On-Chip Tests for the Characterization of the Mechanical Strength of Polysilicon †

Microelectromechanical systems (MEMS) are nowadays widespread in the sensor market, with several different applications. New production techniques and ever smaller device geometries require a continuous investigation of potential failure mechanisms in such devices. This work presents an experimental on-chip setup to assess the geometry- and material-dependent strength of stoppers adopted to limit the deformation of movable parts, using an electrostatically actuated device. A series of comb-finger and parallel plate capacitors are used to provide a rather large stroke to a shuttle, connected to the anchors through flexible springs. Upon application of a varying voltage, failure of stoppers of variable size is observed and confirmed by post-mortem DC–V curves. The results of the experimental campaign are collected to infer the stochastic property of the strength of polycrystalline, columnar silicon films

Reduced order modelling and experimental validation of a MEMS gyroscope test-structure exhibiting 1:2 internal resonance

Micro-Electro-Mechanical Systems revolutionized the consumer market for their small dimensions, high performances and low costs. In recent years, the evolution of the Internet of Things is posing new challenges to MEMS designers that have to deal with complex multiphysics systems experiencing highly nonlinear dynamic responses. To be able to simulate a priori and in real-time the behavior of such systems it is thus becoming mandatory to understand the sources of nonlinearities and avoid them when harmful or exploit them for the design of innovative devices. In this work, we present the first numerical tool able to estimate a priori and in real-time the complex nonlinear responses of MEMS devices without resorting to simplified theories. Moreover, the proposed tool predicts different working conditions without the need of ad-hoc calibration procedures. It consists in a nonlinear Model Order Reduction Technique based on the Implicit Static Condensation that allows to condense the high fidelity FEM models into few degrees of freedom, thus greatly speeding-up the solution phase and improving the design process of MEMS devices. In particular, the 1:2 internal resonance experienced in a MEMS gyroscope test-structure fabricated with a commercial process is numerically investigated and an excellent agreement with experiments is found

Investigation of Gyroscopes Mechanical and Electronic Phase Drift with 2 μrad/√Hz Resolution and 12 μrad/K Accuracy

The work demonstrates a setup for the accurate calibration of the relative phase drift between sense modulated output and drive demodulation reference in MEMS gyroscopes. The system enables to operate the sensor inside a climatic chamber, with all the electronics outside, reaching 2 μrad/√Hz short-term resolution in relative phase measurements. After a one-time calibration of parasitic electrical couplings, the setup enables to measure the phase drift in temperature with a sub-5-μrad long-term stability. On average, measurements over four samples, swept vs temperature in 18 different operating conditions, deviate from modeling by 12 μrad/K only

Direct Phase Measurement and Compensation to Enhance MEMS Gyroscopes ZRO Stability

This research introduces a closed-loop method to improve the zero-rate output (ZRO) stability of amplitude-modulated (AM) capacitive MEMS gyroscopes, even in absence of quadrature compensation electrodes. The method relies on the direct measurement and closed-loop compensation of the variation of the relative phase between the quadrature output, modulated by the drive carrier frequency, and the demodulation reference. The closed loop includes a phase meter, whose output regulates the phase of the lock-in amplifier inside the sense-mode, open-loop, demodulation chain. The proposed technique, tested on the pitch axis of a consumer-grade commercial monolithic 3-axis gyroscope, brings up to 300-fold stability improvements over temperature transients, without affecting noise and scale-factor performance. Stability limits depend on the phase meter resolution and on the lock-in granularity in regulating the phase. Overall, a mdps/K stability is obtained with a one-time calibration at ambient temperature and no post-acquisition processing. [2021-0049

Chipping and wearing in MEMS inertial sensors: Effects on stability and predictive analysis through test structures

Impacts between fixed and moving parts in capacitive MEMS inertial sensors can generate debris and wear that undermine the device stability. This work investigates the effects of impacts and friction between rotors and stoppers through dedicated test structures. After modeling the scenario, considering the impact kinetic energy and the tensile/ compressive nominal strength of silicon, different stopper topologies and collision angles are studied. Results show how impact kinetic energies, up to 40 nJ (velocities in the 1-3 m/s range for typical inertial sensor masses), correlate with silicon rupture and provide first guidelines for robust sensors design

Mems gyroscope with improved rejection of a quadrature error

A MEMS gyroscope is equipped with: at least a first mobile mass suspended from the top of a substrate by means of elastic suspension elements coupled to anchor points rigidly fixed to the substrate, in such a manner as to be actuated in an actuating movement along a first axis of a horizontal plane and to carry out a measurement movement along a vertical axis, transverse to the horizontal plane, in response to a first angular velocity acting about a second axis of the horizontal plane, transverse to the first axis. The elastic suspension elements are configured in such a manner as to internally compensate unwanted displacements out of the horizontal plane along the vertical axis originating from the actuating movement, such that the mobile mass remains in the horizontal plane during the actuating movement

An Aesthetics of Engagement. Intercultural Dialogue and Performative Practices in the Territory of Milan

This contribution illustrates some results of the research Migrations | Mediations. Arts and communication as resources for intercultural dialogue, conducted at the Department of Communication and Performing Arts of the Universit\ue0 Cattolica del Sacro Cuore (Milan) since 2017, currently in its final phase. The project, which was funded by the Universit\ue0 Cattolica as a \u201cUniversity Interest Project\u201d, gave birth to a website that is still active1, various publications, a number of seminars, a national conference in January 2019 and an international conference scheduled for the Winter 2020-2021