Potassium Iodide-Functionalized Polyaniline Nanothin Film Chemiresistor for Ultrasensitive Ozone Gas Sensing.

Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of a one-dimensional nanostructure, such as PANI nanowires. In this work, we report further progress in the application of the PANI nanothin film chemiresistive sensor for the detection of ozone (O₃) by modifying the film with potassium iodide (KI). The KI-PANI sensor exhibited an excellent sensitivity to O₃ (8⁻180 ppb O₃ concentration rage) with a limit of detection of 230 ppt O₃, and exquisite selectivity against active chemicals such as nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). The sensing mechanism of the sensor relied on iodometric chemistry of KI and O₃, producing triiodide ( I 3 - ) that partially doped and increased electrical conductivity of the PANI film. The sensitivity and selectivity of the KI-functionalized PANI film demonstrates the potential use for KI-PANI-based O₃ sensing devices in environmental monitoring and occupational safety

Polyaniline Nanothin Film Chemiresistive Gas Sensors

Conducting polymers (CPs) are a group of conjugated polymers offering unique electrical/electronic properties of metals/semiconductors while retaining the attractive mechanical properties and processing advantages of polymers. In particular, polyaniline (PANI), because of its stability in ambient conditions and wide range of tunable electrical conductivity, is one of the most prominent CPs receiving a great deal of attention. The conductivity of PANI can be varied from insulating to nearly metallic by modulating its oxidative state by changing the type of counter ion (dopant) and degree of doping. The ability to switch between the conducting and insulating forms makes PANI responsive to acid/base and reducing/oxidizing compounds, enabling it to be used as sensing element in resistance type sensors known as chemiresistors.In this dissertation, we demonstrated a novel method for electrochemical growth of conducting polymer polyaniline (PANI) nanothin film across a pair of gold microelectrodes on Si/SiO2 for one step and site-specific fabrication of PANI film based field-effect transistor/chemiresistor sensors. Various instrumentation techniques, including scanning electron microscope (SEM), atomic force microscopy (AFM), field-effect transistors (FET), and X-ray photoelectron spectroscopy (XPS) were applied to acquire physical and electrical properties of the nanothin film.The film had a thickness of 9-20 nm and a carpet-like morphology offering high surface to volume ratio that enhances gas adsorption and promotes surface perturbation. The sensing performance of the nanothin film device was comparable to that of 1-dimensional (1-D) nanostructure, with a great advantage in ease of processing and durability in post-synthesis functionalization. The film was further functionalized using a dip coating process to introduce recognition material into the polymer domain for enhancing reactivity and selectivity of the film transducer. The nanothin film was functionalized with primary amine, polyethyleneimine, potassium iodide and cupric chloride for highly sensitive and selective detection of formaldehyde, carbon dioxide, ozone and nerve agent sarin simulant dimethyl methylphosphonate, respectively

ZnS nanocrystals decorated single-walled carbon nanotube based chemiresistive label-free DNA sensor

We fabricated ZnS nanocrystals decorated single-walled carbon nanotube (SWNT) based chemiresistive sensor for DNA. Since the charge transfer in the hybrid nanostructures is considered to be responsible for many of their unique properties, the role of ZnS nanocrystals toward its performance in DNA sensor was delineated. It was found that the free carboxyl groups surrounding the ZnS nanocrystals allowed large loading of single strand DNA (ssDNA) probe that provided an ease of hybridization with target complementary c-ssDNA resulting in large electron transfer to SWNT. Thus it provided a significant improvement in sensitivity toward c-ssDNA as compared to bare SWNT based DNA sensor

Potassium Iodide-Functionalized Polyaniline Nanothin Film Chemiresistor for Ultrasensitive Ozone Gas Sensing.

Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of a one-dimensional nanostructure, such as PANI nanowires. In this work, we report further progress in the application of the PANI nanothin film chemiresistive sensor for the detection of ozone (O₃) by modifying the film with potassium iodide (KI). The KI-PANI sensor exhibited an excellent sensitivity to O₃ (8⁻180 ppb O₃ concentration rage) with a limit of detection of 230 ppt O₃, and exquisite selectivity against active chemicals such as nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). The sensing mechanism of the sensor relied on iodometric chemistry of KI and O₃, producing triiodide ( I 3 - ) that partially doped and increased electrical conductivity of the PANI film. The sensitivity and selectivity of the KI-functionalized PANI film demonstrates the potential use for KI-PANI-based O₃ sensing devices in environmental monitoring and occupational safety

Potassium Iodide-Functionalized Polyaniline Nanothin Film Chemiresistor for Ultrasensitive Ozone Gas Sensing

Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of a one-dimensional nanostructure, such as PANI nanowires. In this work, we report further progress in the application of the PANI nanothin film chemiresistive sensor for the detection of ozone (O3) by modifying the film with potassium iodide (KI). The KI-PANI sensor exhibited an excellent sensitivity to O3 (8–180 ppb O3 concentration rage) with a limit of detection of 230 ppt O3, and exquisite selectivity against active chemicals such as nitrogen dioxide (NO2) and sulfur dioxide (SO2). The sensing mechanism of the sensor relied on iodometric chemistry of KI and O3, producing triiodide ( I 3 − ) that partially doped and increased electrical conductivity of the PANI film. The sensitivity and selectivity of the KI-functionalized PANI film demonstrates the potential use for KI-PANI-based O3 sensing devices in environmental monitoring and occupational safety