In point-of-care (POC) molecular diagnostics, inhibitors from liquid residue in a microfluidic chip fundamentally limit the performance of automated nucleic acid extraction (NAE). In response to this challenge, a multifaceted strategy has been developed. We engineered a novel U-shaped microchannel via injection molding, which inherently reduces liquid retention by 2-fold over conventional square channels. Critically, we identified that surfactants, while essential for lysis, were a major source of undesired liquid retention; a simple water-rinse stage was developed to counteract this effect, further decreasing the residue by 5-fold. Process efficiency was radically enhanced by integrating ultrasonic excitation, achieving both a sample-to-pure-NA time of just 5 min and NA recovery rates in microchips comparable to conventional extraction methods. These physical, chemical, and process-level innovations were consolidated into the universal automated nucleic acid extraction (UNEX) system. Featuring lyophilized, shelf-stable reagents for cold-chain independence, the UNEX system is a truly automated, sample-in-to-result-out platform. When benchmarked against traditional methods using various clinical samples, UNEX exhibited exceptional precision (CV R2 > 0.99). Our work provides a robust, field-deployable NAE solution, proving that a holistic approach (combining optimized channel geometry with intelligent fluidic protocols and energy-assisted elution) is key to unlocking the full potential of LOC technology in diagnostics.
Chen et al. (2026) studied this question.