
  • General Chemistry
  • Biomedical Engineering


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