Organic thin film transistors as selective sensing platforms for Hg2+ ions and the amino acid cysteine

Mohan Ramesh, Hong-Cheu Lin*, Chih Wei Chu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


In this short communication we report a sensor for divalent mercuric (Hg2+) ions that we constructed from a perylene bisimide (PBI)-based organic thin film transistor. We improved the performance of the n-channel device by positioning N,N'-dioctyl-3,4,9,10-perylenedicarboximide between the dielectric and the active layer (PBI), increasing the electron mobility (μ) from 0.002 to 0.25±0.04cm2V-1s-1 and enhancing the on/off ratio (Ion/Ioff) by two orders of magnitude (from 102 to 104). Based on a "thymine-Hg2+-thymine" mechanism and monitoring the shift in the threshold voltage (Vth), we used this transistor to discriminate Hg2+ ions from mixed ion solutions and it extended to different concentration Hg2+ solutions (from 50 to 350μM). By monitoring the shifts in drain current (IDS) and Vth, we also used this bilayer device as a sensor for cysteine, a thiol-containing amino acid; the selective detection of cysteine was accompanied by a red shift in the fluorescence maximum of PBI, from 532 to 537nm.

Original languageEnglish
Pages (from-to)76-79
Number of pages4
JournalBiosensors and Bioelectronics
Issue number1
StatePublished - 5 Apr 2013


  • Amino acid
  • Mercuric ion
  • Metal ion sensor
  • Perylene bisimide
  • Thin film transistor

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