Semi-quantitative design of black phosphorous field-effect transistor sensors for heavy metal ion detection in aqueous media

Jingbo Chang, Haihui Pu, Spencer A. Wells, Keying Shi, Xiaoru Guo, Guihua Zhou, Xiaoyu Sui, Ren Ren, Shun Mao, Yantao Chen, Mark C. Hersam, Junhong Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Two-dimensional (2D) crystalline nanomaterial based field-effect transistor (FET) water sensors are attracting increased attention due to their low cost, portability, rapid response, and high sensitivity to aqueous contaminants. However, a generic model to aid in sensor design by describing direct interactions between metal ions and 2D nanomaterials is lacking. Here, we report a broadly applicable statistical thermodynamics model that describes the behavior of FET sensors (e.g., lower detection limit) by relying only on the ion concentration and intrinsic properties of the sensor material such as band gap and carrier effective mass. Two regimes of the sensing mechanism (charge transfer vs. electrostatic gating) were predicted, depending on the relative size of the Debye screening length in the sensor material and the distance between adsorbed ions. At a lower ion adsorption density, the charge transfer effect is dominant, while the evolution from charge transfer to electrostatic gating effect occurs at a higher adsorption density as the distance between adsorbed ions approaches the Debye length. Owing to its tunable band gap, black phosphorus (BP) nanosheet FET sensors were selected to semi-quantitatively validate the model including the predicted evolution between the two sensing regimes. Among Na+, Mg2+, Zn2+, Cd2+, Pb2+, and Hg2+ ions, BP nanosheet FET sensors were more responsive to Hg2+ ions for probe-free detection. The theoretical lower detection limit of Hg2+ ions can reach 0.1 nM (0.1 fM) in tap (deionized) water.

Original languageEnglish (US)
Pages (from-to)491-502
Number of pages12
JournalMolecular Systems Design and Engineering
Issue number3
StatePublished - Jun 2019

ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Chemical Engineering (miscellaneous)
  • Biomedical Engineering
  • Energy Engineering and Power Technology
  • Process Chemistry and Technology
  • Industrial and Manufacturing Engineering
  • Materials Chemistry


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