Fig. 3.

Spectroscopic performance of probe in comparison to bare fibers. a) Detection of white light through bare fibers (red) and through each lensed fiber (blue), showing identical spectral shapes. Data were offset for comparison. b) White light reflectance spectrum from varied materials. c and d) Laser excitation of 10 µM resorufin with lensed and unlensed fibers immersed in the bulk solution (c) and in microfluidic channels through a 100 µm PDMS coverslip (d). The microfabricated optics’ focusing capability offset the reduced light transmission and resulted in stronger fluorescence on chip.