Multichannel electrodes

Miniaturization, 128, 163, 193 Minigrid electrode, 41, 52 Mixed-salt electrodes, 159 Modified electrodes, 118, 121 Monensin, 155 Monolayers, 117, 118, 173 Multichannel electrodes, 93, 94 Multipotentiostat, 106, 198 Mutation detection, 185... 

Lipid membranes were fitted on a multichannel electrode. Figure 5 shows a front view and a cross section of the electrode. The electrode was made from Ag wires, which were 1.5 mm in diameter, embedded in a basal acrylic board. The lipid membranes cut into rectangle pieces were put on the Ag wires, and then the electrode was dried in air for 1 hour and dipped in 1 mM KC1 solution. 

Figure 4. Illustration of the surface state of the lipid-PVC membrane used in the multichannel electrode.

The used multichannel electrode was basically the same as that reported before, but was improved in a few respects. The detecting electrode of each channel was made up of Ag wires whose surface was plated with Ag/AgCl, which were embedded in a basal acrylic board of 2 mm thickness. Another acrylic board of 1 cm thickness which had eight cone-shaped holes was affixed to this board. The holes were filled with 100 mM KC1 solution, and the eight membranes were fitted on the board to cover the holes. 

Burian, K. et al.. Electrical stimulation with multichannel electrodes in deaf patients. Audiology, 1980,19 128 136. 

DiLorenzo, D.J., Unpublished Data on Microfabricated Multichannel Electrode Array for Retinal Stimulation, 1991, Massachusetts Institute of Technology. 

Terasawa Y, Tashiro H, Uehara A, Saitoh T, Ozawa M, Tokuda T, Ohta J (2006) The development of a multichannel electrode array for retinal prostheses. Journal of Artificial Organs 9 263-266, URL http //dx.doi.org/10.1007/sl0047-006-0352-1, 10.1007/sl0047-006-0352-1... 

FIGURE 3-27 Three-dimensional chromatogram for oxidizable biological compounds at a multichannel amperometric detection system, consisting of an array of 16 carbon-paste electrodes held at different potentials. AA = ascorbic acid NE = norepinephrine DOPAC = 3,4-dihydroxyphenylacetic acid 5-HIAA = 5-hydroxyindole-3-acetic acid DA = dopamine HVA = homovanillic acid. (Reproduced with permission from reference 68.)... 

Figure 13. (a) Experimental approach for simultaneous collection of potential and current noise, (b) Schematic for remotely controlled impedance and noise multichannel data collection system. (Reprinted from F. Mansfield, C. Chen, C. C. Lee, and H. Xiao, The Effect of Asymmetric Electrodes on the Analysis of Electrochemical Impedance and Noise Data, Corros. Sci. 38 (3) 497, Fig. 1. Copyright 1996 with permission of Elsevier Science.)...

Fig. 1. Schematic diagram of the multimass ion imaging detection system. (1) Pulsed nozzle (2) skimmers (3) molecular beam (4) photolysis laser beam (5) VUV laser beam, which is perpendicular to the plane of this figure (6) ion extraction plate floated on V0 with pulsed voltage variable from 3000 to 4600 V (7) ion extraction plate with voltage Va (8) outer concentric cylindrical electrode (9) inner concentric cylindrical electrode (10) simulation ion trajectory of m/e = 16 (11) simulation ion trajectory of rri/e = 14 (12) simulation ion trajectory of m/e = 12 (13) 30 (im diameter tungsten wire (14) 8 x 10cm metal mesh with voltage V0] (15) sstack multichannel plates and phosphor screen. In the two-dimensional detector, the V-axis is the mass axis, and V-axis (perpendicular to the plane of this figure) is the velocity axis (16) CCD camera.

Some commercially available detectors have a number of detection modes built into a single unit. Fig. 2.4o is a diagram of the detector used in the Perkin Elmer 3D system, which combines uv absorption, fluorescence and conductivity detection. The uv function is a fixed wavelength (254 nm) detector, and the fluorescence function can monitor emission above 280 nm, based on excitation at 254 nm. The metal inlet and outlet tubes act as the electrodes in the conductance cell. The detection modes can be operated independently or simultaneously, using a multichannel recorder. In the conductivity mode, using NaCl, a linear range of 103 and a noise equivalent concentration of 5 x 10 8 g cm-3 have been obtained. 

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. 

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. 

The apparatus needed for the experiments are a multichannel pH/ mV meter (for example, the six-channel Consort C864 multiparameter analyser), a double junction Ag AgCl reference electrode, (for example, Orion 90-02) and a magnetic stirrer. 

Fig. 16. Multichannel cuff electrode with four tripoles...

ESPRIT, 8897). The regeneration of a dissected nerve through a sieve was investigated in an animal model at the sciatic nerve of rats. The basic components of the implant are illustrated in Fig. 18 a multichannel sieve electrode with long integrated interconnections, two guidance channels, and the nerve stumps that were inserted very carefully into the channels. The sieve electrode was fabricated with the single-metallization layer process described above. 

Fig. 18. Schematic of a flexible multichannel sieve electrode with integrated interconnections...

IET serves as a theoretical basis not only for fluorescence and photochemistry but also for photoconductivity and for electrochemiluminescence initiated by charge injection from electrodes. These and other related phenomena are considered. The kinetics of luminescence induced by pulse and stationary excitation is elucidated as well as the light intensity dependence of the fluorescence and photocurrent. The variety and complexity of applications proves that IET is a universal key for multichannel reactions in solutions, most of which are inaccessible to conventional (Markovian) chemical kinetics. 

Acetylcholineesterase Miniaturized multichannel transduc-tor with planar Au electrode which was first covered with a choline-selective liquid membrane made from 66% PVC-polyvinyl acetate (PVA), 33% 2-nitrophenyl octyl ether plasticizer and 1% ion-pair choline phosphotungstate. A second layer of 2% AChE in the PVA-polyethylene dispersion was spread on the top. The electrode was used as working electrode versus Ag/AgCl for potentiometric measurement of Ch and ACh in 0.1 M Tris buffer at 7.4. Optimum pH range for the sensor was 7-9. The calibration graph was linear from 0.02-10 mm ACh and detection limit was 5 pM. Response time was 3-5 min. Sensor was suitable for determination of ACh in biological fluids. [86]... 

---