A highly sensitive cantilever type chemo-mechanical hydrogen sensor with a novel sensing mechanism that can detect changes in contact resistance in self-adjusted carbon nanotube (CNT) arrays is described. The fabricated sensor is fully batch-fabricated on a silicon-on-insulator (SOI) wafer and is composed of two facing sets of CNT arrays, situated between a Pd-coated micro-cantilever, that serve as the electrode and counter-electrode. When the sensor is exposed to various concentrations of hydrogen at room temperature, resistance is decreased as the cantilever deforms and increases inter-CNT contact. Turning off the hydrogen re-shrinks the Pd, restoring the original cantilever position and recovering the initial resistance. The sensor can detect hydrogen diluted in nitrogen at concentrations of up to 4% and has an average response as high as -1.22% to a 0.1% concentration of hydrogen in air, which is the minimum detection limit. This sensitivity, which is much higher than in previously reported cantilever-type resistive chemo-mechanical hydrogen sensors, can be attributed to the novel sensing mechanism in which the narrow-gap between CNT arrays comprise the sensing component.
Bibliographical noteFunding Information:
The authors are grateful to Prof. Wooyoung Lee for the measurement apparatus. This research was supported by the Fusion Research Program for Green Technologies (NRF-2010-0019088), the Converging Research Center Program (2013K000388), the Center for Integrated Smart Sensors as Global Frontier Project (CISS-2012M3A6A6054201) and the National Research Foundation of Korea (NRF-2012R1A1A2043661) through the Ministry of Science, ICT and Future Planning and the Ministry of Education, Korea.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry