Influences of Nanoparticle Loading in Paper-SERS Sensors

We fabricate SERS sensors by inkjet printing and demonstrate that their SERS response correlates with their diffuse reflectance characteristics. Using a modified commercial inkjet-printer, SERS sensors are prepared with multiple printing passes. Performances of the printed sensors only become noticeable after 5 printing passes as observed in both SERS and diffuse reflectance measurements. This suggests that the simpler diffuse reflectance measurement can be used as an alternative method to characterize and optimize the SERS performance of the printed sensors. Although sensors with a very high number of printing passes exhibit a much stronger SERS response from the benzenethiol reporter molecule, we also noticed a significant increase in the background from blank sensors. This may not be a desirable feature particularly for the detection of weakly bound molecules. Controlling SERS background and attaining a desirable SERS enhancement would need to be balanced in the design of sensors for the end-user's specific need.