Chemiresistors based on ultrathin gold nanowires for sensing halides, pyridine and dopamine

Two distinctively different approaches to the deposition of the ultrathin gold nanowires (NWs) on chips for the development of the chemiresistor sensors are studied. The first approach is the deposition of the pre-synthesized NWs on a chip using a microfluidic technique, and the second is the direct synthesis of the NWs on chips. It is shown that the 2nd approach ensures a better contact between the NWs and electrodes, lower resistance of the NW sensor device, and a longer life time of the devices. The current-voltage dependencies obtained for the chips with the NWs in contact with air, and aqueous solutions of NaF, NaCl, NaBr, NaI, pyridine, and dopamine indicate significant changes of the NWs resistance caused by sorption of halides, pyridine and dopamine on the NWs surface. This change of the NWs resistance can be used for quantification of Cl− over a concentration range of 10−5–10−3 M and dopamine over a concentration range of 10−8–10−5 M. Tentatively, it is concluded that the data obtained can be explained in terms of the Langmuir adsorption isotherm