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One of the most widely known effects in nano electronics is the Coulomb-blocked effect which reduces the shot noise in a device. However, the effect of shrinking of the size is not always so beneficial, shot noise can even increase, because of other effects. Moreover, other types of noises and new effects can set strong limits for device performance. From classical knowledge on device noise, an increased 1/f noise and increased effective thermal noise voltage and quantum uncertainty noises are expected which imply performance limitations at the low frequency and high frequency ends, respectively. The results is a reduced long-term stability an increased frequency of false-bit-switching or false alarm events. These considerations can help us to understand why biology is using neural spikes. From the research-and- development side, the original and engineering of conductance noise is often an unsolved problem. For example, in carbon nanotubes, the published experimental results are contradictory and it is not possible to draw a final conclusion about the nature and possible ways of engineering this crucial kind of noise source. It is important to realize that more active noise sources do not always mean limitation of performance. In chemical sensing applications, the measurement of noise can be used to detect chemical agents and their composition with a great selectivity and sensitivity, because the chemical fragments dynamically interact with the current transport in the device. This is the situation when the noise in nano-sensors has a great advantage as compared to the noise in classical devices. The increased specific surface of nanostructures and the large number of possible structural combinations have a great potential for both gas and fluid sensing application s via noise analysis.
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