A gold nano-urchin-decorated quasi-freestanding graphene-based humidity sensor with enhanced responsivity and a wide relative humidity detection range for real-time applications

Ishwor Bahadur Khadka, Sheik Abdur Rahman, Jeong Sik Jo, Do Wan Kim, Madhav Prasad Ghimire, Bakhtiar Ul Haq, Woo Young Kim, Se Hun Kim, Jae Won Jang

Research output: Contribution to journalArticlepeer-review

Abstract

Excellent humidity response and detection threshold are essential attributes of a humidity sensor. In this study, quasi-freestanding graphene (QFSG) was grown epitaxially on vicinal silicon carbide via thermal annealing, followed by decoration with hydrophilic gold nano-urchins (AuNUs). The resulting humidity sensor consistently achieved highly effective non-contact humidity-sensing performance, which can be used to monitor breathing and skin moisture. The proposed humidity sensor demonstrated a non-linear response of ∼119.98 % over a wide relative humidity detection range of 4–96 % at a frequency of 1 kHz, outperforming a QFSG-only humidity-sensing device (∼11.92 % and 22–84 % relative humidity, respectively). This 10-fold increase in humidity response and wider detection range is attributed to the hydrophilicity and plasmonic behavior of the AuNUs. It also demonstrated transient impedance response/recovery time of 4.5 and 3.0 s, respectively; low hysteresis of 3.6 %; and stability over 25 days, which are key factors for effective humidity sensing. The fast response and sensitivity of the AuNUs/QFSG humidity sensor made it possible to test for various real-time monitoring applications such as human breathing and non-contact proximity testing.

Original languageEnglish
Article number136739
JournalSensors and Actuators B: Chemical
Volume423
DOIs
StatePublished - 15 Jan 2025

Keywords

  • Gold Nano-urchin
  • Humidity sensor
  • QFSG
  • Responsivity
  • Vicinal SiC
  • Wide-range

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