An Inter-digital Capacitive Electrode Modified as a Pressure Sensor

Inter-digital capacitive electrodes working as electric field sensors have been developed for touch panel applications. Evaluation circuits to convert variations in electric fields in such sensors into computer compatible data are commercially available. We report development of an Interdigital capacitive electrode working as a sensitive pressure sensor in the range 0-120 kPa. Essentially it is a touch/proximity sensor converted into a pressure sensor with a suitable elastomer buffer medium acting as the pressure transmitter. The performance of the sensor has been evaluated and reported. Such sensors can be made very economical in comparison to existing pressure sensors. Moreover, they are very convenient to be fabricated into sensor arrays involving a number of sensors for distributed pressure sensing applications such as in biomedical systems.

An Integrated Hydro geological Study of the Muvattupuzha River Basin, Kerala, India

The present investigation on the Muvattupuzha river basin is an integrated approach based on hydrogeological, geophysical, hydrogeochemical parameters and the results are interpreted using satellite data. GIS also been used to combine the various spatial and non-spatial data. The salient finding of the present study are accounted below to provide a holistic picture on the groundwaters of the Muvattupuzha river basin. In the Muvattupuzha river basin the groundwaters are drawn from the weathered and fractured zones. The groundwater level fluctuations of the basin from 1992 to 2001 reveal that the water level varies between a minimum of 0.003 m and a maximum of 3.45 m. The groundwater fluctuation is affected by rainfall. Various aquifer parameters like transmissivity, storage coefficient, optimum yield, time for full recovery and specific capacity indices are analyzed. The depth to the bedrock of the basin varies widely from 1.5 to 17 mbgl. A ground water prospective map of phreatic aquifer has been prepared based on thickness of the weathered zone and low resistivity values (<500 ohm-m) and accordingly the basin is classified in three phreatic potential zones as good, moderate and poor. The groundwater of the Muvattupuzha river basin, the pH value ranges from 5.5 to 8.1, in acidic nature. Hydrochemical facies diagram reveals that most of the samples in both the seasons fall in mixing and dissolution facies and a few in static and dynamic natures. Further study is needed on impact of dykes on the occurrence and movement of groundwater, impact of seapages from irrigation canals on the groundwater quality and resources of this basin, and influence of inter-basin transfer of surface water on groundwater.

Fabrication Of Potentiometric Sensors For The Determination Of Certain Metal Ions

In this study Fabrication of Potentiometric sensors for the determination of certain metal ions, presents the synthesis and characterization of seven ionophores, their use in the fabrication of potentiometric sensors and the results and discussion of fourteen sensors developed for the determination of five transition metal ions. As part of the present investigations a total of fourteen potentiometric sensors have been developed and fabricated. A three fold approach has been taken in developing he sensors, PVC plasticized membrane sensor, carbon paste electrode and chemically modified carbon paste electrode. All the sensors are highly useful in the determination of metal ions such as manganese, nickel, copper, mercury and lead. A through analytical study has been carried out with respect to each other developed. Based on these studies, optimum conditions have been developed for the quantitative determinations of the selected metal ions using the sensors. Systematic application studies have also been carried out for all the developed sensors and the results revealed that the presently developed sensors are far superior than most of the sensors reported.

A PVC plasticized membrane sensor for nickel ions

A new PVC membrane sensor, which is highly selective towards Ni (II) ions, has been developed using a thiophene-derivative Schiff base as the ionophore. The best performance was exhibited by the membrane having the composition percentage ratio of 5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w=w), where NaTPB is the anion excluder, sodium tetraphenylborate and DBP is the plasticizing agent (dibutyl phthalate). The membrane exhibited a good Nernstian response for nickel ions over the concentration range of 1.0 10 1– 5.0 10 6M (limit of detection is 1.8 10 6 M) with a slope of 29.5 1.0mV per decade of activity. It has a fast response time of<20 s and can be used for a period of 4 months with good reproducibility. The sensor is suitable for use in aqueous solutions of a wide pH range of 3.2–7.9. The sensor shows high selectivity to nickel ions over a large number of mono-, bi- and trivalent cations. It has been successfully used as an indicator electrode in the potentiometric titration of nickel ions against EDTA and also for direct determination of nickel content in real samples – wastewater samples from electroplating industries and Indian chocolates.

A PVC Plasticized Membrane Sensor for Nickel Ions

A new PVC membrane sensor, which is highly selective towards Ni (II) ions, has been developed using a thiophene-derivative Schiff base as the ionophore. The best performance was exhibited by the membrane having the composition percentage ratio of 5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w=w), where NaTPB is the anion excluder, sodium tetraphenylborate and DBP is the plasticizing agent (dibutyl phthalate). The membrane exhibited a good Nernstian response for nickel ions over the concentration range of 1.0 10 1– 5.0 10 6M (limit of detection is 1.8 10 6 M) with a slope of 29.5 1.0mV per decade of activity. It has a fast response time of<20 s and can be used for a period of 4 months with good reproducibility. The sensor is suitable for use in aqueous solutions of a wide pH range of 3.2–7.9. The sensor shows high selectivity to nickel ions over a large number of mono-, bi- and trivalent cations. It has been successfully used as an indicator electrode in the potentiometric titration of nickel ions against EDTA and also for direct determination of nickel content in real samples – wastewater samples from electroplating industries and Indian chocolates.

A PVC Plasticized Sensor for Ni(II) Ion Based on a Simple Ethylenediamine Derivative

new PVC membrane ion selective electrode which is highly selective towards Ni(II) ions was constructed using a Schiff base containing a binaphthyl moiety as the ionophore. The sensor exhibited a good Nernstian response for nickel ions over the concentration range 1.0 × 10–1 – 5.0 × 10–6 M with a lower limit of detection of 1.3 × 10–6 M. It has a fast response time and can be used for a period of 4 months with a good reproducibility. The sensor is suitable for use in aqueous solutions in a wide pH range of 3.6 – 7.4 and works satisfactorily in the presence of 25% (v/v) methanol or ethanol. The sensor shows high selectivity to nickel ions over a wide variety of cations. It has been successfully used as an indicator electrode in the potentiometric titration of nickel ions against EDTA and also for the direct determination of nickel content in real samples: effluent samples, chocolates and hydrogenated oils.

A Chloride Ion-Selective Potentiometric Sensor Based on a Polymeric Schiff Base Complex

This paper describes the fabrication of an ion-selective electrode in which a polymeric Schiff base complex of cobalt(II) is used as the ionophore.The main advantage of the electrode is that it is mechanically stable upto 3 months..The electrode shows a linear response in the range of 2.5 × 10-5-0.5 × 10-1 mol dm-3. The response time of the electrode is 30 s.The pH range at which the electrode works is 3.8 to 6.8. The electrode was found to be selective towards chloride ion in the presence of ions like Na+, Ca2+, Mn2+, ,Fe3+, Co2+, Ni2+, Cu2+, Zn2+, CH3COO-, NO3-, SO42- ,Br- and NO2-.

Electrochemical Reduction and Voltammetric Determination of Metronidazole Benzoate at Modified Carbon Paste Electrode

A metalloporphyrin incorporated carbon paste sensor has been developed for the determination of metronidazole benzoate (MTZB). Zn(II) complex of 5,10,15,20-tetrakis (3-methoxy-4-hydroxy phenyl) porphyrin (TMHPP) was used as the active material. The MTZB gave a well-defined reduction peak at - 0.713V in 0.1 mol l -1 phosphate buffer solution of pH around 7. Compared with bare carbon paste electrode (CPE), the TMHPP Zn(II) modified electrode significantly enhanced the reduction peak current of MTZB as well as lowered its reduction potential. Under optimum conditions the reduction peak current was proportional to MTZB concentration over the range 1×10-3 mol1-1 to 1×10-5mol1-1. The detection limit was found to be 4.36×10-6mol1-1 . This sensor has been successfully applied for the determination of MTZB in pharmaceutical formulations and urine samples.

Synthesis,characterization and application studies of some polymer supported metal complexes

Polymer supports are efficient reagents,substrates and catalysts and they are extensively used for carrying out reactions at controlled rates.Tailor-made polymer supports are highly versatile which have opened an excellent area of research.Now polymer supported chemistry is being exploited at an amazing rate and it seems to join the routine world of organic synthesis.Polymer supported ligands are found to be efficient complexing agents whose high selectivity enables the analysis and removal of heavy metal ions which are toxic to all the living organisms of land and sea.polymer supported membranes function as ion selective potentiometric sensors which allow the exchange of specific ions among other ions of the same charge.In this investigation three series of polymeric schiff bases and three series of metal complexes have been prepared.An attempt is done to develop optimum conditions for the removal of heavy metal ions using polymeric schiff bases.A novel copper sensor electrode have also been prepared from polymer supported metal complex.

Synthesis, Characterization and Application Studies of Some Polymer Supported Metal Complexes

Polymer supports and polymeric complexes are highly versatile and they are successfully employed as efficient reagents, substrates and catalysts. Recently there observed a growing interest in the synthesis of tailor-made polymer supports and functionalized polymers for the preparation of metal complexes for various applications. They have the combination of properties due to the macromolecular structure as well as due to the reactivity of the functional group. An interesting feature of functional polymers is their affinity towards metal ions. Therefore the synthesis, characterization and application of such polymeric complexes have great scientific and analytical importance. In this investigation three series of polymeric complexes of transition metal ions are prepared from three schiff bases. All the complexes and polymeric schiff bases were characterized by analytical, spectral and thermal methods The thesis consist of six chapters. The first chapter contains an introduction and a brief review on application of polymer supports, polymer supported ligands and complexes. The second chapter gives the details of reagents and instruments used and the procedure adopted for the preparation of ligands and complexes. The third chapter explains the methods employed for characterization and the results are also discussed. The fourth chapter gives a detailed study of metal ion removal using ligands whereas the fifth chapter describes the development of the Cu” ion sensor electrode. The sixth chapter is the summary of the thesis and references are presented at the end.

Electrochemical studies of tamsulosin hydrochloride using multiwalled carbon nanotube-modified glassy carbon sensor

A differential pulse voltammetric sensor for the determination of tamsulosin hydrochloride (TAM) using multiwalled carbon nanotubes (MWNTs)–Nafion-modified glassy carbon electrode (GCE) has been developed. MWNTs were dispersed in water with the help of Nafion and were used to modify the surface of GCE via solvent evaporation. At MWNT-modified electrode, TAM gave a well-defined oxidation peak at a potential of 1084 mV in 0.1 M acetate buffer solution of pH 5. Compared to the bare electrode, the peak current of TAM showed a marked increase and the peak potential showed a negative deviation. The determination conditions, such as the amount of MWNT–Nafion suspension, pH of the supporting electrolyte and scan rate, were optimised. Under optimum conditions, the oxidation peak current was proportional to the concentration of TAM in the range 1 × 1023 M–3 × 1027 M with a detection limit of 9.8 × 1028 M. The developed sensor showed good stability, selectivity and was successfully used for the determination of TAM in pharmaceutical formulations and urine samples