Advanced functional polymer membranes

The analysis of various parameters of metal oxides and the search of criteria, which could be used during material selection for solid-state gas sensor applications, were the main objectives of this review. For these purposes the correlation between electro-physical (band gap, electroconductivity, type of conductivity, oxygen diffusion), thermodynamic, surface, electronic, structural properties, catalytic activity and gas-sensing characteristics of metal oxides designed for solid-state sensors was established. It has been discussed the role of metal oxide manufacturability, chemical activity, and parameter's stability in sensing material choice as well.

Metal oxides for solid-state gas sensors: What determines our choice?

This article gives an overview of the application of nanomaterials in environmental remediation. In the area of environmental remediation, nanomaterials offer the potential for the efficient removal of pollutants and biological contaminants. Nanomaterials in various shapes/morphologies, such as nanoparticles, tubes, wires, fibres etc., function as adsorbents and catalysts and their composites with polymers are used for the detection and removal of gases (SO2, CO, NOx, etc.), contaminated chemicals (arsenic, iron, manganese, nitrate, heavy metals, etc.), organic pollutants (aliphatic and aromatic hydrocarbons) and biological substances, such as viruses, bacteria, parasites and antibiotics. Nanomaterials show a better performance in environmental remediation than other conventional techniques because of their high surface area (surface-to-volume ratio) and their associated high reactivity. Recent advances in the fabrication of novel nanoscale materials and processes for the treatment of drinking water and industrial waste water contaminated by toxic metal ions, radionuclides, organic and inorganic solutes, bacteria and viruses and the treatment of air are highlighted. In addition, recent advances in the application of polymer nanocomposite materials for the treatment of contaminants and the monitoring of pollutants are also discussed. Furthermore, the research trends and future prospects are briefly discussed.

A review on nanomaterials for environmental remediation

Laboratoire de Génie Enzymatique et Biomoléculaire, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, 43 Boulevard du 11 Novembre 1918, Villeurbanne F-69622, France, UMR5246, Centre National de La Recherche Scientifque, Villeurbanne F-69622, France, Université de Lyon, Lyon F-69622, France, Université Lyon 1, Lyon F-69622, France, Institut National des Sciences Appliquées de Lyon, EÄ cole d’Ingénieurs, Villeurbanne F-69621, France, and EÄ cole Supérieure Chimie Physique EÄ lectronique de Lyon, Villeurbanne F-69616, France

DNA biosensors and microarrays.

There is an enormous demand for chemical sensors for many areas and disciplines. High sensitivity and ease of operation are two main issues for sensor development. Fluorescence techniques can easily fulfill these requirements and therefore fluorescent-based sensors appear as one of the most promising candidates for chemical sensing. However, the development of sensors is not trivial; material science, molecular recognition and device implementation are some of the aspects that play a role in the design of sensors. The development of fluorescent sensing materials is increasingly captivating the attention of the scientists because its implementation as a truly sensory system is straightforward. This critical review shows the use of polymers, sol–gels, mesoporous materials, surfactant aggregates, quantum dots, and glass or gold surfaces, combined with different chemical approaches for the development of fluorescent sensing materials. Representative examples have been selected and they are commented here.

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Design of fluorescent materials for chemical sensing

Polymers in sensor applications

There are reports of taste sensor fabrication by incorporating lipids in a PVC matrix. We have taken an attempt to prepare a taste sensor material by using a functionalized polymer. Polyvinyl alcohol (PVA) has been modified to fabricate the sensor material. The research work covers polymer membrane preparation, morphology study, structural characterization of the membrane, and study of the taste sensing characteristics. The membrane was prepared by cross-linking polyvinyl alcohol with maleic acid. The cross-linked PVA was phosphorylated with POCl 3 . Polyvinyl alcohol membranes of suitable thickness were thus prepared with a good threshold sensing value and less swelling in water. FTIR spectroscopic analysis, XRD analysis and optical microscopy were done to get an idea about the structure and morphology of the polymer membranes. The sensor characteristics like temporal stability, response stability, response to different taste substances, and reproducibility of sensing performance were studied. The threshold concentrations of the membrane for Q-HCl, HCl, MSG, NaCl and sucrose were 0.01, 0.001, 0.08, 1, and 1 mM, respectively. These membrane threshold concentrations are below human threshold concentrations, which are 0.03, 0.9, 1.6, 30 and 170 mM for Q-HCl, HCl, MSG, NaCl and sucrose, respectively.

Polyvinyl alcohol : A taste sensing material

Taste sensing with polyacrylic acid grafted cellulose membrane.

There are reports of fabrication of taste sensor by adsorbing lipids into Millipore filter paper. With this lipid based sensor, it has been found that the taste sensing efficiency of membrane can be remarkably improved. We have made an attempt to prepare taste sensor material by using functionalized polymer without any lipid. PVA-cellulose composite has been modified to use as the sensor material. The research work covers polymer membrane preparation, morphology study and structural characterization of the membrane and study of the taste sensing characteristics of this membrane for five different taste substances. PVA-cellulose composite membrane was modified by phosphorylation with POCl3. FTIR spectroscopic analysis, XRD analysis and SEM were done to get an idea about the structure and morphology of the prepared phosphorylated PVA-cellulose composite membrane. The sensor characteristics like temporal stability, response stability, response to different taste substances, and reproducibility of sensing performance were studied using phosphorylated PVA-cellulose composite membrane. Sensor device prepared with this membrane has shown distinct response patterns for different taste substances in terms of membrane potential. Threshold concentrations of phosphorylated PVA-cellulose composite membrane for HCl, NaCl, Q-HCl, sucrose and MSG are 0001 mM, 0.001 mM, 0.001 mM, 0.001 mM and 0.009 mM, respectively. The threshold concentrations are below human threshold concentrations. Membranes also showed characteristic response patterns for organic acids like acetic acid, citric acid, formic acid etc, mineral acids like HCl, H2SO4 and HNO3 salts, bitter substances, sweet substances and umami substances. Sensor device prepared with this membrane has excellent shelf life.

/pdf/polyvinyl-alcohol-cellulose-composite-a-taste-sensing-4mj3iur11n.pdf

Sarmishtha Majumdar

Papers

Polymers in sensor applications

Polyvinyl alcohol : A taste sensing material

Taste sensing with polyacrylic acid grafted cellulose membrane.

Polyvinyl alcohol-cellulose composite: a taste sensing material

Taste sensing with cellophane phosphate membrane