Process chemical sensor development

Basic concepts, construction, and analytical application of chemical sensors. Development of theoretical problems coimected with the process of diffusion in ion-selective electrodes what enabled to decrease the limit of anal3tical detection for several orders of magnitude. Development of enzymatic biosensors for continuous control of the process of hemodialysis. 

Nowadays all over the world considerable attention is focused on development of chemical sensors for the detection of various organic compounds in solutions and gas phase. One of the possible sensor types for organic compounds in solutions detection is optochemotronic sensor - device of liquid-phase optoelectronics that utilize effect of electrogenerated chemiluminescence. In order to enhance selectivity and broaden the range of detected substances the modification of working electrode of optochemotronic cell with organic films is used. Composition and deposition technique of modifying films considerably influence on electrochemical and physical processes in the sensor. 

Even listing all above problems and requirements leading to their solution indicates that development of the method of semiconductor chemical sensors opens a wide research domain. In order to resolve this problems and implement all capabilities of the method of semiconductor sensors there are two ways now the old trial and error approach and approach related to further studies of physical and chemical properties of surface phenomena, reactions and processes underlying this method. It is quite clear that the second approach is more promising in order to obtain semiconductor sensors designed for the use in accurate scientific studies and for practical gas analysis. 

In parallel with improvements in chemical sensor performance, analytical science has also seen tremendous advances in the development of compact, portable analytical instruments. For example, lab-on-a-chip (LOAC) devices enable complex bench processes (sampling, reagent addition, temperature control, analysis of reaction products) to be incorporated into a compact, device format that can provide reliable analytical information within a controlled internal environment. LOAC devices typically incorporate pumps, valves, micromachined flow manifolds, reagents, sampling system, electronics and data processing, and communications. Clearly, they are much more complex than the simple chemo-sensor described above. In fact, chemosensors can be incorporated into LOAC devices as a selective sensor, which enables the sensor to be contained within the protective internal environment. Figure 5... 

Chemical sensors, those that measure the presence or concentration of chemical species, are the subject of this book. Until recently, they received even less attention than other sensors in general, they are not as well developed. They have the same need to be small, inexpensive, and accurate as other sensors. However, accomplishing these requirements for chemical sensors is often more difficult than for other sensors because chemical sensors are noted for interferences. For example, a chloride sensor may be sensitive to other halides. One popular way to counter this limitation is to use an array of somewhat different sensors, each responsive to the same set of related compounds but with different sensitivity. The output of the sensor array can be processed by a computer to give greater accuracy than a single sensor for the concentration of one compound. Unfortunately, this approach tends to gain better accuracy at the expense of increased size and cost. 

The possibilities of these approaches, considering the large numbers of potentially useful biochemical reactions, are enormous. It is expected that significant advances will occur in the field of biosensor development in the near future, especially when newer biotechnological processes and chemical modification approaches are adapted to sensor development. 

---