This volume, which addresses various basic sensor principles, covers micro gravimetric sensors, semiconducting and nano tube sensors, calorimetric sensors and optical sensors. Furthermore, the authors discuss recent developments in the related sensitive layers including new properties of nano structured metal oxide layers. They provide in-depth insights into the unique chemistry and signal generation of copper oxide in percolating sensors and present a variety of applications of functional polymers made possible by proper imprinting. Highlights of the subjects covered include: • requirements for high-temperature sensors • carbon nano tube sensors • new sensing model for nanostructured In2O3 • bio mimetic approach for semiconductor sensor-based systems • optical readout for inorganic and organic semiconductor sensors • concept of virtual multisensors to improve specificity and selectivity • calorimetric sensors for hydrogen peroxide detection • percolation effect-based sensors to implement dosimeters • imprinted polymer layers for bulk and surface acoustic wave sensors.