Pierre-Henri Ducrot

Optimization Of PVDF-TrFE Processing Conditions For The Fabrication Of Organic MEMS Resonators.

This paper reports a systematic optimization of processing conditions of PVDF-TrFE piezoelectric thin films, used as integrated transducers in organic MEMS resonators. Indeed, despite data on electromechanical properties of PVDF found in the literature, optimized processing conditions that lead to these properties remain only partially described. In this work, a rigorous optimization of parameters enabling state-of-the-art piezoelectric properties of PVDF-TrFE thin films has been performed via the evaluation of the actuation performance of MEMS resonators. Conditions such as annealing duration, poling field and poling duration have been optimized and repeatability of the process has been demonstrated.

Integrated Electromechanical Transduction Schemes for Polymer MEMS Sensors

Polymer Micro ElectroMechanical Systems (MEMS) have the potential to constitute a powerful alternative to silicon-based MEMS devices for sensing applications. Although the use of commercial photoresists as structural material in polymer MEMS has been widely reported, the integration of functional polymer materials as electromechanical transducers has not yet received the same amount of interest. In this context, we report on the design and fabrication of different electromechanical schemes based on polymeric materials ensuring different transduction functions. Piezoresistive transduction made of carbon nanotube-based nanocomposites with a gauge factor of 200 was embedded within U-shaped polymeric cantilevers operating either in static or dynamic modes. Flexible resonators with integrated piezoelectric transduction were also realized and used as efficient viscosity sensors. Finally, piezoelectric-based organic field effect transistor (OFET) electromechanical transduction exhibiting a record sensitivity of over 600 was integrated into polymer cantilevers and used as highly sensitive strain and humidity sensors. Such advances in integrated electromechanical transduction schemes should favor the development of novel all-polymer MEMS devices for flexible and wearable applications in the future.

Electronic scheme for full control of organic piezoelectric MEMS resonators

This work deals with an acquiring system dedicated to the measurement of the resonance frequency and the quality factor of organic piezoelectric resonators. These resonators consist of a free-standing cantilever and its non-released counterpart used to compensate electrical signals that are not due to mechanical behavior. The system uses a capacitive half-bridge with two AC voltages in opposite phases, associated with an IQ demodulator. The magnitudes of the two AC voltages can be set independently from one another, which enables a powerful compensation of parasitic capacitance. Thanks to this dedicated system, measurements of the resonance frequency of organic piezoelectric resonators both in air and liquid media have been performed. Several methods to determine accurately the resonance frequency have been tested and compared in terms of measurement noise.