A Highly Sensitive and Stable rGO:MoS2‑Based Chemiresistive Humidity Sensor Directly Insertable to Transformer Insulating Oil Analyzed by Customized Electronic Sensor Interface

• Published in: ACS sensors Vol. 6; no. 3; pp. 1012 - 1021
• Main Authors: Adib, Md Ridwan, Lee, Yongbum, Kondalkar, Vijay V, Kim, Sihyeok, Lee, Keekeun
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26-03-2021
• Subjects: molybdenum disulfide; humidity sensor; reduced graphene oxide; in-plane microheater; transformer insulating oil; temperature sensor
• ISSN: 2379-3694; 2379-3694
• DOI: 10.1021/acssensors.0c02219

Reduced graphene oxide and molybdenum disulfide (rGO:MoS2) are the most representative two-dimensional materials, which are promising for a humidity sensor owing to its high surface area, a large number of active sites, and excellent mechanical flexibility. Herein, we introduced a highly sensitive and stable rGO:MoS2-based humidity sensor integrated with a low-power in-plane microheater and a temperature sensor, directly insertable to transformer insulating oil, and analyzed by a newly developed customized sensor interface electronics to monitor the sensor’s output variations in terms of relative humidity (RH) concentration. rGO:MoS2 sensing materials were synthesized by simple ultrasonication without using any additives or additional heating and selectively deposited on titanium/platinum (Ti/Pt) interdigitated electrodes on a SiO2 substrate using the drop-casting method. The significant sensing capability of p–n heterojunction formation between rGO and MoS2 was observed both in the air and transformer insulating oil environment. In air testing, the sensor exhibited an immense sensitivity of 0.973 kΩ/%RH and excellent linearity of ∼0.98 with a change of humidity from 30 to 73 %RH, and a constant resistance deviation with an inaccuracy rate of 0.13% over 400 h of continual measurements. In oil, the sensor showed a high sensitivity of 1.596 kΩ/%RH and stable repeatability for an RH concentration range between 34 and 63 %RH. The obtained results via the sensor interface were very similar to those measured with a digital multimeter, denoting that our developed total sensor system is a very promising candidate for real-time monitoring of the operational status of power transformers.