Ionic‐Activated Chemiresistive Gas Sensors for Room‐Temperature Operation

Abstract

extensively studied because of their remarkable advantages including low cost, simple fabrication, high response, and easy integration with electronic circuits. To ensure high response and reversible operation of chemiresistive gas sensors, high operating temperatures of 150-400 °C are inevitably required for adsorption and desorption of target molecules on and off of the sensing materials. [3,4] However, this high temperature degrades the sensor stability and lifetime due to thermally induced grain growth, which can damage interconnected electronics. [5,6] Moreover, high power consumption (over ≈100 mW) is required, which must be decreased for the development of future battery-powered wireless sensors for applications to the IoT. [7] To design high performance gas sensors that operate at room temperature, a variety of approaches including self-heating, ultraviolet (UV)-assisted measurements, and 2D materials have been used for high stability and low power consumption. [8][9][10] Despite these extensive efforts, challenges remain including poor response and incomplete recovery because of the restricted modulation in electronic conductivity by insufficient reaction energy between the analytes and sensing materials. Recently, the utilization of humidity has been reported as an effective method for improving gas sensing performance at low temperatures.The development of high performance gas sensors that operate at room temperature has attracted considerable attention. Unfortunately, the conventional mechanism of chemiresistive sensors is restricted at room temperature by insufficient reaction energy with target molecules. Herein, novel strategy for room temperature gas sensors is reported using an ionic-activated sensing mechanism. The investigation reveals that a hydroxide layer is developed by the applied voltages on the SnO 2 surface in the presence of humidity, leading to increased electrical conductivity. Surprisingly, the experimental results indicate ideal sensing behavior at room temperature for NO 2 detection with sub-parts-per-trillion (132.3 ppt) detection and fast recovery (25.7 s) to 5 ppm NO 2 under humid conditions. The ionic-activated sensing mechanism is proposed as a cascade process involving the formation of ionic conduction, reaction with a target gas, and demonstrates the novelty of the approach. It is believed that the results presented will open new pathways as a promising method for room temperature gas sensors. Sensors/BiosensorsThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Cross-linked structure of self-aligned p-type SnS nanoplates for highly sensitive NO2 detection at room temperature

“…SiO 2 nanorods with approximate heights and diameters of 300 nm and 30 nm, respectively, were formed on the pre-patterned area between the Au electrodes by a glancing angle deposition technique. 34–36 Subsequently, ALD SnS nanoplates were formed by ALD of SnS. The SnS nanoplates were selectively grown on SiO 2 nanorods, even without a specific patterning process.…”

“…The detailed procedure for the fabrication of the nanorods has been previously reported. 34–36 SnS was deposited in a travelling wave-type chamber by ALD from Sn(dmamp) 2 and H 2 S. ALD was performed at 240 °C under a nominal working pressure of 1 Torr. The ALD cycle consisted of Sn precursor feeding for 2 s, purging for 10 s, S precursor feeding for 2 s, and purging for 20 s. The details of the ALD process for SnS can be found in our previous reports.…”

Metal Oxide Nanorods-Based Sensor Array for Selective Detection of Biomarker Gases

“…To overcome these drawbacks, many researchers have studied metal oxide semiconductors (MOSs) due to their outstanding advantages, such as low cost, simplicity in fabrication, high sensitivity, easy integration with electronic circuits, and a large number of detectable gases [ 14 ]. Cutting-edge research has been spotlighted to apply the nanostructured materials [ 15 ], catalysts [ 16 ], heterojunctions [ 17 ], and UV activation [ 18 ] to the sensors for the enhancement of gas sensing performance.…”

Metastable Antimony‐Doped SnO2 Quantum Wires for Ultrasensitive Gas Sensors

“…Metal oxide semiconductor (MOS) based gas sensors, typically n‐type SnO 2 chemiresistors, are featured by their superb sensitivity, easy operation as well as low cost. [ 1,2 ] The increasing demand for ubiquitous and reliable gas detection is spurring the design of novel MOS materials that exhibit engineered chemical and electronic properties and that can enable new fabrication methods for low‐power‐consumption gas sensors. [ 3,4 ] Colloidal semiconductor nanocrystals (such as SnO 2 , [ 5 ] WO 3 , [ 6 ] ZnO, [ 7 ] and In 2 O 3 [ 8 ] ) offer an abundance of available surface area for chemical and electronic interactions, making them ideal receptors for gas molecules.…”