Review Contents Thermal Sensors 181R Mass Sensors 182R Electrochemical Sensors 182R Potentiometric Sensors 183R Amperometric Sensors 190R Conductometric Sensors 192R Optical Sensors 195R Conclusions 197R References 198RIn this review we are trying to cover the four-year gap in this series (A1). In this period, over 8278 references (in English only) have been retrieved from the Institute of Scientific Information database by the same search routine that was used previously. It represents 49% increase in the total. This relative increase alone attests to the vitality of the chemical sensing field. However, the absolute figures are somewhat distorted by the fact that many papers using term "sensors" really describe a sensing system (i.e., a chemical assay). Moreover, the trend to publish the same data several times, under a slightly modified title, has become a common practice in all fields of science, and chemical sensors are not an exception. As much as possible, we tried to use only one article from such multiple clusters. With this amount of information, it is only possible to scan the titles of the individual papers and then to select only approximately 10% for the final review. We hope that our colleagues whose paper is not cited understand that the decision to include or not to include a paper does not imply our judgment of the quality of that paper.It is interesting to see where are most chemical sensor papers published. From the papers included in this review, 17% appeared in Sensors and Actuators, B, 11% in Analytical Chemistry, 6% in Analytical Chimica Acta, 4% in Electroanalysis, and 3% in The Analyst. The remaining 60% is scattered throughout the literature. This surprisingly high figure indicates that the subject of chemical sensors is not a hobby of a few specialists but draws from a broad scientific and engineering base.Our aim has been to provide a critical assessment of the new trends, features, and distribution of effort in the entire chemical sensor field. This information is summarized in Table 1, which
