Silicon nanopillar-forest based microfluidic surface-enhanced Raman scattering devices

We report a novel microfluidic surface-enhanced Raman scattering (SERS) device, which is achieved by bonding a polydimethylsiloxane cap with a microchannel structure onto an SERS-active substrate composed of noble-metal covered silicon nanopillar forests. The silicon nanopillar forests are fabricated by using nanomaterial dots, which are introduced in oxygen-plasma bombardment of photoresist, as etching masks. Analytes are uniformly distributed in the nanopillar forests by flowing through the microchannels, and thus higher measurement repeatability is obtained compared with regular open SERS-active substrates. Moreover, the enhancement factor (EF) of the devices can be self-calibrated by utilizing the flat metal areas beside the forests as references. Accordingly, such SERS devices have an EF on the order of 5.2×10⁵. Meanwhile, the devices can reduce the measurement time from several hours to about 10 minutes.