Nanoporous Elements in Microfluidics for Multiscale Manipulation of Bioparticles

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 7; no. 8; pp. 1061 - 1067
• Main Authors: Chen, Grace D., Fachin, Fabio, Fernandez-Suarez, Marta, Wardle, Brian L., Toner, Mehmet
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 18.04.2011; WILEY‐VCH Verlag
• Subjects: carbon nanotubes; filters; lab-on-a-chip devices; microfluidics; Microfluidics - methods; Nanoparticles - chemistry; nanoporous materials; Particle Size; Permeability; Porosity
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.201002076

Solid materials, such as silicon, glass, and polymers, dominate as structural elements in microsystems including microfluidics. Porous elements have been limited to membranes sandwiched between microchannel layers or polymer monoliths. This paper reports the use of micropatterned carbon‐nanotube forests confined inside microfluidic channels for mechanically and/or chemically capturing particles ranging over three orders of magnitude in size. Nanoparticles below the internanotube spacing (80 nm) of the forest can penetrate inside the forest and interact with the large surface area created by individual nanotubes. For larger particles (>80 nm), the ultrahigh porosity of the nanotube elements reduces the fluid boundary layer and enhances particle–structure interactions on the outer surface of the patterned nanoporous elements. Specific biomolecular recognition is demonstrated using cells (≈10 μm), bacteria (≈1 μm), and viral‐sized particles (≈40 nm) using both effects. This technology can provide unprecedented control of bioseparation processes to access bioparticles of interest, opening new pathways for both research and point‐of‐care diagnostics. Patterned carbon‐nanotube forests as nanoporous elements in microfluidics are introduced for the enhancement of microscale bioseparation. The ultrahigh porosity of the forest enhances particle–surface interactions both for particles small enough to penetrate inside the forest and larger particles that flow around the forest. Mechanical and/or chemical capture of bioparticles ranging over three orders of magnitude in size is demonstrated.