Multichannel sensors

Although the above lipid membranes had the ability to sense the taste by responding to many taste substances, information was insufficient to recognize quality of the taste. This weakness was overcome by means of a multichannel sensor, where transducers were composed of lipid membranes immobilized with a polymer [16-23]. We investigated responses of the sensors to various taste solutions. The electrode showed five different response patterns to five primary tastes with small experimental deviations. The patterns looked alike when the applied substance elicited the same taste in humans. 

Figure 8. Responses of the multichannel sensor to five taste qualities. The origin of the electrical potential was taken to 1 mM KC1.

Keywords Data processing Multichannel sensors Noise analysis Optical sensor Sensor instrumentation Spectroscopy of surface plasmons SPR imaging ... 

The limb prostheses of the future will be equipped with multichanneled sensors that send tactile and proprioceptive feedback to the brain, continuously informing it about the effector s function. This approach wiU improve the patient s sense of ownership of the artificial limb. 

Fig. 13.3 Examples of screen-printed electrochemical sensors suitable for the construction of immunosensors. Options include 1, 2, 4 and 8 working electrodes (available materials Au, Pt, graphite), silver reference (Ag, Ag/AgCl) and auxiliary electrodes. Multichannel sensors produced according to our designs by BVT Technologies...

USCT IT. The US block forms beam data by the mirror-shadow method and ensures simultaneously precise measurement of coordinates of sensors. It consists of two multichannel blocks, namely tomographic (USTB) for multiangle collection of projection data and coordinate (USCB) on surfaces waves for coordinates measurement of US sensors. 

M.N. Tib and R. Narayanaswamy, Multichannel calibration technique for optical-fibre chemical sensor using artificial neural network. Sensors Actuators, B39 (1997) 365-370. 

After each series of experiments with beams of various intensity the section plate would be removed from the cell and disassembled, with radioactive silver washed out by nitric acid. Radioactivity of the solutions obtained was measured by a multichannel spectrometric scintillation y-counter with sensitivity of up to 10 G, i. e. around 10 of atoms which, according to calculations, is 10 times lower than sensitivity of ZnO sensor 10 G or 10 of Ag atoms respectively [28]. This difference in sensitivity lead to great inconveniences when exposing of targets was used in above methods. Only a few seconds were sufficient to expose the sensor compared to several hours of exposure of the scintillation counter in order to let it accumulate the overall radioactivity. It is quite evident that due to insufficient stability during a long period of exposure time an error piled up. 

Ymeti A., Kanger J.S., Greve J., Lambeck P.V., Wijn R., Heideman R.G., Realisation of a multichannel integrated Young interferometer chemical sensor., Appl. Opt 2003 42 5649-5660. 

P. Skladal and T. Kalab, A multichannel immunochemical sensor for determination of 2,4-dichloroph-enoxyacetic acid. Anal Chim. Acta 316, 73-78 (1993). 

In addition to absolute pressure measurements, pressure sensors can be used to determine flow rates when combined with a well-defined pressure drop over a microfluidic channel. Integration of optical waveguide structures provides opportunities for monitoring of segmented gas-liquid or liquid-liquid flows in multichannel microreactors for multiphase reactions, including channels inside the device not accessible by conventional microscopy imaging (Fig. 2c) (de Mas et al. 2005). Temperature sensors are readily incorporated in the form of thin film resistors or simply by attaching thin thermocouples (Losey et al. 2001). 

A YI can be designed to have more than two channels. As the two-channel YI sensor is a special case of the more general /V-channel or multichannel YI, the theory of the YI is treated for the general /V-channel YI. As shown in this section, in the multichannel YI all pairs of parallel output channels act as a two-channel YI, each with a unique distance between its two arms. In Fig. 10.5 the layout of the 4-channel YI sensor described in this chapter is shown. 

A more detailed description of the working principle of the multichannel YI is given for a four-channel device (N = A). The distances between the channels have been chosen such that di2 k d23 i=- d34 / di3 =/= d24 / dl4. There are six possible different channel pairs corresponding to six different distances of dx2 = 60 pm, d23 = 80 pm, d34 = 100 pm, d13 = 140 pm, d24 = 180 pm, and d14 = 240 pm. These distances match the realized YI sensor structure described in Sect. 10.3. The final interference pattern will thus be a superposition of six two-channel interference patterns. The calculated interference pattern for the four-channel YI is shown in Fig. 10.6a. The amplitude spectrum (lower graph) and the phase spectrum (upper graph) of the Fourier-transformed interference pattern are presented in Fig. 10.6b. 

The WDMSPR sensor approach offers the benefit of multichannel performance without increasing complexity and costs of the sensor system. In addition, the WDMSPR sensors make it possible to discriminate effects occurring in the proximity of sensor surface (specific binding, non-specific adsorption) from those occurring in the whole medium (interfering background refractive index fluctuations) which is a prerequisite for robust referencing ". ... 

Hayashi, K., Yamanaka, M., Toko, K., and Yamafuji, K. (1990). Multichannel taste sensor using lipid membranes. Sens. Actmtors B 2, 205-213. 

The relationship between the concentration of L-Glu and the response as an integrated channel current for the multichannel-type sensor (most likely containing >10 GluR ion channel proteins) is shown in Figure 26a. A sharp concentration dependence was observed up to ca. 1.5 x 10" M of L-Glu. The detection limit of this sensing system is lower than the lowest concentration tested, i.e., 3.0 x 10" M. 

Rantanen J, Lehtola S, Ramet P, Mannermaa JP, Ylirussi J. On-line monitoring of moisture content in a instrumented fluidized bed granulator with multichannel NIR moisture sensor. Powder Technol 1998 99 163-170. 

Use of bilayer lipid membranes as a generic electrochemical transducer is an exciting future for food biosensors. A taste sensor with multichanneled lipid membrane electrode was recently developed (93). The electric patterns generated from the sensor are similar to human response. The sensor can distinguish different brands of beer. More details on the taste sensor can be found in Chapter 16 of this book. 

The DOPH membrane and the ammonium salt membrane responded to taste substances in different ways. The above results suggest that taste substances can be perceived satisfactorily using various kinds of lipid materials. Furthermore, we must improve the sensing reproducibility. As a second step, we have developed a multichannel lipid membrane taste sensor. Taste substances can be discriminated by the output pattern from several lipid membranes. 

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