The fabrication and experimental testing of polydimethylsiloxane (PDMS) optofluidic biochips with integrated solidcore
polyepoxyacrylate (PEA). optical waveguides is described. The biochips were replicated from silicon masters made
by 50-μm-deep reactive ion etching. Each biochip contained three 70-μm-wide solid-core waveguides focused on the
middle section of a 50-μm-wide, Y-shaped, microchannel. Electroosmotic flow with a voltage range of 50 to 300 volts
was used to drive fluorescent beads in the microfluidic channel. Using two excitation lasers at 532nm and 635nm with
distinct modulation frequencies, two species of microparticles with different fluorophores were identified by capturing
the fluorescence in a photomultiplier tube and analyzing the signal with a windowed Fourier transform analysis technique.
This paper describes the development of multi-level lab-on-a-chip devices that use integrated optics to reduce the size and cost of portable dual-function analysis systems. Silicon/polymer and all-polymer devices were fabricated that have separate optics and fluidics layers that are bonded together. The optical layer has hollow v-groove waveguides in anisotropically etched silicon or in polymethylmethacrylate (PMMA) that is replicated from the silicon in a two-step replication procedure using polyvinyl alcohol (PVA) as an intermediate negative replica. Light from hollow v-groove waveguides in the optical layer is coupled to the fluidic layer by reflection from metallized reflective planes. The fluidic layer is constructed of polydimethylsiloxane (PDMS) in a two-step positive replication procedure from a micromachined glass master. A thin intermediate PMMA layer with reflective metal strips seals both the hollow optical waveguides and the PDMS microchannels.
In this paper, we propose a novel lab-on-a-chip with an integrated spectrometer that uses a single, sensitive off-chip photomultiplier tube (PMT) for detection and the motion of fluorescent cells or other analytes in a microchannel to generate a signal that is equivalent to a time-dependent scan of the spectrum. The excitation light from off-chip lasers is carried to the channel by integrated waveguides and integrated lenses capture and focus the fluorescence into an optical waveguide that carries the fluorescent to the chip edge and into the fiber-coupled PMT. All elements can be fabricated in a single transparent layer of SU-8 or another polymer using standard microfabrication methods.