文摘
A six-channel microfluidic immunoassay device with ascanned fluorescence detection system is described. Sixindependent mixing, reaction, and separation manifoldsare integrated within one microfluidic wafer, along withtwo optical alignment channels. The manifolds are operated simultaneously and data are acquired using a single-point fluorescence detector with a galvano-scanner to stepbetween separation channels. A detection limit of 30 pMwas obtained for fluorescein with the scanning detector,using a 7.1-Hz sampling rate for each of the reactionmanifolds and alignment channels (57-Hz overall sampling rate). Simultaneous direct immunoassays for ovalbumin and for anti-estradiol were performed within themicrofluidic device. Mixing, reaction, and separationcould be performed within 60 s in all cases and within30 s under optimized conditions. Simultaneous calibration and analysis could be performed with calibrant inseveral manifolds and sample in the other manifolds,allowing a complete immunoassay to be run within 30 s.Careful chip conditioning with methanol, water, and 0.1M NaOH resulted in peak height RSD values of 3-8% (N= 5 or 6), allowing for cross-channel calibration. The limitof detection (LOD) for an anti-estradial assay obtained inany single channel was 4.3 nM. The LOD for the cross-channel calibration was 6.4 nM. Factors influencing chipand detection system design and performance are discussed in detail.