Jump to main content
Jump to site search


Asymmetric nanofluidic grating detector for differential refractive index measurement and biosensing

Author affiliations

Abstract

Measuring small changes in refractive index can provide both sensitive and contactless information on molecule concentration or process conditions for a wide range of applications. However, refractive index measurements are easily perturbed by non-specific background signals, such as temperature changes or non-specific binding. Here, we present an optofluidic device for measuring refractive index with direct background subtraction within a single measurement. The device is comprised of two interdigitated arrays of nanofluidic channels designed to form an optical grating. Optical path differences between the two sets of channels can be measured directly via an intensity ratio within the diffraction pattern that forms when the grating is illuminated by a collimated laser beam. Our results show that no calibration or biasing is required if the unit cell of the grating is designed with an appropriate built-in asymmetry. In proof-of-concept experiments we attained a noise level equivalent to ∼10−5 refractive index units (30 Hz sampling rate, 4 min measurement interval). Furthermore, we show that the accumulation of biomolecules on the surface of the nanochannels can be measured in real-time. Because of its simplicity and robustness, we expect that this inherently differential measurement concept will find many applications in ultra-low volume analytical systems, biosensors, and portable devices.

Graphical abstract: Asymmetric nanofluidic grating detector for differential refractive index measurement and biosensing

Back to tab navigation

Supplementary files

Publication details

The article was received on 30 Aug 2017, accepted on 23 Oct 2017 and first published on 24 Oct 2017


Article type: Paper
DOI: 10.1039/C7LC00929A
Citation: Lab Chip, 2017, Advance Article
  • Open access: Creative Commons BY license
  •   Request permissions

    Asymmetric nanofluidic grating detector for differential refractive index measurement and biosensing

    F. Purr, M. Bassu, R. D. Lowe, B. Thürmann, A. Dietzel and T. P. Burg, Lab Chip, 2017, Advance Article , DOI: 10.1039/C7LC00929A

    This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements