Rational Design of Sub-Parts per Million Specific Gas Sensors Array Based on Metal Nanoparticles Decorated Nanowire Enhancement-Mode Transistors

Abstract

"One key to one lock" hybrid sensor configuration is rationally designed and demonstrated as a direct effective route for the target-gas-specific, highly sensitive, and promptly responsive chemical gas sensing for room temperature operation in a complex ambient background. The design concept is based on three criteria: (i) quasi-one-dimensional metal oxide nanostructures as the sensing platform which exhibits good electron mobility and chemical and thermal stability; (ii) deep enhancement-mode field-effect transistors (E-mode FETs) with appropriate threshold voltages to suppress the nonspecific sensitivity to all gases (decouple the selectivity and sensitivity away from nanowires); (iii) metal nanoparticle decoration onto the nanostructure surface to introduce the gas specific selectivity and sensitivity to the sensing platform. In this work, using Mg-doped In2O3 nanowire E-mode FET sensor arrays decorated with various discrete metal nanoparticles (i.e., Au, Ag, and Pt) as illustrative prototypes here further confirms the feasibility of this design. Particularly, the Au decorated sensor arrays exhibit more than 3 orders of magnitude response to the exposure of 100 ppm CO among a mixture of gases at room temperature. The corresponding response time and detection limit are as low as ∼4 s and ∼500 ppb, respectively. All of these could have important implications for this "one key to one lock" hybrid sensor configuration which potentially open up a rational avenue to the design of advanced-generation chemical sensors with unprecedented selectivity and sensitivity.

Recent Progress on the Development of Chemosensors for Gases

“…In this case, E-mode Mg-doped In 2 O 3 nanowire FET arrays were employed as the gas sensing platform and decorated with Au, Ag, and Pt nanoparticles to provide specific selectivity for reducing gases such as CO, C 2 H 5 OH, and H 2 . 177 Figure 58 illustrates an example of a "one lock to one key" sensor system. On the other hand, the metal nanowire channel in the deep Emode FETs decorated with nanoparticles could exhibit unique single-target gas-specific responses.…”

One-Dimensional Nanostructure Field-Effect Sensors for Gas Detection

“…Ho et al used Mg-doped In 2 O 3 nanowire enhanced-mode field-effect sensor arrays decorated with various discrete metal nanoparticles ( i.e. , Au, Ag and Pt), to selectively distinguish among three reducing gases (e.g., CO, C 2 H 5 OH and H 2 ), with high sensitivity [8]. The deep enhanced-mode FET could not detect the reducing or oxidizing gases, which provided an ideal platform to introduce the gas selectivity and sensitivity into the nanowire surface by decorating various metal nanoparticles.…”

“…The surface of nanowires was decorated with Au, Ag, and Pt nanoparticles, respectively; ( b ) Optical (top left) and SEM (right) image of the chemical sensor arrays. High magnification SEM (bottom left) image of Au decorated Mg-doped In 2 O 3 nanowire; ( c ) The transfer curves for the sensors with and without the metal decoration; ( d – f ) The output curves for Au, Ag and Pt decorated enhanced-mode FETs toward the gas specific detection of O 2 , H 2 , C 2 H 5 OH, and CO [8]. …”

Gas sensing capabilities of TiO2 porous nanoceramics prepared through premature sintering

“…Nanomaterials have been extensively investigated for developing new gas sensors with high sensitivities and low working temperatures in the past decades. Various MOS nanostructures, including nanotubes [3,4], nanowires [5,6], and nanobelts [7], have been synthesized and explored for preparing such gas sensors. Although their sensitivities have been dramatically increased and their working temperatures have been considerably lowered even down to room temperature, all those sensors have not been commercialized for practical applications up to date due to some shortcomings inherent in low dimensional MOSs, such as low thermal stability and mechanical strength [8,9], strong adsorption of moisture [10], and difficulty in mass production.…”