Ultrasensitive Molecular Sensors Based on Real-Time Impedance Spectroscopy in Solution-Processed 2D Materials

David C. Moore, Ali Jawaid, Robert Busch, Michael Brothers, Paige Miesle, Adam Miesle, Rahul Rao, Jonghoon Lee, Lucas K. Beagle, Michael Motala, Shay Goff Wallace, Julia R. Downing, Ajit Roy, Christopher Muratore, Mark C. Hersam, Richard Vaia, Steve Kim, Nicholas R. Glavin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Chemical sensors based on solution-processed 2D nanomaterials represent an extremely attractive approach toward scalable and low-cost devices. Through the implementation of real-time impedance spectroscopy and development of a three-element circuit model, redox exfoliated MoS2 nanoflakes demonstrate an ultrasensitive empirical detection limit of NO2 gas at 1 ppb, with an extrapolated ultimate detection limit approaching 63 ppt. This sensor construct reveals a more than three orders of magnitude improvement from conventional direct current sensing approaches as the traditionally dominant interflake interactions are bypassed in favor of selectively extracting intraflake doping effects. This same approach allows for an all solution-processed, flexible 2D sensor to be fabricated on a polyimide substrate using a combination of graphene contacts and drop-casted MoS2 nanoflakes, exhibiting similar sensitivity limits. Finally, a thermal annealing strategy is used to explore the tunability of the nanoflake interactions and subsequent circuit model fit, with a demonstrated sensitivity improvement of 2× with thermal annealing at 200 °C.

Original languageEnglish (US)
Article number2106830
JournalAdvanced Functional Materials
Issue number12
StatePublished - Mar 16 2022


  • 2D materials
  • impedance spectroscopy
  • liquid phase exfoliation
  • molybdenum disulfide
  • sensors

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics


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