Column

MEMS-Enabling Technologies
Norihisa Miki, Assistant Professor,Department of Mechanical Engineering, Faculty of Science and Technology, Keio University
not a MEMS device in the strict sense of the term. However,patterning of arrayed electrodes, and processes to encapsulate
pigments and electrolytes are made possible through MEMS
manufacturing technologies. Thus the proposed system is an
MEMS-enabling technology. To date, we have succeeded in
detecting the movement of a pupil using a single dye-sensitizeddevice (patent application no. 2006-018591).

I joined the Department of Mechanical Engineering at Keio
University as assistant professor and launched the “MikiLaboratory,” the only laboratory for the field of MEMS in thedepartment, in April 2004. Currently we have nine graduate
students and five senior undergraduate students, and are
becoming a full-fledged laboratory.
When launching the new laboratory, I struggled first andforemost on determining the direction of our research. Before
coming to Keio University, I was a research engineer in theDepartment of Aeronautics and Astronautics at theMassachusetts Institute of Technology where we researched abutton-sized micro-engine and a micro-rocket in the MIT
Microengine Project. I was primarily involved in themanufacturing of and experimentation with devices and, inparticular, studied Deep Reactive Ion Etching (DRIE) andwafer bonding technologies that require rigid manufacturing
precision. I might be able to continue the work here at Keio
University, but a change in location is also a good opportunity
to change the subject of study. Therefore, emulating theresearchers in US, who customarily change their research
themes every 3-- 5 years, I decided to tackle a new topic ofresearch for the new laboratory at Keio.
When considering new topics of research, I remembered aterm used by Dr. Senturia, a former professor at MIT and now
the CTO at Polychromix: “MEMS-enabling technologies.” In hislectures, Dr. Senturia suggested that we should not sell only
MEMS devices but technologies that are made possible throughthe MEMS devices; that is, entire systems that incorporate theMEMS devices. (One can derive from this meaning that MEMS
devices alone may not be discriminated against the competitors
given their low cost accounting for only a few percent of theoverall system.)Hence, we searched not for MEMS devices, but for MEMSenabling technologies, i.e., technologies that would benefit
dramatically from MEMS and micromachining technologies. As
one example, we introduce a pupil-tracking and line-of-sight(LOS) detecting technology. The LOS detecting technology has
numerous promising applications in the fields of medical care,information technologies, and safety and security. For example,
the severely disabled who are capable of moving only their eyes
can utilize LOS to communicate with others. LOS can be a novel
input tool replacing the mouse and keyboard. Detecting theLOS of pedestrians, in particular, children, and drivers helps theeffective display of hazard signs. Most of today’s LOS detecting
systems, however, employ a stationary camera or a helmet witha camera mounted in the front to track the subject’s pupil,
which obstructs the subject’s movement and field of vision and,most importantly, affects the subject psychologically.
In light of these issues, we have been developing
transparent pupil-tracking devices that can be fabricated oneyeglasses, as shown in Fig. 1. We employed dye-sensitizeddevices, which are currently studied as solar cells, astransparent optical sensors to detect differences in reflected
light between the whites of the eyes and the pupils and thus
derive the position of the pupils. Since these devices can beworn as glasses, they do not obstruct the subject’s movement or
field of vision and have a negligible psychological impact,
thereby resolving the issues of today’s LOS detecting devices.
Hence, this technology will contribute to the rapid
implementation of the promising applications of LOS detection
mentioned above. Since the device has no movable parts, it isFig. 1 A mounted transparent pupil tracking device
When studying MEMS-enabling technologies, I believe it isvital that we make full use of the resources at the Faculty ofScience and Technology of Keio University. MEMS-enabling
technologies are, in effect, technologies of other fields that canmake remarkable advances with the help of MEMS. Hence, thekey for establishing a research theme lies in how we candiscover the potential needs in other fields. In this regard, theFaculty of Science and Technology at Keio University has beena blessing. Owing partially to the rather compact YagamiCampus at the university, we have enjoyed lively intercoursewith diverse researchers in the eleven departments of ourfaculty. Miki Laboratory is currently conducting collaborative
research with six other laboratories in four departments.
As you know, MEMS development is highly dependent on
expensive equipment. Miki Lab currently has equipment
capable of performing basic photolithography, but we do notpossess expensive DRIE or sputtering devices, nor do we havemeasuring instrumentation. Fortunately, however, our Facultyof Science and Technology has the Central Service Facilities for
Research complete with measuring instruments and analyzers(http://www.sfr.st.keio.ac.jp/), and a laboratory equipped with adeposition system. Hence, we have endeavored to share the useof this equipment as much as possible. At the same time, wehave made our facilities at Miki Lab available to otherlaboratories having an interest in MEMS. In the future I would
like to establish an open MEMS laboratory at the Faculty ofScience and Technology.
However, sharing resources in this way leads all too
frequently to some laboratories monopolizing the equipment,
establishing rules of usage that are too strict, and accidents
caused by inexperienced users. We are currently drawing up
management guidelines to eliminate these problems while
studying the systems used at MITs Microsystem Technology
Laboratories and MEMS laboratories in Japan. We are actively
engaged in implementing a research environment to facilitate
MEMS-enabling technologies, i.e., “a research environment
enabling MEMS-enabling technologies” in our Faculty ofScience and Technology.

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