On-Site Pooled Screening of Genetically Modified Crops via an Integrated Centrifugal Digital Microfluidic Platform

The identification of genetically modified crops is extensively employed across diverse agricultural testing scenarios, especially at customs and ports. However, the current methods that rely on laboratory settings are unable to perform nucleic acid detection in a portable, rapid, and resource-efficient manner, especially when dealing with huge amounts of crops. Although individual microfluidic modules have been reported, an integrated platform that fulfils the demands of portable quantitative detection is still missing. In this study, we propose a point-of-care testing platform that enables the complete closed-loop workflow, tailored to the practical demands of import/export inspection at customs. The platform integrates magnetic bead-based nucleic acid extraction, Tesla valve-based micromixing, and centrifugal microdroplet generation on a microfluidic chip, achieving fully integrated sample processing from crude lysate to digital LAMP detection. This platform enables absolute quantitative detection of specific genetically modified maize samples within 45 min, achieving a limit of detection (LOD) as low as 1.6 copies/μL. Identifications of individual samples and pooled samples extracted from a large quantity of crops are verified with a strong linear correlation (higher than 0.997) compared to the commercial Nanodrop method. In addition, the high sensitivity and quantitative accuracy of this platform enable the enforcement of a pooled testing strategy, which significantly reduces the time and cost for high-throughput screening. The proposed platform shows significant potential for on-site deployment at various points, including customs ports, field sites, processing facilities, and markets, thereby facilitating comprehensive "farm-to-table" supply chain monitoring.