MMC Activities

Research on the Application of Sprout MultiDisciplinary Technologies in MicromachineTechnology in Fiscal 2000
Since 1992, the Micromachine Center has taken up a diverse range of technology seeds as themes for joint research by academic, governmental, andindustrial sectors, all with the aim of reinforcing basic technologies by searching for the technology seeds, especially in the scientific and technologicalfields, necessary to build various micro systems. In fiscal 2000, research has been conducted along five themes; these five themes are summarized below.

Study on Wearable Energy Sources
Masayoshi EsashiProfessor,
New Industry Creation Hatchery Center, Tohoku University
turbine generators, and the like are being studied as energy sources.
Since automatic generating and charging systems free the userfrom secondary battery charging and fuel refilling, these systems are
suitable for such applications as portable health care terminals,
which require that a minimum of mental and physical burden beplaced on the user, and animal tracking devices or polar
environment observing equipment, on which maintenance is notpractical. Technologies for automatic generating systems used inwristwatches and noncontact electrical supply systems used inwireless ID tags are employed as base technologies of these
automatic generating and charging systems.
This paper discusses examples of wearable and compact energy
sources, including fuel cells, fuel reformers, automatic mechanicalgenerators, thermoelectric generators, noncontact electrical supplysystems, double-layer capacitors, thin film batteries, and heatengines. The paper also clarifies the current state and future ofwearable energy sources used in place of primary and secondary
batteries and their relationship with micromachine technologies.

Wearable energy sources are compact energy sources that canbe mounted in humans, animals, robots, and the like. Presently,primary and secondary batteries are widely used as wearable energy
sources. In the present study, we investigated the feasibility of new
wearable energy sources with functions not found in primary andsecondary batteries.
By efficiently supplying electricity from chemical fuels having anenergy density 1-2 digits greater than batteries, wearable energy
sources using chemical fuels are advantageous in that they havepotential for achieving a high energy density and high output
density. Moreover, unlike secondary batteries that must berecharged, the new wearable energy sources can be continuously
used simply by refilling them with fuel. By combining a reusable
compact generator with an easily recyclable fuel cartridge, this typeof energy source is more environmentally friendly than primary andsecondary batteries that accompany such problems as organic
matter and waste. Hence, these wearable energy sources support a
recycling society. Currently, micro-fuel cells, silicon micro-gas

A Study on Applied Technologies for Microchannels
Takayoshi Inoue
Professor,Department of Mechanical Sciences and Engineering, Tokyo Institute of Technology
generated in these micro devices. When considering that the thermalresistance R = DT/q, defined by the maximum temperature difference
DT between the device and ambient environment and the heat flux q
as parameters for evaluating the severity of heat removal, it is apparent
that we must urgently develop a low-heat resistance technique fordissipating heat.
To achieve this, Tuckerman, et al., proposed a method forremoving heat from electronic devices using microchannels, clarifying
the heat transfer characteristics and indicating the effectivenessthereof. This technique can conceivably be applied not only to coolingof electronic devices, but also to high-performance micro heatexchangers and the like. While related research activities are being
actively pursued, the use of this technique is not yet practical for suchapplications. This is because heat transfer characteristics of
microchannels have not been sufficiently sorted out and the concept
and technologies for applying this technique have not been organized
in a form readily understandable by technicians and researchers offields outside of thermal engineering.
From this background, we studied a microchannel cooling

Progress in microfabrication technology has spurred advances inthe density and performance of electronic devices, typified by the CPU,and has increased the power of semiconductor lasers. At the sametime, we have seen developments in R&D on micromachines,microreactors, and other micro-equipment, as well as in appliedresearch using this equipment. A problem common to all these devices
that has been raised is how to dissipate heat with high heat flux frommicro-domain. The heat dissipation from microprocessors around theyear 2006, for example, is projected to be about 100 W/cm2. That fromhigh-power diode lasers is estimated to reach 100-500 W/cm2, while theAPS, a next-generation X-ray source, is expected to reach 2000 W/cm2.
In order for these devices to operate properly, a large amount of heatgenerated therein must be removed to maintain a low temperature(about 100; or less). It is an extremely severe requirement to remove
high heat flux under a law temperature difference. In fact, technology
used in extreme thermal environments, such as to protect a space
shuttle reentering the Earth's atmosphere or nuclear reactor barriers
wherein it is necessary to dissipate heat of high heat flux under a hightemperature difference, is said to be insufficient to remove heat4

that phase change caused a large pressure loss.
(4) Microchannel cooling characteristics were clarified when using
water or air as the working fluid, and factors coming out whenusing air were noted. Next, we described our views on conducting
an optimal thermal design of the microchannel heat sinks and gavean optimal design rule.
(5) In order to evaluate quantities of heat transfer characteristics forthe microchannels, it is necessary to perform accurate
measurements of each physical quantity. From this perspective,
we summarized methods of measuring flow rate, velocity,temperature, and pressure and provided example.
(6) Techniques for reducing flow resistance and enhancing heattransfer are important for increasing the microchannel'sperformance. We studied techniques that have been proposedthus far and investigated their applicability to microchannels.
(7) Lastly, we provided various examples of microchannel production
and practical use.

technique from the perspective of designing microchannel heat sinks.
This paper, entitled "A Study on Applied Technologies forMicrochannels," reports the following.
(1) Asserting that microchannel cooling technology differs fromconventional cooling technology in that it has a smaller thermalresistance, we indicated why the use of microchannels can achievea low thermal resistance. We also clarified in which cases it is best
to use microchannel cooling technology, by organizing eachcooling technology's scope of application according totemperature and heat flux.
(2) A theoretical analysis was conducted on the heat transfer in
microchannels and the basic characteristics of heat transfer weregiven. We also described the scope of application of experimental
correlations for conventional systems and factors that come out
when using microchannels.
(3) We described the heat transfer and flow characteristics ofmicrochannels with or without a phase change and pointed out

Elucidating Fluid Phenomena in Microchannels
and Studying Applications of Microchannels in
Micromachine Technology
Teruo Fujii
Associate Professor,
Institute of Industrial Science, University of Tokyo
determines the driving force of the fluid in electroosmotic flow andexamples of measuring flow in microchannels using a particle image
velocimetry (PIV). An experiment using color reaction was performed toevaluate the mixing properties of a micromixer, while much research has
been reported on microfluidic devices, micropumps, microvalves, andmicromixers based on new principles and constructions are emerging.
Reports on microvalves include pneumatic normally-closed valves using
PDMS, a plurality of valves arranged in one channel that can be used as aperistaltic pump, horizontal valve structures formed by a DRIE process. A
new concept of microvalves using hydrogel was proposed. Reports on
micropumps included a diaphragm pump using a piezo bimorph actuator,
pumps using continuous electrowetting (CEW), and a bubble pump. Twokinds of micromixer are proposed ; one is using an electrohydrodynamic(EHD) effect to generate convention, and the other is using a bubble pumpto actively disturb the two-liquid interface.
Some example applications of microfluidic devices in genome/proteome
analysis are already being implemented. In the example of incorporating
capillary electrophoresis on a microchip, ninety-six microchannels arearranged radially to perform high-speed processes. Products emerging withan eye to the market include sixteen microchannels formed on a 4-inch
wafer. Studies are being performed on integrating two-dimensional gel
electrophoresis, an important method in proteome analysis, and a mass
spectrometer on a microchip. Separation by protein electrophoresis has
been implemented on a microchip in an attempt to automate the proteome
analysis by connecting the microchip to a protein analyzer.
The end of this paper talks about the state of research in Europe,introducing IMTEK at the University of Freiburg and describing theresearch system there, as well as discussing the commercialization trends ofmicrosystems in Switzerland. In the future, it is important that we consider
how we can strategically construct systems such as those represented in
Switzerland from the research stage to production and commercialization inorder to further develop micromachine technology that has been fostered inJapan and to make such technology useful in the real world.

In relevant studies conducted thus far, it is clear that applications of
micromachine technology to systems aimed at chemical and biochemical
analyses and synthesis are progressing. There are now many studies being
conducted in this field. At the 4th International µTAS Conference held in
May 2000 at the University of Twente in the Netherlands, 134 papers
selected out of 230 contributed were presented. Nearly 500 people from 22
countries participated at the conference. There has also been a sharp
increase in research presentations on this field at conferences on MEMS,
Transducers, HPCE, and other conferences, indicating a definite increasing
interest in the topic.
In light of the above conditions, the present study again focused on
microscale fluid phenomena and microfluidic systems, the importance of
which is gradually being recognized. This year's study particularly
emphasized fluid behavior in microspaces, the characteristics of its chemical
reaction processes, as well as techniques for its measurement andevaluation. As a continuation of previous studies, we summarized examples
of developing microfluidic devices used as components in microfluidic
systems and their example applications to genome/proteome analysis. This
paper also includes information on European trends in this field.
Since the ratio of surface area to volume increases in microspaces,
forces incurred by the fluid, such as surface tension, are relatively large.
The fluid has a laminar flow due to its small Reynolds number. Chemical
reactions can be performed quickly and efficiently because the interface
between two different contacting fluids is relatively large; the distance ofmolecular diffusion can be shortened; and it is easier to uniformly control
such conditions as temperature.
In measuring and evaluating microscale flows, shear stress is the mostcommon measurement in flow fields on an object's surface. For a long time,shear stress sensors using a thin film heater were proposed. Electroosmotic
flow was used for pumping the fluid in electrophoresis on microfluidic
devices. However, determining the flow profile in this case is an importantmeasurement for evaluating a separating function . There have beenreports on experiments for studying the effects of the zeta-potential that5