M.Sc Thesis

M.Sc StudentMahameed Rashed
SubjectA Novel Thermoelastic Actuation Scheme for Micro Resonators
DepartmentDepartment of Mechanical Engineering
Supervisor PROF. David Elata


A novel actuation scheme for dynamic vibration of deformable microstructures is presented. This actuation scheme makes use of the thermoelastic response of the structure material.  In existing thermoelastic actuators, the driving forces are induced by a change in the structure temperature. In contrast, the novel thermoelastic actuation scheme exploits local gradients of the temperature to induce the driving forces. As a result, activation and termination of the driving forces in the novel scheme are far more rapid.  The new scheme is employed to design a cantilever beam microresonator with high frequency and large deflection amplitudes.

To demonstrate the novel actuation scheme and investigate its performance, the dynamic response of a microresonator beam is simulated.  The simulation is performed with the ANSYSTM finite element code using coupled-field harmonic analysis.  The maximal deflection at the free edge of the beam is computed assuming a damping ratio of  z=0.01 and neglecting convection.

For the specific geometric dimensions of: beam length L=800[mm], beam height h=10 [mm], a maximal deflection amplitude of 22 [mm] was achieved at the free end of the beam.  This maximal amplitude is of the order of the beam height.

For this thermoelastic resonator, the thermal time scale across the beam height is th»1 [ms], which suggests that it may be driven in frequencies of up to f » 0.5 [MHz].

The novel thermoelastic actuation scheme for microresonators presented in this work enables higher frequencies than can be achieved by using existing thermoelastic actuation schemes on structures of comparable dimensions.  Furthermore, the specific example analyzed here demonstrates that large deflection amplitudes may be achieved.