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Device chemiresistor

A chemical microsensor can be defined as an extremely small device that detects components in gases or Hquids (52—55). Ideally, such a sensor generates a response which either varies with the nature or concentration of the material or is reversible for repeated cycles of exposure. Of the many types of microsensors that have been described (56), three are the most prominent the chemiresistor, the bulk-wave piezoelectric quartz crystal sensor, and the surface acoustic wave (saw) device (57). [Pg.396]

One of the simplest, albeit least discussed, chemiresistors is the mercury vapor sensor. The heart of this device is a thin (7-40 nm) film of gold evaporated on a ceramic or glass substrate. At such thicknesses, the films are continuous, with the resistivity between 300 and l,500Qcm. The sensors are usually connected as a pair in a DC bridge configuration with one sensor acting as the reference. [Pg.248]

H. E. Katz, Chemically Sensitive Field-efFect Transistors and Chemiresistors New Materials and Device Structures , Electroanalysis 16, 1837 (2004). [Pg.419]

It is important to stress that the best results are obtained in the pulse mode because continuous biasing is not generally well tolerated by organic devices and small analyte response can be masked by current drifts. The level of performance currently achieved with OTFT sensors exhibits responses of 5-15% for analyte concentrations of 10-100 ppm and response times of 3-5 s. All this makes OTFT sensors a promising technology able to compete with chemiresistors in sensor arrays. [Pg.518]

OTFT response repeatability and enhancement, achieved with the gate bias, are apparent advantages over traditional chemiresistor sensors, whose response is a single parameter without any possibility to be modified. A resistor is a two-terminal device giving a resistive response, which is completely determined by the bnlk properties of the material used. It is of particular interest to investigate whether, besides a response enhancement, OTFTs are able to deliver a sensitivity enhancement no clear evidence of this phenomenon has been given and it is not yet well nnderstood which parameters control this important analytical property in OTFT sensors. [Pg.519]

Fig. 5.2. Schematic of a typical chemiresistor device using interdigitated electrodes. There are two steady state conditions during operation (1) no analyte present in the sampling environment and (2) analyte present in the sampling environment... Fig. 5.2. Schematic of a typical chemiresistor device using interdigitated electrodes. There are two steady state conditions during operation (1) no analyte present in the sampling environment and (2) analyte present in the sampling environment...
An integrated chemiresistor based on an SWCNT network was reported by NASA Ames Research Centre (Li et al, 2005). The device was composed... [Pg.363]

Traces of VOCs in human breath can be a symptom of diabetes, kidney failure, asthma or breast cancer. VOCs were mainly detected by mass spectroscopy with a ppb detection limit. The most advanced VOC sensor based on SWCNTs for medical application was introduced by Peng et al. (2008a, 2008b). This device is designed as an array of ten SWCNT chemiresistors coated with different non-polymeric organic layers. Since the responses of each chemiresistor are different, a principal component analysis of the measurement allows the direct discrimination between a healthy patient and a patient with cancer or renal diseases. The same authors have also highlighted the dramatic effect of humidity on the sensor response and have proposed coupling the device with a water extractor (Fig. 10.8). [Pg.379]

In biomedical sensing, some of the solid-state devices based on thermal sensing cannot be used effectively. The reason is that the sensor itself has to be heated or is heated quite hot by catalytic surface reactions. Thus pellistors (oxides with catalytic surfaces and embedded platinum wire thermometer), chemiresistors, and Figaro sensor smoke detectors have not found many biologic applications. [Pg.111]

Under ambient conditions, SWNTs are p-type semiconductors. This means that the charge carriers are holes, or the absence of electrons. This class of semiconductors shows an increase in conductivity when electron density is withdrawn and a decrease in conductivity when electron density is donated. This behavior has been observed experimentally for individual SWNTs connected to a set of electrodes. This allows for chemical detection with a simple chemiresistor. This is a device composed of two electrodes which are connected by some material, in this case a single-walled carbon nanotube, which changes resistance upon exposure to a particular analyte. [Pg.62]

Moreover, prototype devices of chemiresistor microsensors demonstrated the performance for detecting... [Pg.4992]

Electrical conduction is also very important for many devices that exploit the huge area of surface or interface per unit volume in zero-dimensional nanostructured materials such as nanoporous materials, granular materials, nanocomposites, and nanoparticle assemblies. Examples of such devices are chemiresistor-type sensors, solar cells, light-emitting diodes, and energy-storage cells. From the point of view of electron... [Pg.1043]

Through the study of nanoporous Pd films described in Chap. 4 (Vol. 1), it was demonstrated that the detection limit and response time could be improved in nanoporous structures with increased sirface area and decreased distance for bulk diffusion. Taking into account mentioned above, one can conclude that films from metal nanoparticles and metal nanowires would be ideal structures for fast detection of low gas concentrations. Experiment has shown that this assumption is valid and noble metal nanoparticles can be successfully incorporated into gas sensors. The selection of noble metals such as Au and Pt for gas sensor fabrication is based on their chemical inertness (Dovgolevsky et al. 2009). It was established that, compared to conventional metal oxide chemiresistors, MNP-based devices have the advantage that they can be operated at room temperature or slightly above, which enables easy device integration and low-power operation (Joseph et al. 2008 Saha et al. 2012). [Pg.73]

Ogawa T, Kobayashi K, Masuda G, Takase T, Maeda S (2001) Electronic conductive characteristics of devices fabricated with 1,10-decanedithiol and gold nanoparticles between 1-m electrode gaps. Thin Solid Films 393 374-378 Pang P, Guo Z, Cai Q (2005) Humidity effect on the monolayer-protected gold nanoparticles coated chemiresistor sensor for VOCs analysis. Talanta 65 1343-1348 Pileni MP (1993) Reverse micelles as microreactors. J Phys Chem 97 6961-6973... [Pg.89]

New developments can be envisaged from the interesting results on derivatized microelectrodes that can work as microelectronic devices when immersed in an electrolyte solution. The operation of these chemiresistors is due to different physical properties in the oxidized or reduced states of the polymers compared with the neutral state. The general route described below should be applicable to a wide variety of metal/polymer/metal as well as metal/polymer 1/polymer 2/metal interfaces. [Pg.192]

Some differences from solid-state MOSFETs must be noted. For the wet system (chemiresistors), the rate depends on the chemical reaction (intercalation of anions) potentials are referred to a reference electrode channel thickness of the solid-state devices is smaller than the thickness of the polymer coating the I-V characteristics are expressed by Vj, vs Ij,. [Pg.194]


See other pages where Device chemiresistor is mentioned: [Pg.396]    [Pg.242]    [Pg.257]    [Pg.237]    [Pg.201]    [Pg.142]    [Pg.508]    [Pg.508]    [Pg.510]    [Pg.396]    [Pg.143]    [Pg.150]    [Pg.151]    [Pg.152]    [Pg.363]    [Pg.370]    [Pg.378]    [Pg.378]    [Pg.32]    [Pg.33]    [Pg.355]    [Pg.228]    [Pg.1497]    [Pg.1498]    [Pg.239]    [Pg.460]    [Pg.461]    [Pg.18]    [Pg.19]    [Pg.51]    [Pg.181]    [Pg.32]    [Pg.71]    [Pg.186]   
See also in sourсe #XX -- [ Pg.7 ]

See also in sourсe #XX -- [ Pg.7 ]




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