Fig. 5: Reliability test of l-proline sensing.
From: High-sensitivity nanophotonic sensors with passive trapping of analyte molecules in hot spots
a, b Reflection spectra of repeated sensing experiments for 1 μg/mL proline solution by using a sensor with 200 nm wide nano-trenches in a and a sensor with 450 nm wide nano-trenches in b. The black dot-dashed curve in each graph is the reflection spectra of the bare device. c Reflection spectra measured at the four quadrants of the sensor in b after two 1 μL droplets of 0.2 μg/mL proline solution were applied. Each quadrant (A, B, C, or D) has an area of ~150 μm by 150 μm. d Representative SEM images showing the non-uniform proline precipitate distribution in quadrant B (top) and quadrant D (bottom). The SEM images are taken at a view angle of 45° of the device surface normal. The structures and color changes near the lower edge of the Al ribbon in each image correspond to the proline precipitate. The scale bar is 400 nm
