P. Lerch

Piezoelectric cantilever beams actuated by PZT sol-gel thin film

The mechanical response of piezoelectric cantilever beams actuated by sol-gel- derived lead zirconium titanate (PZT) thin film is reported. Small multilayered beams are used to analyse the converse piezoelectric effect and to measure the mechanical deflection of the beams with a standard interferometry method. Interferometric displacement measurements, electrical measurements and finite- element simulations are reported to determine the piezoelectric coefficient d(31) of the PZT thin film.

Improved design for fast modulating IR sources

The simulation and characterization of a low-cost IR source are described. The IR emission is obtained from heated thin film resistors which are either self-suspended or deposited on a membrane. The simulation, performed with a finite difference method, shows that a reasonably good modulation can be obtained at 50 Hz and higher. Such specifications meet the requirements of various IR gas sensors such as photoacoustic sensors.

Modeling and Simulation of Electromechanical Transducers in Microsystems Using an Analogue Hardware Description Language

The analytical modeling and simulation of conservative electrostatic, electromagnetic and electrodynamic transducers found in microsystems using a non-linear lumped-parameter approach is presented in this paper. A comparison is made between this approach and the linearized equivalent circuit method. All models of transducers are written in HDL-A/sup TM/, a proprietary analogue hardware description language (HDL). System-level simulation is performed in the SPICE simulator using behavioral models of the transducers. Finally, a parameter extraction and HDL model generation tool for devices is presented.

Numerical simulations of planar electrostatic wobble motors

We present a numerical study of the electrostatic wobble motor. Both finite-element calculations and analytical approaches are used to calculate the torque exerted by the electrodes. Both methods give very similar results, validating an analytical approach. We also study the dynamic behaviour of this type of motor. We show how to optimize the torque by optimally adapting mechanical and electrical parameters.

Mode coupling aspects in a vibrating gyroscope

In this paper a new method for gyroscopic sensitivity evaluation of a vibrating angular rate sensor is presented. This method is used to evaluate the angular rate sensitivity of a four-beam-bridge gyroscope realized at IMT Neuchatel [ii. The frequency splitting between the excitation and the detection mode due to mechanical mode coupling is investigated. A design variant with optimized dimensions is proposed in order to reduce frequency splitting and increase the angular rate sensitivity

Piezoelectric Cantilever Beams Actuated By PZT Sol-gel Thin Film

Micromachined silicon cantilever beams actuated by the converse piezoelectric effect are of great interest for actuator applications [1], and for the characterization of piezoelectric thin films [2]. In this work a study of the mechanical response of piezoelectrically operated heterogeneous bimorph structures is given and compared with finite elements simulations. Determination of the piezoelectric parameter d/sub 31/ using interferometric displacement measurements, electrical impedance measurements, and finite element calculation will be discussed.

Design and modelling for a thermal flow sensor

Design and modelling have been made for a new type of integrated flow sensor for implementation in a CMOS compatible technology. The sensor is designed for both gas and fluid flow sensing in applications with transient velocity and temperature profiles. This appear also in microfluidics where there is a pulsating flow when drive is made with micropumps. The sensor is analysed for fluid flow and heat transfer. Modelling and optimisation of the sensor give results for the necessary geometrical parameters and materials of the sensor for maximising the sensibility in applications with a known fluid and in a given domain of fluid velocities and temperatures.

From simple devices to promising microsystem applications

We discuss both limitations and potentialities of micromechanical devices based on simple microtechnologies. We briefly review flow sensors and their applications. Underlying technologies and prospective applications are discussed.

Integrated flow sensor for fluids with dynamic velocity, temperature and conductivity profiles

A new type of integrated thermal flow sensor containing two symmetrical measuring channels is presented. The structure permit optimisation of flow sensing in applications with transient velocity, temperature or conductivity profiles in the fluid and has improved sensitivities for small temperatures differences above ambient, necessary for medical applications. Analysis is made for fluid flow and heat transfer using analytical and FEA technics. Technological implementation optimises the compensation of the internal stresses in the suspended structures and passivation of the sensor structure for work in aggressive media. Electronic interfaces for processing are derived for development of a fully integrated variant of the sensor.

Modelling and optimisation for an electrostatic actuation of a valveless micropump using a silicon buckled membrane

An electrostatic actuator for micropumps driving has been designed. Modelling and optimisation of the actuator have been made for obtaining small driving voltages for harmonic oscillations in the kHz frequency range with submicrometer amplitudes and for developing improved external forces.