EIS field effect structures functionalized by p-tert-butylcalix[6]arene for Ni2+ detection

In this work, we present the modification of above structures with a thin layer of p-tert-butyl-calix[6]arene deposited by spin-coating process. Capacitance and impedance measurements show that this sensitive thin films can be used to nickel detection. It is shown that developed chemical sensors with silicon nitride insulating substrate exhibit good stability due to the excellent adhesion of the film, high sensitivity and good selectivity. These interesting performances could not be achieved in the case of spin-coated p-tert-butyl-calix[6]arene thin layer on Si/SiO2 heterostructure treated in the same conditions. The results were simulated by an extended site binding model which carry out that the sensitivity of the sensor is due to electrochemical phenomena between the functionalized surface and the ions of the electrolyte. To analyze electrochemical impedance spectroscopy results and determine fundamental physical processes which govern the response of the system, an electrical equivalent circuit is proposed.