A novel gas sensor based on tunneling-field-ionization on whisker-covered gold nanowires

Ramin Banan Sadeghian, Mojtaba Kahrizi

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


Typical gas ionization sensors (GISs) work by finger-printing the ionization breakdown voltages of the gases to be identified. In this work, we developed a GIS that operates by field-ionizing the unknown gas at exceptionally low voltages. The resultant field-ion current-voltage (I - V) characteristic was then used to identify the gas. Freestanding gold nanowires (AuNW), terminated with nanoscale whisker-like features, were employed as field-amplifiers to reduce the field ionization threshold voltages. Synthesis of the AuNWs was carried out by the template-assisted technique accompanied by two alterations: 1) polystyrene (PS) microspheres were incorporated to reduce the compactness of the pores, thus prevent the nanostructures from collapse, and 2) the template was impregnated by HAuCl4 to form gold nanowhiskers during the electrochemical nucleation of AuNWs. The sensor was tested in three elemental gases: Ar, N2 and He, in a pressure range of 0.01 < P < 100 torr. Each gas demonstrated a distinctive I - V curve, particularly in the field-limited regime. The threshold ionization voltages ranged from 1 to 10 V, almost three orders of magnitude lower than the voltages used in field-ion-microscopy. The low-voltage field ionization was attributed to the field-amplifying nanoscale whiskers on the AuNW tips, as well as the presence of residual amorphous alumina with semiconducting characteristics, due to incomplete removal of the porous anodized alumina (PAA) template.

Original languageEnglish
Pages (from-to)161-169
Number of pages9
JournalIEEE Sensors Journal
Issue number2
Publication statusPublished - 2008 Feb
Externally publishedYes


  • Field enhancement
  • Field ionization
  • Gas sensor
  • Gold nanowires

ASJC Scopus subject areas

  • Instrumentation
  • Electrical and Electronic Engineering


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