Development of potentiometric ion sensors based on insertion materials as sensitive element

We have demonstrated the feasibility of developing stable Li + potentiometric sensors, using a composite plastic technology as electrode support. Both triphylite LiFePO 4- and FePO 4-based sensors display good Li + sensing properties (reversibility, stability, linearity in the serum Li + concentration range). Besides, the reversible insertion of various cations (Na +, K +, Mg 2+) into the FePO 4 host structure was unraveled, providing the necessary information to clearly demonstrate that, within these materials, the sensing mechanism is nested in the ability of the structure to undergo cation insertion/deinsertion reactions. This process was shown to be governed by the Nernst's law. To our knowledge, besides the LiMn 2O 4/MnO 2 spinel-type system, the LiFePO 4/FePO 4 constitutes the second example of a sensor based on this mechanism.