The FUNCHIP project aims to determine the physical limits of parallel plate electrostatic actuators used in MEMS RF switches, and optimize the thermal behavior of these components. Applications targeted in this project include active antennas for Radars, in which RF - MEMS relays would protect the RF front heads efficiently, while having reduced losses. Technological roadbloacks concern power handling , which must be greater than 20 Watts between 6 and 20 GHz , with over 1 Billion cycles reliabilities . With the maturation of research in this area, the keys for achieving such performance are emerging. The electrostatic actuator which is used for opening and closing the relays must generate large forces. This allows using very stiff, fast structures, and insensitive to adhesion. Furthermore, the resistance between the two electrodes when the relay is closed, is lower when the pressure is important. For a given power level , the temperature elevation at the contact point is related to the resistance of this point (and therefore to the force generated by the actuator ) , but also to the ability of the substrate to remove the heat generated . The FUNCHIP project addresses these two aspects , the actuator, and thermal managment ( packaging and the switching time will not be addressed in this project). For a given voltage , the electrostatic actuators parallel plate MEMS see their strength increase progressively as the gap separation between the plates decreases. Thus, small separation gaps permit reaching large forces. This increase is limited byelectrical breakdown phenomena that not well understood today because the physics of submicron breakdown ( Paschen effect , for example) has been little studied . Beyond the effects of the ambient gas , the nature of the metals used for the electrodes, their roughness , and layout affects their behavior. The FUNCHIP project will investigate systematically the properties of metals commonly used in microelectronics and test the breakdown strength of several simple test vehicles. Leakage current measurements will also look more finely into the physical phenomena involved in order to determine the nature of these currents. We will be able to determine gaps heights that ensure a reliable and optimal operation of these actuators. To optimize the thermal behavior of the relay , substrate transfer techniques will be used. Using thin substrates will directly improve thermal performance of micro- switches. However, these thin substrates will reduce the cross section of access lines to micro- switches, and therefore increase losses, and the mismatch between the switch structure and input lines. Trhough electromagnetic and thermal simulations simulations, we will find an optimal compromise to achieve a component with good thermal characteristics and low losses. The last part of the project will be devoted to design and implementation of a micro switch following the previous results. Specifically, we will build a micro switch with a powerful electrostatic actuator, with a gap as small as possible, on an optimized substrate. The micro -switch will be tested at high microwave powers to targeted levels from thermal simulations. With available imaging techniques to LAAS , we can validate our simulations and have effective design rules for power applications adapted to defense applications .

The overall vision of the project is to develop comprehensive knowledge and an innovative methodology in the areas of energy autonomous wireless systems from a global system perspective, enabling self-powered, battery-free wireless sensing nodes to meet a wide range of structural health monitoring (SHM) applications. The research is multi-disciplinary, and designed to enable the emergence of innovative energy technologies suitable for transfer from laboratories to industries. The research vision builds on the project partners’ complementary skills and strengths in the area of 'towards zero-power ICT' with the potential to lead to multiple scientific and technical breakthroughs.. The first breakthrough is to make use of the SHM sensing device itself to implement a single multifunctional device providing both structural health data and electrical energy harvested from mechanical vibrations. Another breakthrough will be to store the harvested energy in a fully integrated smart storage device, which adapts its storage capacity, according to the available energy in the environment and to the power consumption of the load. This adaptability will provide a constantly optimized matching between storage device and energy harvester to foster energy transfer. The energy storage itself will be a micro-ultracapacitor, so will have the desirable features of high specific energy, short time response, long lifetime and safe operation. This micro-ultracapacitor will be implemented in a silicon compatible technology so as to facilitate co-integration with other functions. A final innovation will be the co-location of the different devices (harvesting, sensing, storage, processing, data transmission) on the same flexible substrate, in order to enable conformal attachment of the device, a characteristic highly desirable in a SHM context where the surfaces to be monitored are seldom planar. Additionally, by this means the issue of the anisotropy of vibration harvesters is settled, the harvester being, by nature, properly oriented. More globally, the project aims at producing a device in which co-integration, co-location of functions, versatility of applications and energy autonomy are pushed to a maximum.