Ultrafast VCSEL-based plasmonic polymerase chain reaction with real-time label-free amplicon detection for point-of-care diagnostics

Recent progress in microfluidics and optical systems has made enormous impact in the advancement of nucleic acid amplification and detection. However, commercial and currently reported microfluidic PCR devices have not yet found their utilization in point-of-care (POC) applications. This is due to long amplification time, high power requirement, and bulky size of commercial PCR machines or cost-inefficiency, complex fabrication and operation of microfluidic chips. In this work, we present a compact PCR device in which fast amplification is accomplished by photothermal heating of gold nanorods evenly dispersed in PCR reaction by a vertical-cavity surface-emitting laser (VCSEL). This thermocycler offers sub-ten-minute amplification time for 30 thermal cycles with high temperature stability and PCR products comparable to conventional bench-top machines. The proposed device is approximately 100mm×50mm×50mm in size, and its small footprint is obtained by hardware miniaturization. Retaining conventional sample volumes (20μL) makes our device more user-friendly in terms of sample loading and capable of more sensitive amplicon detection for on-site assays. Also, its cost-effectiveness due to disposable AuNRs and inexpensive light source outweigh surface plasmon heating methods utilizing embedded Au films with limited lifetimes and other previously presented plasmonic thermocyclers.