Organic-based sensor for chemical detection in aqueous solution

We present a flexible, pentacene-based field-effect device, for the detection of chemical species in aqueous solution. The sensor consists in a double-gate transistor, where the detection is achieved by exploiting the charge sensing capabilities of the floating-gate terminal. To provide the pH-sensitivity, the floating gate is functionalized with thioamine groups as such groups protonize proportionally to the concentration of H3O+ ions in solution. With respect to the existing organic-based devices for pH monitoring, our sensor does not require a counterelectrode and the organic semiconductor is not affected by the contact with the monitored solution. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3232252]