Microsensor applications

B. Panchapakesan, D.L. DeVoe, M.R. Widmaier, R. Cavicchi, and S. Semancik. Nanoparticle engineering and control of tin oxide microstructures for chemical microsensor applications , Nanotechnology 12 (2001), 336-349. 

The use of a graphite electrode, particularly glassy carbon, is also relatively limited in microfabricated electrochemical sensors. However, thick-film silk-screened graphite electrodes have been used in chemical sensor development, and the use of carbon fiber in microsensor applications has been reported. The purity of the graphite ink for thick-film silk screening is very critical to the performance of the sensor. 

OzaM Y, Suzuki S, Morimitsu M, Matsunaga M (2000) Enhanced long-term stability of SnO -based CO gas sensors modified by sulfuric acid treatment. Sens Actuators B Chem 62 220-225 Panchapakesan B, DeVoe DL, Widmaier MR, Cavicchi R, Steve SS (2001) Nanoparticle engineering and control of tin oxide microstructures for chemical microsensor applications. Nanotechnology 12 336-349 Papadopoulos CA, Vlachos DS, Avaritsiotis JN (1997) Effect of surface catalysts on the long-term performance of reactively sputtered tin and indium oxide gas sensors. Sens Actuators B Chem 42 95-101 Park CO, Akbar SA (2003) Ceramics for chemical sensing. J Mater Sci 38 4611-4637... 

R. Ehret, W. Baumann, M. Brischwein, M. Lehmann, T. Henning, I. Freund, S. Drechsler, U. Friedrich, M.-L. Hubert, E. Motrescu, A. Kob, H. Palzer, H. Grothe, and B. Wolf, Multiparametric microsensor chips for screening applications. J. Fresenius, Anal. Chem. 369, 30-35 (2001). 

R. Hintsche, C. Kruse, A. Uhlig, M. Paeschke, T. Lisec, U. Schnakenberg, and B. Wagner, Chemical microsensor systems for medical applications in catheters. Sens. Actuators B. B27, 471 —473 (1995). 

One of the most recent developments in the application of hydrogels have been in the field of microfluidics and microsensors. Peppas et al. (Bashir et al., 2002 Hilt et al., 2002) have successfully composed a... 

J.W. Gardner, Microsensors principles and applications, John Wiley Sons Ltd., Chichester, 1994. 

The sensitivity of hydrogels to a large number of physical factors like temperature [149], electrical voltage [150], pH [151-153], concentration of organic compounds in water [154], and salt concentration [155] make them promising materials for a broad range of applications as microsensors [156] and microactuators [154] in MEMS devices. 

Low-cost, disposable, Si02/Si3N4 chemical field effect transistor (ChemFET) microsensors have been fabricated for pH measurements and adapted to biochemical applications by using polyvinyl alcohol (PVA) enzymatic layers deposited and patterned... 

Gradient of dissolved 02 near a cluster of cells measured by micro oxygen electrode. [S.-K. Jung. J. R. Trimarchi. R. H. Sanger, and PJ. S. Smith. "Development and Application of a Self-Referencing Glucose Microsensor lor the Measurement of Glucose Consumption by Pancreatic i> Cells," Anat. Chem. 

S.-K. Jung, W. Gorski, C. A. Aspinwall, L. M. Kauri, and R. T. Kennedy, Oxygen Microsensor and Its Application to Single Cells and Mouse Pancreatic Islets, Anal. Chem. 1999, 71, 3642. 

Many problems and tasks, both scientific and technological, still remain in the field of gas sensors. For example, microsensors, intelligent sensors, cord-less sensors, etc., seem to be very important as well as attractive.- However, these are not covered here, and only trends in sensor application anticipated in the near future in Japan are pointed out below. 

In this paper, the application of microelectronic processing technology to the fabrication of SnOx and PdAu/SnOx microsensors on silicon wafers is described, sensor responses to various gases in air are presented, and the possible sensing mechanisms are briefly discussed. 

The creation of many effective combinations of artificial nose sensors with only a few functional monomers used in different relative amounts was proven here. The application of combinatorial technologies to the discovery of novel materials for more recent, miniamrized electronic nose systems based on small pol5mier beads (120), and to equally intriguing electronic tonguelike microsensors in solution to mimick the sense of taste for solution mixtures (121), should be highly beneficial and thus is to be expected in the near future. 

Zinc oxide (ZnO, wurtzite structure) eliminates oxygen on heating to form nonstoichio-metric colored phases, Zni+xO with x < 70 ppm. ZnO is almost transparent and is used as white pigment, polymer stabilizer, emollient in zinc ointments, creams and lotions, as well as in the production of Zu2Si04 for TV screens. A major application is in the rubber industry to lower the temperatures and to raise the rate of vulcanization. Furthermore, it is an n-type semiconductor (band gap 3.37 eV) and shows piezoelectric properties, making zinc oxide useful for microsensor devices and micromachined actuators. Other applications include gas sensors , solar cell windows and surface acoustic devices. ZnO has also been considered for spintronic application because of theoretical predictions of room-temperature ferromagnetism . 

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