Waterborne pathogens remain a major public health challenge because of their association with gastrointestinal illness and fatal outcomes. Their detection requires rapid, specific, portable, easy-to-use, and reliable platforms, making microfluidic biosensing a promising strategy. Here, we present a centrifugal microfluidic device that, guided by lumped-element computational modeling, integrates a passive elastic membrane-assisted reciprocating mechanism with a PAMAM dendrimer-aptamer-functionalized PDMS interface for Escherichia coli O157:H7 detection. The model guided device design and evaluated the effects of membrane and fluidic parameters on reciprocation, showing good agreement with experimental liquid reciprocation at 30 rpm/s, with a maximum error of 6.76% and a 1.25 mm deviation in liquid-front position. FTIR analysis supported stepwise PDMS modification with APTMS, PAMAM dendrimers, and DNA aptamers. Using mRuby-expressing E. coli O157:H7 as a fluorescent whole-cell model, bacterial capture increased at lower angular acceleration and with repeated reciprocation. The highest fluorescence response occurred at 1 rpm/s after three cycles, with signal intensity strongly correlated with cycle number (R² = 0.997). The platform detected E. coli O157:H7 with a calculated limit of detection of 8.14 × 10³ CFU/mL. These results demonstrate reciprocation-enhanced whole-cell capture and support future pathogen detection applications in water-quality monitoring.
