Nanoporous waveguide sensor with optimized nanoarchitectures for highly sensitive label-free biosensing

Kazuhiro Hotta, Akira Yamaguchi, Norio Teramae

Research output: Contribution to journalArticlepeer-review

93 Citations (Scopus)


Label-free optical biosensors have attracted much attention, and nanoporous metal-oxide membranes with uniform pore structure and diameter are promising candidates for platforms of label-free optical biosensors. However, development of such sensors with high sensitivity still remains challenging. In this paper, we report on the remarkably enhanced sensitivity of a label-free nanoporous optical waveguide (NPWG) sensor composed of a porous anodic alumina (PAA) waveguiding film and an aluminum cladding film. The enhanced sensitivity was achieved by engineering nanostructures and tuning optical properties of the PAA film. Careful tuning of the porosity, pore density, thickness, and refractive index of the PAA film could significantly improve the sensitivity of the NPWG sensor toward adsorption of bovine serum albumin (BSA) onto the PAA surface, and the optimized sensor responded to the adsorption of BSA with an extraordinarily large red shift (>300 nm) of a waveguide mode due to the large adsorption capacity of the PAA film and the inherently high sensitivity of the waveguide mode. The Fresnel calculations suggested that the potential sensitivity of the NPWG sensor was much higher than that of the conventional surface plasmon resonance (SPR) sensors.

Original languageEnglish
Pages (from-to)1541-1547
Number of pages7
JournalACS Nano
Issue number2
Publication statusPublished - 2012 Feb 28


  • biosensing
  • label-free
  • nanopores
  • optical waveguide sensor
  • porous anodic alumina

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)


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