We present a centrifugal process for the extraction of plasma from sediment by a decanting structure, terminating with metered plasma which is readily available for subsequent on-disk processing. Our technique supplies 2 microl plasma from 5 microl of whole blood at moderate spinning frequencies of 40 Hz within 20 s, only. The residual cell concentration in the purified plasma amounts to less than 0.11%, independent of the frequency of rotation. A capillary duct connects the extracted plasma to subsequent on-disk processing units.

We present a novel, cost-efficient process chain for fast tooling and small-lot replication of high-quality, multi-scale microfluidic polymer chips within less than 5 days. The fabrication chain starts with a primary master which is made by well-established cleanroom processes such as DRIE or negative SU-8 resist based surface micromachining. The formation of undercuts in the master which would complicate demolding is carefully avoided. Secondary PDMS masters or epoxy-based masters which are more suitable for common polymer replication schemes such as soft-embossing, hot-embossing or injection molding are subsequently cast from the primary masters. The polymer replica are mainly made of COC and show excellent fidelity with the conventionally micromachined master while displaying no degeneration, even after more than 200 cycles. The use of other polymers such as PMMA is also possible. The process chain further includes surface modification techniques for overall, long-term stable hydrophilic coatings and for local hydrophobic patches as well as a durable sealing based on thermal bonding.

In this paper, we present a novel and fully integrated centrifugal microfluidic "lab-on-a-disk" for rapid colorimetric assays in human whole blood. All essential steps comprising blood sampling, metering, plasma extraction and the final optical detection are conducted within t=150 s in passive, globally hydrophilized structures which obviate the need for intricate local hydrophobic surface patterning. Our technology features a plasma extraction structure (V=500 nL, CV<5%) where the purified plasma (cRBC<0.11%) is centrifugally separated, metered by an overflow and subsequently extracted by a siphon-based principle through a hydrophilic extraction channel into the detection chamber.

We present a novel microfluidic concept to enable a fast colorimetric alcohol assay from a single droplet of whole blood. The reduced turn-around time of 150 seconds is, on the one hand, achieved by a full process integration including metering, mixing with reagents, and sedimentation of cellular constituents. On the other hand, our novel total internal reflection (TIR) scheme allows to monitor the increase of the absorbance values in real-time. Thus, the saturation values can be predicted accurately based on an extrapolation of real-time measurements acquired during a 100 second initial period of rotation. Additionally, we present a metering structure to define nanolitre sample volumes at a coefficient of variation (CV) below 5%.

This work presents a novel flow switch for centrifugal microfluidic platforms which is solely controlled by the Coriolis pseudo force. This Coriolis switch consists of an inverse Y-structure with one common upstream channel and two symmetric outlets on a rotating disk. Above a certain threshold frequency, the Coriolis force becomes dominant that the entire flow is diverted into one of the outlets which is selected by the direction of rotation. The threshold frequency has been measured to be 350 rad s(-1)(approximately 55.7 Hz) for a channel width of 360 microm and a depth of 125 microm. The results are supported by extensive CFD simulations.