Single entity resolution valving of nanoscopic species in liquids


Investigating biological and synthetic nanoscopic species in liquids, at the ultimate resolution of single entity, is important in diverse fields1,2,3,4,5. Progress has been made6,7,8,9,10, but significant barriers need to be overcome such as the need for intense fields, the lack of versatility in operating conditions and the limited functionality in solutions of high ionic strength for biological applications. Here, we demonstrate switchable electrokinetic nanovalving able to confine and guide single nano-objects, including macromolecules, with sizes down to around 10 nanometres, in a lab-on-chip environment. The nanovalves are based on spatiotemporal tailoring of the potential energy landscape of nano-objects using an electric field, modulated collaboratively by wall nanotopography and by embedded electrodes in a nanochannel system. We combine nanovalves to isolate single entities from an ensemble, and demonstrate their guiding, confining, releasing and sorting. We show on-demand motion control of single immunoglobulin G molecules, quantum dots, adenoviruses, lipid vesicles, dielectric and metallic particles, suspended in electrolytes with a broad range of ionic strengths, up to biological levels. Such systems can enable nanofluidic, large-scale integration and individual handling of multiple entities in applications ranging from single species characterization and screening to in situ chemical or biochemical synthesis in continuous on-chip processes.

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Fig. 1: Concept and use of electrokinetic nanovalves.
Fig. 2: Guiding, confining and releasing adenoviruses, quantum dots and immunoglobulin G antibodies.
Fig. 3: Lateral displacement of polystyrene bead and adenovirus in a.c. mode.
Fig. 4: Investigated nanoscale species and corresponding conditions.


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We appreciate the support from Binnig Rohrer Nanotechnology Center of ETH Zurich and IBM Zurich. We thank M. K. Tiwari for his support in the very beginning phase of work related to trapping of nanoscale matter in channels; Y. Federoshyn for electron-beam lithography exposures, H. Ewers for providing the lipid vesicle solutions; F. Robotti, S. Bottan, M. Bergert, C. Giampietro and A. Ferrari for help with biological species; J. Marschewski for electrode characterization; A. Renn and T. Schutzius for fruitful discussions; and J. Vidic for technical support. We acknowledge the help of M. Wöhrwag and P. Gschwend, for performing some analysis at the early stage of the project and the Particle Technology Laboratory (PTL) at ETH Zurich for providing access to their zetasizer instrument. The work was partially supported by the Swiss National Science Foundation under grants 200021_162855 and 310030B_160316.

Author information




P.E., H.E. and D.P. conceived the research, designed the experiments, analysed data and wrote the manuscript. P.E. designed and fabricated the devices and performed theoretical analysis. H.E. designed and implemented the optical imaging systems. P.E., C.H. and P.M. performed experiments. M.S. and U.G. provided adenoviruses and expertise on viral particles. H.E. and D.P. supervised all aspects of the project. All authors proofread the manuscript.

Corresponding authors

Correspondence to Hadi Eghlidi or Dimos Poulikakos.

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The authors declare no competing interests.

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Supplementary information

Supplementary Information

Supplementary Text, Supplementary Figures 1–13 and Supplementary References

Supplementary Video 1

Guiding, confining and releasing of an adenovirus (diameter 90 nm) in a trap-in-channel structure

Supplementary Video 2

Guiding, confining and releasing of a 100-nm gold particle in a trap-in-channel structure

Supplementary Video 3

Sorting single QDs in a trap-in-junction structure

Supplementary Video 4

Sorting single IgG molecules in a trap-in-junction structure

Supplementary Video 5

Sorting single adenoviruses in a trap-in-junction structure

Supplementary Video 6

Guiding, confining and releasing of a 100-nm gold particle in a trap-in-junction structure

Supplementary Video 7

On-demand trapping of two fluorescent beads (100 nm diameter in a.c. mode)

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Eberle, P., Höller, C., Müller, P. et al. Single entity resolution valving of nanoscopic species in liquids. Nature Nanotech 13, 578–582 (2018).

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