Single-step centrifugal hematocrit determination on a 10-$ processing device
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We present a novel concept to process human blood on a spinning polymer disk for the determination of the hematocrit level by simple visual inspection. The microfluidic disk which is spun by a macroscopic drive unit features an upstream metering structure and a downstream blind channel where the centrifugally enforced sedimentation of the blood is performed. The bubble-free priming of the blind channel is governed by centrifugally assisted capillary filling along the sloped hydrophilic side-wall and the lid as well as the special shape of the dead end of the two-layer channel. The hematocrit is indicated at the sharp phase boundary between the plasma and the segregated cellular pellet on a disk-imprinted calibrated scale. This way, we conduct the hematocrit determination of human blood within 5 min at a high degree of linearity (R 2 = 0.999) and at a high accuracy (CV = 4.7%) spanning over the physiological to pathological working range. As all processing steps including the priming, the metering to a defined volume as well as the centrifugation are executed automatically during rotation, the concept is successfully demonstrated in a conventional PC-CDROM drive while delivering the same performance (R 2 = 0.999, CV = 4.3%).
KeywordsBubble-free priming Hematocrit All-in-one CDROM Centrifugal microfluidics
The authors are grateful to the partial financial support by the German federal state of Baden-Württemberg (contract number 24-720.431-1-7/2).
- B. Bull, J. Koepke, E. Simson, O. van Assendelft, Procedure for Determining Packed Cell Volume by the Microhematocrit Method; Approved Standard—3rd edn. (Clinical and Laboratory Standards Institute (NCCLS), Villanova, USA, 1994)Google Scholar
- COC—Cyclic olefin copolymer (Topas®), www.ticona.com, accessed 2007
- Diaglobal HCT 142 Hematocrit Turbidimetric Test, Diaglobal GmbH, www.diaglobal.de, accessed 2007
- F. Goldschmidtboeing, P. Woias, Strategies for void-free liquid-filling of micro cavities. Proceedings of transducers ‘05 conference (IEEE, Seoul, Korea, 2005), pp. 1561–1564Google Scholar
- Hermle Microhematocrit Test, Hermle Labortechnik GmbH, Wehingen, Germany, www.hermle-labortechnik.de, accessed 2007
- M. Madou, G. Kellogg, LabCD: a centrifuge-based platform for diagnostics. Proceedings of the international SPIE conference, vol. 3259 (SPIE, San Jose, 1998), pp. 80–93Google Scholar
- M.R. McNeely, M.K. Spute, N.A. Tusneen, A.R. Oliphant, Hydrophobic microfluidics. Proceedings of the international SPIE conference, vol. 3877 (SPIE, Santa Clara, 1999), pp. 210–220Google Scholar
- L. Riegger, M. Grumann, T. Brefka, J. Steigert, C.P. Steinert, T. Brenner, R. Zengerle, J. Ducrée, Bubble-free priming of blind capillaries for high-accuracy centrifugal hematocrit measurements. Proceedings of μTAS '05 conference (TRF, Boston, 2005), pp. 796–798Google Scholar
- C.P. Steinert, H. Sandmaier, M. Daub, B. de Heij, R. Zengerle, Bubble free priming of blind channels. Proceedings of IEEE-MEMS 2004 (IEEE, Maastricht, The Netherlands, 2004), pp. 224–228Google Scholar
- A. van den Berg, E. Oosterbroek, Micro Total Analysis Systems. (Elsevier, Amsterdam, The Netherlands, 2003)Google Scholar