Sapphire-GaN-based planar integrated free-space optical system

Integrated optofluidic system for monitoring particle mass concentrations based on planar emitter-receiver units

We demonstrate an integrated optofluidic system for monitoring the particle mass concentration and the Sauter mean diameter of polydisperse flowing suspensions of water and standardized test dust. For optimum integration, a planar emitter-receiver unit is developed and fabricated on Si technology. A vertical cavity surface emitting laser at 850 nm serves as light source, and monolithically integrated segmented photodiodes detect both the attenuation of the primary light beam and the scattered light. The optical system is integrated into a planar transparent polymethylmethacrylate substrate by micromilling of an optical freeform surface and electron beam evaporation of reflective layers following the concept of planar integrated free-space optical systems. We are able to detect 1 mg/L of the standards ISO 12103-A2 (fine test dust), -A3 (medium test dust), and -A4 (coarse test dust) and to determine the Sauter mean diameter of the particle size distribution.

Single-step replication of a highly integrated PDMS optofluidic analysis system

Micromilling is a promising technology for the fabrication of surface profiles with optical quality. We present a highly integrated optofluidic system made of polydimethylsiloxane (PDMS). The system is replicated in a single-step process from a micromilled polymethyl methacrylate master mold. It already includes the reservoirs, the channel system, as well as the optical interconnect surfaces for high numerical aperture objectives. We demonstrate the potential of this approach by laser-based three-dimensional optical manipulation within the replicated system. To our knowledge, this is the first time that a PDMS membrane is used as a well-defined channel wall for an optical trapping setup.