Optimization of the lateral field excited platform for liquid sensing applications

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Authors: C. Peters, R. Fernández, R. Lucklum, J. Fochtmann, D. McCann, J. Vetelino, A. Arnau

Journal: Procedia Engineering (2010)

 

The Lateral Field Excited (LFE) platform is sensitive to mechanical and electrical property changes occurring in adjacent media. Using the LFE sensor responses have been analyzed for the piezoelectric resonator materials alpha-quartz, lithium tantalate (LiTaO3) and lithium niobate (LiNbO3). Since the impact of the mechanical  load parameters on piezoelectric resonators is governed by the piezoelectric coupling factor, LiTaO3 and LiNbO3  are well suitable for operation in highly viscous environments. This benefit is achieved at the cost of a reduced sensitivity to the mechanical and electrical properties of the medium. A second approach proposes a new 3-electrode configuration. The response of this LFE sensor design to low electric permittivity has been modeled using a novel approach to simulate the low permittivity boundary conditions. An enhanced sensitivity of the sensor has been achieved.

High frequency mass transfer responses with polyaniline modified electrodes by using new ac-electrogravimetry device

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Authors: R. Torres, Y. Jiménez, A. Arnau, C. Gabrielli, S. Joiret, H. Perrot, T.K.L. To, X. Wang

Journal: Electrochimica Acta (2010)

For many years, polyaniline films have appeared to be one of the most studied conducting polymers. At the same time, ac-electrogravimetry has been used as a powerful technique for different polymer films but in general for slow perturbation rates. Two reasons for that: on the one hand, high frequency mass transfer responses are not expected and on the other hand, the electronic interfaces dedicated for ac-electrogravimetry are not prepared to follow, without distortion, high rate frequency shifts, faster than a few hertz. This paper shows that high ionic transfer responses can be detected by using a new ac-electrogravimetry concept. The experiments conducted with PANI tried to verify whether high frequency responses in conducting polymers are possible or not. The main interest of the new device is to reach the high frequency values directly and to demonstrate an ionic transfer contribution at 1 kHz which was not predicted with old systems.