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In this paper, the development and characterization of thermopneumatic peristaltic micropumps are presented. Micropumps with three different designs are fabricated using soft lithography techniques. The equivalent circuit models of a thermopneumatic actuation cell are formulated. The analytical solutions for predicting the device transient behavior are also derived. The dynamical responses of the diaphragms are measured using an interferometer, and are in good agreement with the modeled results. Tiny drive circuits, which require only 5 V, are implemented for driving the pumps. The dimension of an integrated 3-chamber micropump system, which consists of a pump and a drive circuit, is 16 mm × 18 mm × 5.5 mm. The optimal operating conditions, such as actuation sequences, operating frequencies and duty ratios, are obtained. The maximum flow rate occurs at a driving frequency of 1.5 Hz with a duty ratio of 40% using a three-phase actuation sequence. A simplified pseudo thermo-fluid-structure-interaction (pT-FSI) model is also proposed to estimate the pumping characteristic. The model gives reasonable results under low operation frequency. Under zero backpressure, the maximum flow rates for the 3, 5 and 7-chamber devices are very close, whereas the devices with larger numbers of pumping chambers exhibit better pumping performance under higher backpressure.

This work presents the development of a novel micromachined 2x2 optical switch monolithically integrated with variable optical attenuators. The proposed device can be easily realized by a standard manufacturing process with single photo mask. The key to realizing this device by such a simple approach is the employment the split-cross-bar (SCB) configuration. With this configuration, the fabrication challenges and layout constraints for accommodating all the sub-components of this dual-function device can be completely eliminated. The monolithically-integrated system has four movable mirrors, two bi-stable mechanisms and six actuators. The switching of optical signals is achieved by moving the mirrors attached on the bi-stable mechanisms using four of the actuators. The attenuation of optical power is carried out by moving the mirrors using the other two actuators and the bi-stable mechanisms. Also, only simple in-plane motions are needed for these sub-components to achieve all the functionalities. In addition, the adaption of bi-stable mechanisms can reduce the power consumption and simplify the actuation scheme. The measured insertion losses for both channels are about 1.0~1.1 dB, and the cross-talk is less than -60 dB. The attenuation range is about 30 dB for a maximum applied voltage of 20 V. Also, the measured switching time is less than 4 ms.

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