Mechanical quality factor (Q-factor) is essential to detect-limitation of a resonant based mass sensor because it
determines signal to noise ratio. This paper studies the effects of different energy dissipation mechanisms, including air
damping, support loss and thermoelastic damping (TED), on Q-factor of a microcantilever under atmospheric pressure
conditions. The contribution of each mechanism was analyzed at various cantilever geometry. And the precondition to
Z.Hao's model, which describes the support loss effect by elastic wave theory, was discussed. It was found that in 5 μm-thick
silicon cantilevers, air damping was the predominant reason to energy dissipation when cantilever length was larger
than 140 μm. The support loss and TED became noteworthy at shorter cantilevers when cantilever length to thickness
ratio (L/t) was less than 20. Q-factor of a microcantilever thus can be improved by increasing the cantilever thickness to
suppress air damping, but not infinitely because the support loss became comparable to air damping when cantilever
thickness was increased. Moreover, it was found that the Q-factor of a multi-layered microcantilever was degraded
markedly with the increase of layer numbers.
We proposed one novel MEMS-based thermometer with low power-consumption for animal/human health-monitoring
network application. The novel MEMS-based thermometer was consisted of triple-beam bimorph arrays so that it could
work in a continuous temperature range. Neither continuous electric supply nor A/D converter interface is required by
the novel thermometer owing to the well-known deflection of bimaterials cantilever upon temperature changes. The
triple-beam structure also facilitated the novel thermometer with excellent fabrication feasibility by conventional
microfabrication technology. The parameters of the triple-beam bimorph arrays were determined by finite element
analysis with ANSYS program. Low stress Au and Mo metal films were used as top and bottom layer, respectively.
The deflection of the triple-beam bimorphs were measured on a home-made heating stage by a confocal scanning laser
microscopy. The novel bimorphs had temperature responses similar to traditional single-beam bimorphs. Initial bend of
the prepared triple-beam bimorphs were dominantly determined by their side beams. The sensitivity of the novel
thermometer was as high as 0.1°C. Experimental results showed that the novel thermometer is attractive for network
sensing applications where the power capacity is limited.