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Conductive polymers in the form of pellet and coating on a suitable substrate have been extensively used in recent years as sensor materials for the vapor phase sensing of aliphatic alcohols. But due to lack of mechanical stability and reversible adsorption/desorption of alcohol molecules the use of conducting polymers in the above forms suffers fr...
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... composite membrane was measured at ambient temperature (30 C) by four-probe method using a Keithley 2400 source meter. Copper wire was used for the preparation of the probes. Conducting silver paste was used as adhesive to make a contact between copper wire and polymer film/membrane. A four point collinear method [23] was employed as shown in Fig. 1. The four probe contacts (labelled 1-4) were made on the surface of the sample in a linear array. A current (I) was passed through the outer contacts (1 and 4) and the voltage (V) was measured using probes 2 and 3. The conductivity was calculated by the equation ...Context 2
... sensing responses of CSA- PANI-PVA polymer membrane sensor to methanol, ethanol, propanol and isopropanol vapors at different concentrations, viz., 1, 25, 50, 100 and 200 ppm, are shown in Fig. 8. For PTSA-PANI- PVA membrane sensor, sensing responses of alcohol vapors are shown in Fig. 9 and those of ASP-PANI-PVA membrane sensor are shown in Fig. 10. The membrane sensor exhibited spontaneous decrease in electrical resistance (R/R 0 ) upon exposure to aliphatic alcohol, followed by subsequent recovery to initial resistance after being exposed to air. The functional sites, viz., sulphonic acid, carboxylic acid, amine and hydroxyl functional groups present within the dopants and PVA, ...Context 3
... different for different alcohol vapors. These differences in responses could be used as a basis for the selective determina- tion of these alcohol vapors. In order to better resolve the selectivity characteristics of the polymer membrane sensor, the sensing responses of aliphatic alcohols have been plotted against their concentrations in Fig. 11 for CSA-PANI-PVA membrane. For other two polymer membranes, these plots are shown in Supplementary section (Figs. S1 and S2). For all the aliphatic alcohol vapors, the polymer membrane sensor exhibits a good relative linear response with increasing vapor concentration, having different correlation coefficient (R 2 ) values for ...Context 4
... ethanol, propanol and isopropanol are 0.9607, 0.9571, 0.9489 and 0.9778, respectively, indicating better linear correla- tionship for the methanol, ethanol and isopropanol sensing compared to propanol. The slope of the curve indicates the sensor responsivity (responsivity = response of the sensor/alcohol vapor concentration). It is observed from Fig. 11 that higher responsivity is achieved for methanol vapor sensing with the value of 0.1744% per ppm, followed by ethanol, isopropanol and propanol sensing as 0.1423%, 0.1113% and 0.0923% per ppm, respectively. Hence, each Table 4 Response characteristics of CSA-PANI-PVA, PTSA-PANI-PVA and ASP-PANI-PVA membrane sensors towards different ...Context 5
... towards methanol, ethanol, propanol and isopropanol vapors. Some residual adsorbed aliphatic alcohol molecules at the sensor surface after 1st cycle might be the reason for slight lower response time of consecutive 2nd and 3rd cycle than that of 1st one for all the concentrations of methanol, ethanol, propanol and isopropanol in air as seen in Figs. ...Similar publications
Electrodeposition on substrates or monolayers is problematic as there are several factors influencing the process such as growth rate, temperature, humidity, substrate surface cleanliness, solubility, agglomeration and stability of the materials. These factors do not only inhibit the electrodeposition process but also present challenges to research...
Citations
... The sensor response was associated with the changes in refractive index of the solution depending on the chain length of the alcohols. Aliphatic alcohol vapor sensing characteristics were evaluated using doped polyvinyl alcohol (PVA)-PANI membrane [214]. PVA-PANI membranes were doped with various dopants, namely, CSA, p-TSA and L-ascorbic acid. ...
The electronic conjugation between each repeat unit in conducting polymers (CPs) provides semiconducting molecular architectures and intriguing properties to suit for sensing applications. Therefore, considerable progress has been demonstrated on sensor designs with CPs. Unfortunately, the most essential requirements of sensors such as selectivity of an analyte and detection of a specific analyte in a complex environment are hard to achieve with pristine CPs. These constraints in pristine CPs along with processability limitations necessitate the development of functionalized CPs (FCPs) through intelligent structural modification of pristine CPs or inclusion of a functional property modifying components with CPs. On perusal of the literature in last 10-15 years on the use of FCPs for sensor application reveal that FCPs can out-perform basic function at the molecular levels, such as recognition and control of chemical processes, as well as inform that the unique physical, chemical and electrochemical properties of FCPs could be effectively exploited to improve the selectivity, sensitivity, and throughput of sensors beyond the limits of existing detection techniques. Herein, we provide the first review of FCP materials utilized for sensor fabrications highlighting, in particular, the advances in the synthesis of FCPs employing strategies for the inclusion of functional group/functional component(s) to suit for sensing the specific analyte(s), the improvements in sensor performances (detection limit and linear range) and the role of FCPs in the sensing process. The in-depth analysis of the literature on the use of FCPs for sensors suggests that these research activities are rapidly maturing at the convergence of nanotechnology and biotechnology. We arrange the great number of FCPs utilized for sensing element into four categories; substituted or derivatized FCPs (category I), biofunctionalized FCPs (category II), nanostructured FCPs (category III) and multicomponent FCPs (category IV). This review highlights prominent examples of FCPs as applicable to main type of CPs such as polypyrrole, polyaniline, polythiophene, polyfluorene and other CPs. We also identify how certain functionalization improves sensor performances. In addition, this review presents a discussion of state of the art of FCPs used in the preparation of molecular imprinted polymers (MIPs) intended for molecular recognition/sensor applications. In the final stage, we summarize the characteristics of FCPs with relevance to MIP and sensor designs and propose several prospectives for using FCP as a new sensing platform for the development of next-generation sensors.
Conducting polymer (CP) hybrids, which combine CPs with heterogeneous species, have shown strong potential as electrical transducers in chemosensors. The charge transport properties of CPs are based on chemical redox reactions and provide various chemo-electrical signal transduction mechanisms. Combining CPs with other functional materials has provided opportunities to tailor their major morphological and physicochemical properties, often resulting in enhanced sensing performance. The hybrids can provide an enlarged effective surface area for enhanced interaction and chemical specificity to target analytes via a new signal transduction mechanism. Here, we review a selection of important CPs, including polyaniline, polypyrrole, polythiophene and their derivatives, to fabricate versatile organic and inorganic hybrid materials and their chemo-electrical sensing performance. We focus on what benefits can be achieved through material hybridization in the sensing application. Moreover, state-of-the-art trends in technologies of CP hybrid sensors are discussed, as are limitations and challenges.
