TY - JOUR
T1 - Sensing performance of Nanocrystalline Graphite Based Humidity Sensors
AU - Ling, Ting Yang
AU - Pu, Suan Hui
AU - Fishlock, Sam
AU - Han, Yisong
AU - Reynolds, Jamie
AU - McBride, John
AU - Chong, Harold
PY - 2019/7/15
Y1 - 2019/7/15
N2 - Environmental sensors play a crucial role in a wide range of applications. Among them, humidity sensors that are stable and operational in harsh environments are incredibly important for process control and monitoring. Nanocrystalline graphite (NCG) is a type of carbon-based thin film material. Previous work has shown that NCG has excellent mechanical properties and is able to withstand high radiation doses. The granular structure of the NCG film makes it a good candidate for humidity sensing as the film consists of conductive graphitic grains with a high density of sp 2 bonds and amorphous grain boundaries with high resistivity, and adsorption of water molecule onto the film forms conductive pathways between grains through the Grotthuss mechanism which lowers the resistance of the film by a measurable amount. Here, we report for the first time a working humidity sensor with linear response, fabricated using NCG as the sensing material for harsh, real-world environments, which include exposure to weak acids via rainfall, UV radiation, mechanical wear, and high-humidity environments. The calculated sensitivity of the best-fabricated sensor is S = 0.0334 %, with a maximum resistance change of -4.4kΩ , over the range of 15% RH to 85% RH. The response time of the sensor is 20 ms with the current measurement setup. The baseline resistance value of the sensor at 15% RH is 210 kΩ. The sensor has the potential to be used as a humidity sensor for harsh environments due to the chemical, thermal, and mechanical stability of the NCG film.
AB - Environmental sensors play a crucial role in a wide range of applications. Among them, humidity sensors that are stable and operational in harsh environments are incredibly important for process control and monitoring. Nanocrystalline graphite (NCG) is a type of carbon-based thin film material. Previous work has shown that NCG has excellent mechanical properties and is able to withstand high radiation doses. The granular structure of the NCG film makes it a good candidate for humidity sensing as the film consists of conductive graphitic grains with a high density of sp 2 bonds and amorphous grain boundaries with high resistivity, and adsorption of water molecule onto the film forms conductive pathways between grains through the Grotthuss mechanism which lowers the resistance of the film by a measurable amount. Here, we report for the first time a working humidity sensor with linear response, fabricated using NCG as the sensing material for harsh, real-world environments, which include exposure to weak acids via rainfall, UV radiation, mechanical wear, and high-humidity environments. The calculated sensitivity of the best-fabricated sensor is S = 0.0334 %, with a maximum resistance change of -4.4kΩ , over the range of 15% RH to 85% RH. The response time of the sensor is 20 ms with the current measurement setup. The baseline resistance value of the sensor at 15% RH is 210 kΩ. The sensor has the potential to be used as a humidity sensor for harsh environments due to the chemical, thermal, and mechanical stability of the NCG film.
KW - Humidity , Mechanical sensors , Graphite , Graphene , Chemical sensors , Resistance
KW - Nanocrystalline graphite
KW - humidity sensors
KW - PECVD
KW - harsh environment
UR - http://www.scopus.com/inward/record.url?scp=85067942219&partnerID=8YFLogxK
UR - https://pure.ulster.ac.uk/en/publications/sensing-performance-of-nanocrystalline-graphite-based-humidity-se
U2 - 10.1109/JSEN.2019.2905719
DO - 10.1109/JSEN.2019.2905719
M3 - Article
VL - 19
SP - 5421
EP - 5428
JO - IEEE Sensors Journal
JF - IEEE Sensors Journal
SN - 1530-437X
IS - 14
M1 - 8668501
ER -