Cyclodextrin-polymethylhydrosiloxane gel as sensitive membrane for heavy ion sensors

Membrane gels obtained by chemically grafting cyclodextin (CD) molecules on polymethylhydrosiloxane (PMHS) is for used as heavy ion sensors. The sensitivity of the membranes, deposited on silicon-silica structure and used as a work electrode in an electrochemical cell, depends on the nature of both ions and ionophores. The variation of the concentration of Cd(II) or Pb(II) ions in the electrolyte (10−6.5–10−3 M) induces a shift of the flat-band voltage and in some cases, a modification of the accumulation capacitance of this electrolyte/insulator/semiconductor structure. The Nernstian responses of an α-CD membrane towards Cd(II) ion and of the β-CD towards Pb(II) ion, was observed. Similar results were obtained when CD molecules are incorporated into plasticized polyvinylchloride (PVC) membranes.