Precise detection of different species of chemical or biomolecules is fundamental to a vast variety of applications including medical science and environmental studies. Typically, a sensor is exposed to a sample to spot the possible existence of target molecules. The sample can be a gas or liquid possibly containing the target and even some other species. So, it may be required to make the sensor sensitive only to the proposed target molecules by functionalisation. Besides, achieving higher sensitivities is always appreciated. Some applications depend tightly on the time needed for the detection. Therefore, detection speed can be considered as a constraint. This factor can be affected by the type and number of stages involved in the detection procedure.
In order to satisfy the required sensitivity and speed, electrochemical transduction method was selected. Two different approaches are studied as the sensing mechanism. First, a suspended silicon nanowire is used as the channel of a field effect transistor. Then, by making two constriction areas on the nanowire, the architecture is transformed into a single-electron transistor at the heart of device. The single-electron transistor is utilised as an ultra-sensitive charge-based chemical or biosensor. Thus, the ability to sense even a single molecule is provided. In addition, more advanced designs of the single-electron transistor architecture are developed to avoid the necessity of using complex functionalisation methods. Moreover, using silicon on insulator as the implementation platform facilitates the integration of the sensor into the required control circuitry. This work is supported by EU FP7 NEMSIC project.