Aliquoting on the centrifugal microfluidic platform based on centrifugo-pneumatic valves
We present a new method for aliquoting liquids on the centrifugal microfluidic platform. Aliquoting is an essential unit operation to perform multiple parallel assays (“geometric multiplexing”) from one individual sample, such as genotyping by real-time polymerase chain reactions (PCR), or homogeneous immunoassay panels. Our method is a two-stage process with an initial metering phase and a subsequent transport phase initiated by switching a centrifugo-pneumatic valve. The method enables aliquoting liquids into completely separated reaction cavities. It includes precise metering that is independent on the volume of pre-stored reagents in the receiving cavities. It further excludes any cross-contamination between the receiving cavities. We characterized the performance for prototypes fabricated by three different technologies: micro-milling, thermoforming of foils, and injection molding. An initial volume of ~90 μl was split into 8 aliquots of 10 μl volume each plus a waste reservoir on a thermoformed foil disk resulting in a coefficient of variation (CV) of the metered volumes of 3.6%. A similar volume of ~105 μl was split into 16 aliquots of 6 μl volume each on micro-milled and injection-molded disks and the corresponding CVs were 2.8 and 2.2%, respectively. Thus, the compatibility of the novel aliquoting structure to the aforementioned prototyping and production technologies is demonstrated. Additionally, the important question of achievable volume precision of the aliquoting structure with respect to the production tolerances inherent to each of these production technologies is addressed experimentally and theoretically. The new method is amenable to low cost mass production, since it does not require any post-replication surface modifications like hydrophobic patches.
KeywordsLab-on-a-chip Centrifugal microfluidics Aliquoting Multiplexing PCR Pneumatic
The authors gratefully acknowledge financial support by the German Federal Ministry of Education and Research (project Zentrilab, grant No. 16SV2347). Part of this work was funded by the Federal Ministry of Education and Research (BMBF) under the Research Programme for Civil Security of the German Federal Government as part of the High-Tech Strategy for Germany (project SONDE, grant No. 3N10116). The authors also gratefully acknowledge financial support by the European Union (project MagRSA, contract No. 037957).
- Andersson P, Ekstrand G (2007) Retaining microfluidic microcavity and other microfluidic structures. (US7300199)Google Scholar
- Burtis CA, Anderson NG, Mailen JC, Scott CD, Tiffany TO, Johnson WF (1972) Development of a miniature fast analyzer. Clin Chem 18(8):753–761Google Scholar
- Cho YK, Lee JG, Park JM, Lee BS, Lee Y (2008) Lab-on-a-disc for simultaneous analysis of blood chemistry and immunoassay. In: Proceedings of 12th international conference on miniaturized systems for chemistry and life sciences (μTAs)Google Scholar
- ESI-Group (2007) CFD-ACE+ 2007. http://www.esi-group.com/
- Focke M, Stumpf F, Faltin B, Reith P, Bamarni D, Wadle S, Müller C, Reinecke H, Schrenzel J, Francois P, Mark D, Roth G, Zengerle R, von Stetten F (2010) Microstructuring of polymer films for highly sensitive genotyping by real-time PCR on a centrifugal microfluidic platform. Lab Chip 10(19):2519–2526. doi: 10.1039/C004954A CrossRefGoogle Scholar
- Lutz S, Weber P, Focke M, Faltin B, Hoffmann J, Müller C, Mark D, Roth G, Munday P, Armes NA, Piepenburg O, Zengerle R, von Stetten F (2009) Microfluidic lab-on-a-foil for nucleic acid analysis based on isothermal recombinase polymerase amplification of DNA. Lab Chip 10:887–893. doi: 10.1039/B921140C CrossRefGoogle Scholar
- Rubenstein KE, Schneider RS, Ullman EF (1972) “Homogeneous” enzyme immunoassay. A new immunochemical technique. Biochem Biophys Res Commun 47(4):846–851. doi: 10.1016/0006-291X(72)90570-0
- Schembri CT, Ostoich V, Lingane PJ, Burd TL, Buhl SN (1992) Portable simultaneous multiple analyte whole-blood analyzer for point-of-care testing. Clin Chem 38(9):1665–1670Google Scholar