Nanocomposite based flexible ultrasensitive resistive gas sensor for chemical reactions studies

Abstract

Room temperature operation, low detection limit and fast response time are highly desirable for a wide range of gas sensing applications. However, the available gas sensors suffer mainly from high temperature operation or external stimulation for response/recovery. Here, we report an ultrasensitive-flexiblesilver-nanoparticle based nanocomposite resistive sensor for ammonia detection and established the sensing mechanism. We show that the nanocomposite can detect ammonia as low as 500 parts-per-trillion at room temperature in a minute time. Furthermore, the evolution of ammonia from different chemical reactions has been demonstrated using the nanocomposite sensor as an example. Our results demonstrate the proof-of-concept for the new detector to be used in several applications including homeland security, environmental pollution and leak detection in research laboratories and many others.A mmonium nitrate is present in many explosives and is known to gradually decompose and release trace amounts of ammonia. It is, therefore, essential to detect a trace of the gas to prevent the fatal accidents. The variation of conductivity of metal oxides and conducting polymers has been explored for the detection of ammonia in ppb (parts-per-billion) range. The conventional solid state and conducting polymer sensors suffer from ultralow detection at room temperature . The commercially available conducting polymer sensors require high power consumption since they provide adequate sensitivity only at high temperatures. Intense research is underway to develop new sensing materials and devices for a wide range of applications, especially, at room temperature. It has been shown that the graphene and carbon nanotube based detectors can operate at room temperature [27][28][29][30][31][32] . However, it is required to supply air or oxygen along with ammonia and apply either a current of 100 mA or UV illumination in order to clean the adsorbed gas molecules for sensor recovery [27][28][29][30][31][32] . A self-activated highly sensitive graphene 32 or metal oxide nanostructures 33 have been reported where the response time is few minutes.An ideal sensor should possess the following significant features: (i) operation at room temperature; (ii) working in ambient environment and no requirement of oxygen or air supply; (iii) no external stimulus such as Joule heating or UV illumination for response/recovery; (iv) low detection limit; (v) high sensitivity and reproducibility; (vi) fast response and recovery; (vii) low cost and eco-friendly, etc. We have previously reported the aqueous ammonia sensing of guar gum/silver nanoparticles (GG/Ag) solutions based on the variation of the surface plasmon resonance (SPR) peaks 34 . Limitations of the method are that the solution cannot be reused and the detection limit is ppm level. Here, we report an ultrasensitive chemiresistor sensor based on GG/Ag nanocomposite for ammonia detection. The conductance of the sensor increases and the change is shown to be improved by increasing the loading of Ag n...

Sniffing Bacteria with a Carbon-Dot Artificial Nose

“…2 b-i reveals two linear regions, one between 0 and 50 ppmv and another linearity between 50 and 100 ppmv. The two linear capacitive response domains likely correspond to different mechanisms of ammonia adsorption onto the C-dot-IDE surface; indeed, distinct NH 3 concentration-dependent surface-adsorption regimes have been reported, indicating NH 3 monolayer formation in low concentrations, multilayer assembly in higher ammonia concentrations [ 34 – 36 ]. In the case of exposure of the red C-dot-IDE sensor to DMF, a single linear dependence was apparent (Fig.…”

Ammonia gas sensors based on chemically reduced graphene oxide sheets self-assembled on Au electrodes

“…Chemiresistive sensors have aroused much attention in environment monitoring, industry and agriculture production, medical diagnosis, military, and public safety, etc. nowadays [ 1 - 5 ]. In order to meet the requirements of industry and other fields' demands, semi-conducting metal oxide, organic semiconductors, and carbon materials, etc., which have high aspect ratio and large specific surface area, have been widely used as sensing materials and the excellent performances of the resultant devices have been achieved [ 6 - 8 ].…”

Recent Advances in Ammonia Gas Sensors Based on Carbon Nanomaterials

“…Pandey et al [ 109 ] mentioned the typical features that a gas sensor should possess: (i) operation at room temperature; (ii) working in ambient environment and no requirement of oxygen or air supply; (iii) no external stimulus such as Joule heating or UV illumination for response/recovery; (iv) low detection limit; (v) high sensitivity and reproducibility; (vi) fast response and recovery; (vii) low cost and eco-friendly, etc. This list is extended enough, but some points may be added.…”

“…The range of the concentrations of ammonia to be detected ranges from a few ppb to hundreds of ppm. However, some of the authors already reported the sensors are capable of detecting a few ppt (parts per trillion), e.g., guar gum/Ag nanocomposite film [ 109 ]. The sensors based on carbon nanomaterials approach this level.…”