Total analysis system sensor

Ito, T., Sobue, K., Ohya, S., Water glass bonding for micro-total analysis system. Sensors Actuators B 2002, 81, 187-195. 

The need for improved sensor performance has led to the emergence of micro and nanofluidics. These fields seek to develop miniaturized analysis systems that combine the desired attributes in a compact and cost-effective setting. These platforms are commonly labeled as labs-on-chip or micro total analysis systems (pTAS)2, often using optical methods to realize a desired functionality. The preeminent role that optics play has recently led to the notion of optofluidics as an independent field that deals with devices and methods in which optics and fluidics enable each other3. Most of the initial lab-on-chip advances, however, occurred in the area of fluidics, while the optical components continued to consist largely of bulk components such as polarizers, filters, lenses, and objectives. 

Several techniques for miniaturization of simple chemical and medical analysis systems are described. Miniaturization of total analysis systems realizes a small sample volume, a fast response and reduction of reagents. These features are useful in chemical and medical analysis. During the last decade many micro flow control devices, as well as the micro chemical sensors fabricated by three dimensional microfabrication technologies based on photofabrication, termed micromachining, have been developed. Miniaturized total analysis systems (pTAS) have been studied and some prototypes developed. In microfabricated systems, microfluidics , which represent the behavior of fluids in small sized channels, are considered and are very important in the design of micro elements used in pTAS. In this chapter microfluidics applied flow devices, micro flow control devices of active and passive microvalves, mechanical and non-mechanical micropumps and micro flow sensors fabricated by micromachining are reviewed. 

Keywords Microfluidics, micro total analysis system (pTAS), microvalve, micropump, micro flow sensor. 

Micro flow control devices open new possibilities for the miniaturization of conventional chemical and biochemical analysis systems. The micro total analysis system (pTAS) including microfabricated detectors (e.g. silicon based chemical sensors, optical sensors), micro flow control devices and control/detec-tion circuits is a practical micro electro mechanical system (MEMS). pTAS realize very small necessary sample volume, fast response and the reduction of reagents which is very useful in chemical and medical analysis. Two approaches of monolithic and hybrid integration of these devices have been studied. Monolithic and hybrid types of flow injection analysis (FIA) systems were already demonstrated [4, 5]. The combination of the partly integrated components and discrete components is useful in many cases [6]. To fabricate such systems, bonding and assembling methods play very important roles [7]. 

The concept of an total analysis system (TAS) was presented early by Widmer [87] and was extended to a pTAS concept by Manz [88]. In contrast to sensor systems such systems are based on unspecific sensors gaining the selectivity by separation principles. Electrophoresis devices are good candidates for miniaturization saving time and reducing production costs. Further details are given in various chapters in this book. 

Bergveld, P., Bedside clinical chemistry from catheter tip sensor chips towards micro total analysis systems. Biomed. Microdevices 2000, 2(3), 185-195. 

Guenat, O.T., Ghiglione, D., Morf, W.E., de Rooij, N.F., Partial electroosmotic pumping in complex capillary systems Part 2 Fabrication and application of a micro total analysis system (TAS) suited for continuous volumetric nanotitrations. Sensors Actuators B 2001, 72, 273-282. 

Sohn, Y.-S., Goodey, A.P., Anslyn, E.V., McDevitt, J.T., Shear, J.B., Neikirk, D.P., Development of a micromachined fluidic structure for a biological and chemical sensor array. Micro Total Analysis Systems, Proceedings 5th TTAS Symposium, Monterey, CA, Oct. 21-25, 2001, 177-178. 

Weigl, B.H., Kriebel, J., Mayes, K., Yager, P., Wu, C.C., Holl, M., Kenny, M., Zebert, D., Simultaneous self-referencing analyte determination in complex sample solutions using microfabricated flow structure (T-sensors). Micro Total Analysis Systems 98, Proceedings pTAS 98 Workshop, Banff, Canada, 13-16 Oct. 1998, 81-84. 

Hinkers, H., Conrath, N., Czupor, N., Frebel, H., Htiwel, S., Kockemann, K., Trau, D., Wittkampf, M., Chemnitius, G., Haalck, L., Meusel, M., Cammann, K., Knoll, M., Spener, F., Rospert, M., Kakerow, R., Koster, O., Lerch, T., Mokwa, W., Woias, P., Richter, M., Abel, T., Mexner, L., Results of the development of sensors and pTAS-modules. Micro Total Analysis Systems 96, Proceedings of 2nd international Symposium on pTAS, Basel, 19-22 Nov. 1996, 110-112. 

Bousse, L., McReynolds, R., Micromachined flow-through measurement chambers using LAPS chemical sensors. Micro Total Analysis Systems, Proceedings pTAS 94 Workshop, University of Twente, Netherlands, 21-22 Nov. 1994, 127-138. 

Semiconductor nanocrystals are being used as fluorescent biological labels. It is likely that sensors based on nanotechnology will revolutionize health care, climate control and detection of toxic substances. It is quite possible that we will have nanochips to carry out complete chemical analysis. Such nano-total analysis systems will have to employ new approaches to valves, pipes, pumps, separations and detection. 

Ohori T, Shoji S, Miura K, Yotsumoto A. Partly disposable three-way microvalve for a medical micro total analysis system (JAS). Sensors Actuators A 1998 64 57-62. 

Miniaturization and integration of sensors into lab on a chip total analysis systems are likely to have very important implications in medical diagnostics and microanalysis of complex mixtures. The breakthroughs here have involved microfluidics and laser-induced fluorescence techniques, as well as ultramicroelectrodes tor ultrasensitive electrochemical analysis. 

E. Verpoorte, A. Manz, H. Lndi, A. E. Bruno, F. Maystre, B. Krattiger, H. M. Widmer, B. H. Vanderschoot, and N. F. Derooij, A Silicon Flow Cell for Optical-Detection in Miniaturized Total Chemical-Analysis Systems, Sensors and Actuators B-Chemical, vol. 6, no. 1-3, pp. 66-70, Jan. 1992. 

Verpoorte, E., Manz, A., Ludi, H., Bruno, A.E., Maystre, R, Krattiger, B., Widmer, H.M., Van-derschoot, B.H., and Derooij, N.R, A silicon flow cell for optical-detection in miniaturized total chemical-analysis systems, Sensors and Actuators B—Chemical, 6, 66-70, 1992. 

On the other hand, microfluidic devices for lab-on-a-chip applications are mainly used in the context of analysis and diagnostics, often integrated in soolled miniaturized total analysis systems (p-TAS) [2]. The fundamental idea of p-TAS is to integrate all analytical steps such as sampling, sample pretreatment, analyte separation and detection for qualification or quantification within one device. Depending on the complexity of the sample, a lab-on-a-chip device can be a simple sensor, a flow-injection analysis (p-FIA) or a complete analytical separation device such as a chromatographic (p-HPLC) or a capillary electrophoresis (p-CE) system [3]. 

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