  We have implemented a multi-functional optofluidic sensor that can monitor
changes in the refractive index and pressure of biofluid simultaneously and can
detect free-solution molecular interaction in-situ. In this paper, we
demonstrate two major improvements of this sensor proven by both simulation and
experiments. One improvement is the broader measurement range of refractive
index by making the diffraction grating with high-index polymer. The other
improvement is the separation of refractive index sensing from opacity sensing
by using the relative power ratio of diffraction orders. This simple, compact
and low-cost multi-functional optofluidic sensor has the potential to be used
for in-situ biofluid monitoring.
