Microfluidics

Electronics Repair Manuals

Schematic Diagrams and Service Manuals

Get Instant Access

One of the challenges in multiplexing is how to functionalize individual cantilevers. Some researchers have achieved this by inserting cantilevers to microcapillary arrays separately [3, 19]. While this is acceptable for 1D arrays, such an approach is difficult to implement for 2D arrays. Integrating microfluidic chambers with cantilevers provides physical separation for cantilevers thus a direct means for multiplexed experiments. Figure 2.6 illustrates a microfluidic reaction chamber comprised cantilevers, silicon substrate and glass cap [37]. Each such reaction well contains a large fluidic inlet (called big I/O) and two small fluidic outlets (called small I/O). The small I/O is designed to prevent vapor bubbles to be trapped, such that when a fluid sample is injected into the big I/O the gas was ejected through the small I/O's. To effectively combat the inaccuracies arising from sensor drift and fabrication variations between sensors, the design also includes multiple cantilevers per reaction chamber, each of which received the same analytes at all stages of an experiment. The response from all the sensors in a given reaction well

Light beam

FIGURE 2.6. Schematic diagrams of fluidic design (side view of a bonded reaction well and top view of the Si chip). A single reaction well containing fluidic inlets and outlets in the silicon chip, multiple cantilevers, and the transparent glass/PDMS cover for the laser beam to be used for measuring cantilever deflection.

Light beam

FIGURE 2.6. Schematic diagrams of fluidic design (side view of a bonded reaction well and top view of the Si chip). A single reaction well containing fluidic inlets and outlets in the silicon chip, multiple cantilevers, and the transparent glass/PDMS cover for the laser beam to be used for measuring cantilever deflection.

could then be used to obtain a more statistically relevant response for each well. In order to use the cantilever array chip as a multiplexed sensor array, each reaction well must be physically separated from the neighboring wells. This is achieved using a pyrex substrate that is patterned and etched to produce the reaction well, and bonded to the silicon chip. The bonding is accomplished using an adhesive stamping technique [25]. The fabrication process for the cantilever array chip utilizes conventional microelectromechanical systems (MEMS) fabrication including bulk and surface micromachining, which are described in detail by Yue et al. [36, 37]. The yield (percent of cantilevers on each chip surviving the fabrication process) achieved from this fabrication process ranged from 95-98%. Figure 2.7 shows optical and electron micrographs of the cantilever array chip.

Was this article helpful?

0 0

Post a comment