This paper presents a compliant monolithic multistable actuator which is able to switch its moving part between several stable positions linearly in one dimensional direction. The number of stable positions can be increased by extending the range of displacement of the moving part. The transition in each step of displacement is made to the nearest stable position in the direction of motion. Upward and downward steps are made by a specific sequence of moving, using a bistable module, opening and closing two internal clamps which are actuated by U-shaped electrothermal actuator using three subsystems. The principle and the design of each subsystem in the discrete acruator, fabrication process and experimental results are presented. The fabricated prototypes of the discrete actuator showed a proper functioning. The mean achieved displacement is 120.67±0.08 µm over 12 upward steps with a mean step of 10.06 µm, which is very close to the designed performance.

International audienceIn this work we report the fabrication of N channel transistors based on IF(CN2)2 meta molecule. The effect of IF(CN2)2 meta evaporation parameters on corresponding TFTs performances, is evaluated and highlighted here. Since the effect of deposition conditions for this molecule type has not been reported yet, here we report an improvement about 20 times of field effect mobility when deposited at substrate temperature of 80 °C and deposition rate of 0.7 Å/s, and then annealed at low temperature. Reached mobility of 2.2 × 10−3 cm2/V·s, is comparable to reported μFE of single crystal indenofluorene TFTs. The optimum mobility in these evaporation conditions was explained by the best compromise between the grain size and packing density of films. Fabricated IF(CN2)2 meta based devices are combined to 6,13-Bis(triisopropylsilylethynyl)pentacene devices and then integrated into a CMOS inverter logic circuit. The inverter's VTC shows large output voltage swing. Electrical stability of the performed inverter was also evaluated and the inverter shows a correct electrical stability, after 3 h of non-stop operation and the peak to peak magnitude corresponding to VOUT decreases only by 2.6%

Current digital microrobots are mainly composed of bistable modules and flexible structures. Unlike conventional microrobots, they are based on mechanical stability instead of complex control strategies in order to reach precise and repeatable discrete positioning. By design, their number of stable positions depends on the number of bistable modules. As a consequence, increasing the robot workspace requires using several modules. In this case, the robot size increases and its miniaturization becomes complex and non-intuitive. To address this issue, a multistable module has been developed to reach several stable positions. In this paper, a new generation of digital microrobots is proposed. Based on two multistable modules and flexible structures, the new microrobot can reach a large workspace while having a small footprint. Concretely, the robot size decreases by 26% while the number of stable positions increases by 950% in comparison with the first generation of the digital microrobot. A prototype is designed, fabricated and characterized experimentally. Preliminary results show a good agreement between the expected and the achieved workspace. The robot achieves 169 stable positions with a discrete step of 4.125 µm and a resolution of 150 nm. With these capabilities, the robot paves the way for promising perspectives and applications, in particular precise micro-manipulation in confined environment such as a Scanning Electron Microscope.

This paper focuses on the dynamic characterization of an electrothermal actuator devoted to discrete MEMS positioning. Based on U-shape structure, such actuator has been employed in several MEMS applications where fine and repeatable positioning is required. The studied electrothermal actuator here is microfabricated on a doped SOI substrate and its dynamic response, during heating and cooling cycles, is recorded using precise and high-speed camera. To explain its dynamic behavior, FEM simulations, using Comsol multiphysics software facility, are carried out. The result of this numerical analysis shows a strong relationship between the temperature distribution and the displacement provided by the actuator. Finally, the influence of the dynamic behavior on the control of the actuator is discussed using experimental characterizations of its displacements under several voltage pulses with different frequencies.

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