Elastomeric 2D Grating and Hemispherical Optofluidic Chamber for Multifunctional Fluidic Sensing

We present an optofluidic sensor based on an elastomeric two-dimensional (2D) grating integrated inside a hemispherical fluid chamber. Laser beam is diffracted before (reflection) and after (transmission) going through the grating and liquid in the dome chamber. The sensing mechanism is investigated and simulated with a finite difference time domain (FDTD) based electromagnetic (EM) method. For experiment, by analyzing the size, power and shape of the 2D diffraction patterns, we can retrieve multiple parameters of the liquid including the refractive index, pressure and opacity with high sensitivity. We demonstrate that glucose concentration can be monitored when mixed in different concentrated phosphate buffered saline (PBS) solution. The free-solution binding of bovine serum albumin (BSA) and anti-BSA IgG is detected with this optical sensor. This low-cost, multifunctional and reliable optofluidic sensor has the potential to be used as monitor of biofluid such as blood in hemodialysis.