RESUMEN
This Note presents a new asymmetric flexure design, the double parallelogram-tilted-beam double parallelogram (DP-TDP) flexure, that enables two times higher stroke in electrostatic comb-drive actuators, compared to the traditional symmetrically paired double parallelogram (DP-DP) flexure, while maintaining the same device footprint. Because of its unique kinematic configuration, the DP-TDP flexure provides an improved stiffness ratio between the bearing and actuation directions, thus delaying the on-set of sideways instability. Experimental testing of micro-fabricated comb-drive actuators with flexure beam length 1 mm and comb gap 5 µm demonstrates a stroke of 149 µm (at 86 V) for the proposed DP-TDP flexure, in comparison to 75 µm (at 45 V) for the traditional DP-DP flexure.
RESUMEN
Influences of different vibration modes of microdiaphragm resonating biosensors on their detecting capability are investigated in this paper. In order to study the mass sensing capability of the sensor, gold layers with different thicknesses are deposited on the sensor's surface. The frequency shift due to this mass deposition in different frequency modes is measured. An increase in the sensitivity and the quality factor (Q-factor) is found with the increase in the vibration mode number of the sensor. The experimental results demonstrate that the mass sensitivity and quality factor of the device are 4.08 Hz/ng and 241.80 at the ninth mode. These are 2.76 and 10.26 times higher than the mass sensitivity and the Q-factor of the device at the first mode. The observations lead to this conclusion that the sensitivity of microdiaphragm resonating biosensors can be increased by working in higher modes without changing their physical parameters.