Meander Design Research Articles

Theoretical and Experimental Studies of Flip-Chip Assembled High-$Q$ Suspended MEMS Inductors

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper reports the theoretical and experimental studies of high-<formula> <tex>$Q$</tex></formula> suspended microinductors produced by flip-chip assembly for multigigahertz RF integrated-circuit applications. The effects of device and substrate parameters on the <formula formulatype="inline"><tex>$Q$</tex> </formula> factor of the inductor devices are studied by numerical simulation using Ansoft's High Frequency Structure Simulator electromagnetic field simulation package. Suspended inductor devices are realized using a flip-chip assembly method in which the inductor structures with the supporting pillars are fabricated on a low-cost polyimide thin-film carrier and then assembled onto a low resistivity (3–4 <formula formulatype="inline"><tex>$\ \Omega\,\cdot\,$</tex></formula>cm) silicon substrate by flip-chip bonding. Individual and 2<formula formulatype="inline"> <tex>$\,\times\,$</tex></formula>2 arrays of meander and spiral inductor designs have been successfully fabricated with air gap heights ranging from 15 to 31 <formula formulatype="inline"><tex>$\mu$</tex></formula>m. Maximum <formula> <tex>$Q$</tex></formula> factors of <formula formulatype="inline"><tex>${\sim}$</tex> </formula>15 and <formula formulatype="inline"><tex>${\sim}$</tex></formula>13 at <formula formulatype="inline"><tex>${\sim}$</tex></formula>1 GHz have been achieved for meander and spiral suspended inductor devices before pad deembedding. It is shown that the optimal air gap between the inductor and substrate surface is <formula formulatype="inline"><tex>${\sim}{\hbox{15}}\ \mu$</tex></formula>m beyond which no further enhancement in the <formula formulatype="inline"> <tex>$Q$</tex></formula> factor can be obtained for devices on low-resistivity substrates. The experimental results are in excellent agreement with that of theoretical simulation. The inductor assembly method requires minimal chip/wafer processing for integration of high-<formula><tex>$Q$</tex></formula> inductors. </para>

On-chip micro-electromagnets for magnetic-based bio-molecules separation

This paper reports a comprehensive theoretical, finite element and measurement analysis of different designs of planar micro-electromagnets for bio-molecular manipulation. The magnetic field due to current flowing in complex shapes of current-carrying conductors have been calculated analytically, simulated using finite-element analysis (FEA), and measured using the superconducting quantum interference device technique (SQUID). A comparison of the theoretical and measured magnetic field strength and patterns is presented. The planar electromagnets have been fabricated using patterned Al 2μm thick. The aim of the study is to explore and optimize the geometrical and structural parameters of planar electromagnets that give rise to the highest magnetic fields and forces for magnetic micro-beads manipulation. Magnetic beads are often used in biochemical assays for separation of bio-molecules. Typical beads are 0.2–10μm in diameter and have superparamagnetic properties. Increasing the intensity of the magnetic field generated by a coil by injection a larger current is not the most suitable solution as the maximum current is limited by Joule heating. Consequently, in order to maximize the field for a given current, one should optimize the geometry of the coil, as this is an extremely significant factor in determining the magnetic field intensity in 2D planar designs. The theoretical and measured results of this work show that the meander micro-electromagnet with mesh-shaped winding profile produces the strongest magnetic field (about 2.7μT for a current intensity of 6mA) compared with other meander designs, such as the serpentine and rosette-shaped ones. The magnetic fields of these three types of meander-shaped micro-electromagnets were compared theoretically with that produced by a spiral micro-electromagnet whose technological realization is more complicated and costly due to the fact that it requires an additional insulation layer with a contact window and a second patterned metal layer as a via. Nevertheless, the spiral design produces a much stronger magnetic field up to five times larger than that of the mesh-shaped micro-electromagnet for the same current and electromagnet area. The measured results strongly agree with these conclusions resulted from the theoretical analysis. The results presented in this paper provide a solid and useful basis for the design of a micro-fluidic bio-molecule separation and detection system using magnetic fields and magnetic beads.

サキザバード出土の彩文土器について

Some scholars such as S. M. Kaplan, H. H. Von den Osten and R. Heine-Geldern already pointed out the possible existence of the relation between the so-called “black” pottery of prehistoric China and the similar pottery of prehistoric Iran, and even suggested the origin of the former pottery to the latter. These arguments are very attractive, but as S. Masuda has remarked, there are yet too scarce of positive proofs to demonstrate these inferences, though the existence of tripods in Li and Ho shapes which are generally supposed as rather peculiar in prehistoric China among the so-called Amlash pottery, seems to affirm at least the indirect relation between the “black” pottery cultures of prehistoric Iran and China.Here I treat these pottery cultures of East and West not through the monochrome, but through polychrome pottery.Since about 1960, there have appeared many polychrome and monochrome pottery in Tehran curios market, which they refered to the finds from Sakizabad not far from Kazvin southwardly.The painted pottery of Sakizabad show not so many kinds of shape: pots with a short neck, a round body and a wide mouth, pots like cups with a small base and a handle at one side near the mouth, bowls with a carinated body and a small base, shallow bowls and dishes are most commonly seen (Pls. I-IV, VI-XIII). The pots, shallow bowls and dishes are often supported by three legs (figs. I-4, V-4), and the pots have sometimes on both-sides of their shoulders a pair of lugs with a small hole for a string to pass through in order to suspend the pottery (Pls. II, III).The Sakizabad painted pottery seem to show the fabrication not by the method of potter's wheel, but by the ring-method or direct hand-make, because of their uneven surfaces and considerably irregular shapes. The temperature of their firing must have been rather low, the quality of the pottery being soft, porous and rough. The surface of the pottery seems in the majority of cases to be covered with a thin coating of “slip” in whitish or reddish colour.Decorative paintings on slip are applied mostly on the outer surface of the pottery, but also on the inside surface in the case of shallow bowls and dishes. According to the construction and colour of the painted designs, the Sakizabad painted pottery are roughly divided into two groups. The first group is characterized by its bold stroke of painting on the whitish slip surface of comparatively thicker wall of the pottery (Pls. I-V figs. II-1, III-3, IV-2, V). The common designs of the first group are: triangle, rhomb, meander, zig-zag lines, twined wavy lines, all arranged in horizontal bands, which divide the whole or the larger parts of the outer surface of the pottery, and swastika-like geometric designs and asterisk designs are also seen on the inside surface of the pottery (figs. V1, 4).The common colours of their paintings are: black, red and gray, tinged sometimes with purple, brown or yellow. Three or more colours are applied so often in this group of the Sakizabad painted pottery.The second group is characterized with the designs drawn by fine stroke in multiple lines on whitish or reddish slip surface of the comparatively thin wall of the pottery. The common designs of this group are: so-called staircase design, checker, rhomb, meander and meander-like geometric designs, zig-zag lines, wavy lines and x-shaped lines, all arranged in horizontal bands which cover the larger part of the outer surface of the pottery, and fantastic, highly stylized zoomorphic designs and asterisk designs together with rhombs and zig-zag lines freely drawn on the inside surface of the pottery (Pls. XIV right, XV). The common colours of their paintings are: black, red and gray tinged with purple or brown. In this group of the Sakizabad painted pottery, black paintings are seen both on reddish and whitish slip, while red paintings are only on whitish slip as general rule.The