Characterization of a Wake-Up Nano-Gap Gas Sensor for Ultra Low Power Operation

• Published in: Journal of microelectromechanical systems Vol. 31; no. 5; pp. 791 - 801
• Main Authors: Khan, Shakir-ul Haque, Banerjee, Aishwaryadev, Broadbent, Samuel, Noh, Seungbeom, Kim, Kyeong Heon, Bulbul, Ashrafuzzaman, Looper, Ryan E., Mastrangelo, Carlos H., Kim, Hanseup
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Chemical sensors; Chemistry; Coatings; Electrodes; Gas detectors; gas sensor; Gas sensors; Gold; Matching; molecular bridging; nano-gap; Power consumption; Sensors; ultra-low-power; Wake-up
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2022.3189926

This paper reports the performance characterization of a wake-up nano-gap gas sensor with ultra-high-sensitivity due to its dependence on the electron tunneling distance that was experimentally modulated by a structural nano-gap, a chemistry linker length and a molecular size of target gases. The wake-up sensor became activated when the nano-gap was bridged for electron flow by the capture of specific target gas molecules. The fabricated nano-gap sensor demonstrated highly sensitive and selective responses to the dimensional variations in the gaps, the linkers and the target VOCs: (1) only 5-Å difference in either the nano-gap distance or the linker length produced the output signal ratios of two to five orders in magnitudes, indicating ultra-highly-sensitive characteristics; (2) only two carbon length difference of 2.3-Å between target gases with the identical functional group resulted in the output signal ratios of up to four orders in magnitudes, implying the unique distinguish capability of molecular-level length differences, and (3) the selectivity against 7 major interference gas groups in high concentrations (>1,000 ppm) was measured as at least by four orders in magnitude indicating the benefits of size-matching in gas detection on top of conventional chemistry-matching. The fabricated nano-gap gas sensor ultimately showed ultra-low power consumption of 20.08 pW during the sleep mode and repeatability of >10 cycles. These results indicated that the nano-gap sensor can be <inline-formula> <tex-math notation="LaTeX">a </tex-math></inline-formula> highly sensitive and selective alternative in gas sensing especially in resource-limited environments. [2022-0039]