Self-aligned plasmonic-nanofluidic system by continuous laser manufacturing

The plasmonic−nanofluidic system incorporates the nanoplasmonic metal structure with nanofluidic channel, exhibiting improved performance in optofluidic sensing. However, the device requires sophisticated nanofabrication, which is the main bottleneck for the practical applications. Here, we proposed a self-aligned plasmonic-nanofluidic device, in which both nanochannel and plasmonic nanostructures are readily fabricated and self-aligned by using only one step of direct laser writing. Specifically, we use a single gold subwavelength nanochannel to simultaneously apply both spatial confinement and plasmonic enhancement. Furthermore, instead of using an ultrafast laser, we demonstrate the feasibility of drilling nanochannels on suspended substrate using continuous lasers. In contrast to conventional plasmonic nanochannels with plasmonic enhancement only under transverse magnetic (TM) mode laser, our sample presents obvious plasmonic effects under both TM and transverse electric mode lasers, which is beneficial for improving the overall signal. Our method has great potential in the widespread adoption of the plasmonic-nanofluidic system.