A surface-finishing method for three-dimensional microchannel structures is proposed. The method utilizes magnetorheological fluid mixed with abrasives as a polishing tool. The influences of the process parameters on the material removal were investigated, and the surface topographies before and after finishing were compared. When a microchannel was finished by proposed method, the roughness of bottom and side surfaces of the silicon channel was reduced by a factor of 5–10, and the pressure drop of a gas flow through the single microchannel was lowered to 26.7% of the pressure drop in an unfinished microchannel. The experimental results demonstrated that the proposed method was effective in finishing of microstructures.

Core fabrication is one of the key technologies of glass moulding process used in micro optical component manufacturing. However, when the cavity size is very small and an array-type cavity is needed, a conventional diamond turning process cannot be employed. In this study, a novel core fabrication method that can be used for glass micro optical components has been developed. First, microlens array (with individual lens diameters of 36–300 µm) mould masters were produced with silicon using a photoresist reflow and a reactive ion etching process. Then, the shape of the silicon lens masters was transferred to tungsten carbide cores using a powder pressure forming and a sintering process. To further improve the surface qualities, magnetic abrasive finishing was carried out. The details of the fabrication process are presented in this paper. The characteristics of the proposed method, such as the shrinkage in the sintering process and the effects of grain size of the tungsten carbide powder and abrasive finishing process on the surface qualities, were also discussed.

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SUMMARYBuildings are continually subject to dynamic loads, such as wind load, seismic ground motion, and even the load from internal utility machines. The recent trend of constructing more exible high-rise buildings underscores the importance of including viscoelastic dampers in building designs. Viscoelastic dampers are used to control the dynamic response of a building. If the seismic design is based only on the linear response spectrum, considerable error may occur when calculating the seismic response of a building; rubber viscoelastic dampers show non-linear hysteretic damping that is quite di erent from viscous damping.This study generated a non-linear response spectrum using a non-linear oscillator model to simulate a building with viscoelastic dampers installed. The parameters used in the non-linear damper model were obtained experimentally from dynamic loading tests. The results show that viscoelastic dampers e ectively reduce the seismic displacement response of a structure, but transmit more seismic force to the structure, which essentially increases its seismic acceleration response.

In this paper, a novel polishing method using magnetorheological (MR) fluid is presented in order to improve conductor‐surface roughness and achieve high‐frequency performance of the electroplated three‐dimensional (3D) CPW, where the MR fluid is utilized to efficiently polish uneven and imperfect conductor surfaces resulting from the widely used MEMS process. For the purpose of comparison, two 50Ω CPW lines on glass substrate are fabricated in order to validate the performance of the proposed polishing scheme. From the measurement, the polished CPW lines using the MR fluid show much lower attenuation constants up to a maximum of 0.3–0.54 dB/cm than unpolished CPW lines, according to the geometries used. Thus, it is clear that the proposed MR fluid‐based polishing scheme is very effective when used to smooth 3D high‐frequency structures and can dramatically improve conductor‐loss characteristics. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 405–407, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20318