Dual-Enzyme Capillary Flow–Driven Microfluidic Sensor for Multiplexed Screening of Occupational and Take-Home Pesticide Exposure

Over 3.7 million tons of pesticides are applied each year in agriculture to maintain crop production. However, mixing, loading, and spraying expose agricultural workers to pesticide residues. Beyond occupational exposure, take-home pathways, where residues on gloves, clothing, and tools are transported into vehicles and homes, pose additional risks to families, especially vulnerable children. Pesticide exposure has been linked to nausea, respiratory distress, neurological impairment, and endocrine disruption, underscoring the need for effective monitoring in both occupational and domestic settings. Conventional analytical methods are costly, require trained personnel, and rely on bulky instruments, limiting their suitability for rapid, on-site screening. Paper-based microfluidic devices have recently emerged as low-cost, portable tools for environmental monitoring, capable of integrating colorimetric enzyme assays on disposable platforms. Yet, the most current systems detect only a single pesticide class, limiting their applicability to complex real-world mixtures. To address this, we developed a dual-enzyme microfluidic device for simultaneous colorimetric screening of representative organophosphate and dithiocarbamate pesticides dichlorvos and ziram, respectively. The system is simple (two steps), low-cost (<$1/test), and user-friendly, enabling rapid field deployment and citizen-based monitoring. Detection limits of 0.15 ppm for dichlorvos and 0.02 ppm for ziram enable environmentally relevant quantification. Testing spiked pesticide residues on leather, denim, and cotton substrates yielded recovery rates of 51-148% for dichlorvos and 29-84% for ziram, demonstrating suitability for monitoring residues on common clothing materials. This dual-enzyme platform provides a practical advance toward accessible, multi-target pesticide exposure monitoring across occupational and household settings.