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This paper describes the design, simulation and fabrication of a micro conveyer system (MCS) with straight displacement of micro containers based on ratchet mechanisms and electrostatic comb-drive actuators. This MCS consists of linear comb actuators, micro containers and ratchet racks. The micro containers can be moved with different velocities by comb-drive actuators through ratchet teeth. In this study, a SOI wafer with a device layer of 30 µm and a buried SiO2 layer of 4 µm is used. Each module of the MCS has dimensions of 6 × 6 mm2, is fabricated by using only one mask, ICP-RIE and vapor HF etching techniques, and can be assembled to create more complex conveyance systems for different applications, such as in bio-chemical analysis or a micro total analysis system (µ-TAS) to transport and classify small samples. In our experiments, the movement of the micro container has been tested with a driving frequency ranging from 5 Hz to 40 Hz. The velocity of the container was proportional to the frequency and matched very well with theoretical calculation.

This paper describes a Si micro transportation system (MTS) to drive micro containers in straight movement based on a ratchet mechanism and electrostatic comb-drive actuators. This MTS consists of linear comb actuators, micro containers and ratchet racks. The lateral movements of ratchet racks push the micro containers which move straight in a perpendicular direction with different velocities. The MTS was fabricated from a SOI wafer by using only one mask. In our experiments, the movement of the micro container has been tested with driving frequency ranges from 1 Hz to 20 Hz. The velocity of the micro container was proportional to the driving frequency, and it matched well with the theoretical calculation.

In this paper, we propose a fabrication and characterization of silicon mold for PMMA hot embossing process. Silicon molds were fabricated from silicon wafer with thickness of 500µm. First, DRIE technique was performed after optimized etching time and deposition (passivation) time to obtain a depth of 30µm with positive tapered sidewall of 1°. This is very important for de-molding process while hot embossing. Second, in order to reduce scalloping steps on the sidewall after DRIE, silicon molds were soaked in the TMAH solution 20% at 80°C for 10 minutes without magnetic stirrer. Third, to further reduce the friction coefficient between sidewall surface and PMMA substrate while de-molding, the post-passivation technique was applied to create a thin layer of Teflon-like material on the surface of the sidewall of silicon mold. These smooth silicon molds were used to emboss several models of PMMA patterns and comb-drive actuators, as well as applications in Micro Conveyer System. The PMMA patterns obtained after hot embossing process had very sharp edge and aspect ratio of 15 with minimum feature sized of 2µm.

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