The design and development of a compact wireless gas sensor with a surface modified multiwalled carbon nanotube (f-CNT) chemiresistor as the sensing element is presented in this paper. f-CNT/polymer composite sensing film is patterned on a printed circuit board and is integrated to the wireless system. The change in resistance of the CNT/polymer composite film due to exposure of different gases is utilized as the principle of this gas sensor. The response for different organic vapors are evaluated and it is observed that the f-CNT/PMMA composite film shows fast response and change in resistance of the order of 10 2-10 3 due to its surface modification.

This paper relates for the first time, multiple resonant frequencies of fractal element antennas using Koch curves to their fractal dimension. Dipole and monopole antennas based fractal Koch curves studied so far have generally been limited to certain standard configurations of the geometry. It is possible to generalize the geometry by changing its indentation angle, to vary its fractal similarity dimension. This variation results in self-similar geometry which can be generated by a recursive algorithm. Such a variation is found to have a direct influence on the input characteristics of dipole antennas. The primary resonant frequency, the input resistance at this resonance, and the ratio of first two resonant frequencies, have all been directly related to the fractal dimension. Curve-fit expressions can also be obtained for the performance of antennas at their primary resonance, in terms of fractal iteration and fractal dimension. The antenna characteristics have been studied using extensive numerical simulations and are experimentally verified. These findings underscore the significance of fractal dimension as an important mathematical property of fractals that can be used as a design parameter for antennas. The use of these ideas would not only reduce the computational intensity of optimization approaches for design of fractal shaped antennas, but also help antenna designers approach the problem systematically. Design formulation for antennas based on other fractal geometries can be similarly obtained after identifying suitable parameters of variation. This would therefore help analytical design of multiband and multifunctional antennas using fractal geometries.Index Terms-Fractals, multifrequency antennas, wire antennas.

The design and development of composite thin films of polymethylmethacrylate (PMMA) with multiwalled carbon nanotubes (CNTs) and surface-modified multiwalled carbon nanotubes (f-CNTs) for gas-sensing applications are presented in this paper. The responses of these composites for different organic vapors were evaluated by monitoring the change in the resistance of thin films of composite when exposed to gases like dichloromethane, chloroform, acetone, methanol, ethyl acetate, toluene and hexane. It was observed that the f-CNT/PMMA composite showed a higher response. There was an increase in resistance of the order of 10 2 -10 3 , due to surface modification, when exposed to dichloromethane, chloroform and acetone. The sensing mechanism is explained on the basis of volume expansion and polar interaction of various vapors on the CNT surface.

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A nanocomposite of a multiwalled carbon nanotube and polythiophene was prepared by functionalizing the nanotube surface with a polythiophene, poly[3-(2-hydroxyethyl)-2,5-thienylene], containing pendant hydroxyl groups. The composite was characterized by IR, high resolution TEM and conductivity measurements. The poly[3-(2-hydroxyethyl)-2,5-thienylene] (PHET) was synthesized by the oxidation polymerization of 2-(3-thienylethanol) using FeCl3 and CHCl3. Multiwalled carbon nanotubes were synthesized by a microwave CVD method and oxidized with potassium permanganate using a phase transfer catalyst in mild conditions. The COOH groups formed on the nanotube surface were converted to COCl using thionyl chloride and it was then condensed with the polythiophene at high temperature in anhydrous DMF. High resolution TEM images showed that the functionalization provided a firm coating of the conducting polymer on nanotube walls. This nanocomposite with PHET grafted to CNT showed higher conductivity than a nanocomposite of PHET and CNT in the same percentage weight composition prepared by ultrasonic mixing of the two. Such a material was designed and synthesized with a view to electronic and sensor applications.

This paper presents the design and development of a passive wireless sensor for the detection of bio-hazard materials and vapors using chemiresistive thin films. Composite polymer thin film with functionalized carbon nanotubes (f-CNT) and polymethylmethacrylate (PMMA) is employed as a sensing material. It is investigated that resistance change is determined with the concentration of dichloromethane vapors diffused into composite thin film, due to electrical transition from direct contact to tunneling in carbon nanotube nanojunctions. The chemiresistive film is integrated into a passive wireless system which works based on the change in phase of the reflected RF signal. Measurement results of sensors in a wireless sensing system show a large differential phase shift, which can be utilized for remote monitoring of bio-hazard vapors in real time.

Design and experimental results of a surface acoustic wave (SAW) microsensor with polymer microfluidic cell for the sensing and identification of liquids is presented in this paper. This microsensor, which is a part of a smart tongue-nose system, uses a horizontally polarized SAW (SH-SAW) for the detection and identification of liquids. The SH-SAW microsensors are fabricated on 36 •-rotated Y-cut X-propagating LiTaO 3 (36Y X.LT) substrate. This design consists of a dual-delay-line configuration in which one line is free and other one is metallized and shielded. Polymer microfluidic cells were designed and fabricated on top of it using a microstereolithography system to avoid dielectric loading of the IDTs by liquid which leads to unwanted dielectric sensitivity to the sensor. Due to the high electromechanical coupling of the 36Y X.LT substrate, it could detect differences in electrical properties and hence distinguish different liquids. It is clear from these results that the microsensor based on 36Y X.LT is an effective liquid identification system for the electronic tongue application.

Remote patient monitoring is an alternative to comfort to the patient's life, it also allows a more realistic regular home check-ups of patients with certain special medical recording of the patient's health while performing normal conditions or the elderly who are unable to regularly visit a everyday activities. The system uses a configurable model for healthcare facility. This technology reduces the number of home ry . g visits which are now only required when special attention is theladdtion of onyte eired sensor fhe eci needed. This paper presents the design and development of a applications. It provides eight data acquisition channels, each remote point-of-care patient monitoring system which allows the with adjustable gain so that it can be adapted to various patient to be monitored remotely while remaining in the comfort sensors. A standard broadband Ethernet connection is used for of their home. The system described here allows wireless data remote communication with the care facility, thus eliminating acquisition from eight patient-worn sensors. The number and any need for special hardware or services.