The switch on-off response of a self-assembled monolayer (SAM) on a stimulating moiety such as a surfactant is interesting but not well known. Priority research attention has been paid to a special family of surfactant, fluorosurfactants, because they have been recently listed as emerging contaminants and persistent organic pollutants. Herein we investigate the electrochemical switch on-off response of a SAM of 6-(ferrocenyl, FC) hexanethiol (C-6-FC) upon exposure to perfluorooctanoic acid (PFOA), the most common fluorosurfactant. FC is employed as a redox probe to monitor the switch on-off response of the SAM formed on gold electrode surface. In an effort to understand the hydrophilic terminate group's influence from the surfactant, we dope the pristine C-6-FC SAM with 6-amino-1-hexanethiol (C-6-NH2), 1-hexanethiol (C-5-CH3), or 6-mercaptohexanoic acid (C-5-COOH) via a thiol-gold bond. We also dope it with 1-dodecanethiol (C-11-CH3) or 12-mercaptododecanoic acid (C-11-COOH) to investigate the length effect of the carbon chain. We observe there is a similar switch on-off response either from the presence of PFOA or from the doping C-6-COOH/C-11-COOH, suggesting the insertion of PFOA into the C-6-FC SAM, which is also evidenced by electrochemical quartz crystal microbalance (EQCM) and Raman spectrum. This research paves the way towards the development of aft electrochemical sensor and an approach for remediation of the fluorosurfactants. (C) 2016 Elsevier B.V. All rights reserved.