Tunable MEMS cantilever resonators electrothermally actuated and piezoelectrically sensed

• Electrically tunable MEMS cantilever resonators are presented.
• Electrothermal actuator and piezoelectric sensor are integrated on top of cantilever.
• Two-port measurements of transmission frequency response in air are performed.
• Device with shorter beam length shows a wider tuning range.
• Origin of resonant frequency change induced by tuning DC voltage is investigated.

This paper reports on microelectromechanical (MEMS) cantilever resonant devices that are actuated electrothermally and sensed piezoelectrically, and have voltage tunable resonant frequencies. The devices have been designed as a two-port vertical-mode cantilever resonator. The single-clamped beam (cantilever) resonators have been fabricated in silicon carbide with top platinum electrothermal actuator (input port) and lead zirconium titanate piezoelectric sensor (output port). The performance of the devices has been demonstrated with two-port measurements of the transmission frequency response in atmospheric conditions. The measurements have shown that the devices with a beam length of 200 and 250 μm resonate in the frequency range 373–523 kHz with Q factor in air up to 455. By applying DC bias voltage between 6 and 11 V, a frequency tuning range of about 1300 ppm has been achieved, with the tuning range being wider for the shorter cantilever. Simulated results for different cantilever lengths show that higher temperature and stress are induced in the shorter cantilever, indicating that the resonant frequency change observed as a function of tuning DC voltage is dominated by the stress effect rather than geometric effect.

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