A Carbon Nanotube Based Resettable Sensor for Measuring Free Chlorine in Drinking Water

A novel free chlorine sensor which uses oxidation of phenyl capped aniline tetramer (PCA T) to dope single wall carbon nanotube (SWCNT) and changes its resistance has been developed. The oxidation of PCAT by chlorine switches the PCAT-SWCNT system to low resistance (p-doped) state which is detected by probing it with a small voltage. The change in resistance is proportional to the concentration of the chlorine in the sample. The p-doped PCAT-SWCNT then can be electrochemically un-doped by polarizing it cathodically. This new sensor not only shows good sensing response in the whole concentration range of free chlorine in drinking water but also is able to be electrochemically reset back and can be used multiple times. This simple sensor is ideally suited for measuring free chlorine in drinking water continuously