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Gen Hashiguchi Laboratory
Intelligent Formative Engineering Course, Faculty of Engineering, Kagawa University
Gen Hashiguchi, Professor, Kagawa University
I hope to work on developing a functionalized AFM
probe for use in a solution so as to be able to link thistechnology to biotechnology research. Recently AOIElectronics Co., Ltd. has begun manufacturing andselling MEMS tweezers. They have made innovations
not only in the MEMS part but in the control system aswell. This device can be used for sample transport intransmission electron microscopes and in the recoveryof foreign matter generated in manufacturing
processes. The AFM tweezers will also likely beincorporated in products in the near future. It is myhope that the use of MEMS tweezers in AFM devices
will become commonplace.

In my laboratory, we have been developing devices
for nanotechnology research that combine nanoprobeswith MEMS to produce new functions. My firstopportunity to study probes dates back to my earlyyears working at a company. The company had apolicy of proposing research topics to the junioremployees in their second year so I began researching
field emission displays, which was beginning to attract
attention in those days. Primarily, I was etchingsilicon by a wet etching process to manufacture arraysof silicon electron guns. While silicon electron guns
were normally manufactured by controlling the underetching time with a circular mask, I wondered if theelectron guns could not be produced without underetching. My idea was to combine local oxidation with
KOH etching. By performing anisotropic etching with
KOH on pattern edges to expose the crystal face andsubsequently protecting the face with an oxide film
and repeating this process three times, I could
produce an excellent needle shape with good
uniformity and reproducibility. Moreover, when using
the edges of the pattern, this process is not dependent
on the precision of lithography. While the siliconelectron guns formed through this technique had good
properties, ultimately silicon did not come to be used
for electron guns.

On a different subject, I read the transcript of a
nanotechnology talk given by the well known
physicist Richard Feynman in which he describes
miniaturization achieved by first creating a mechanism
on a scale of one-fourth and subsequently creating amechanism at a scale of one-fourth the firstmechanism, for an overall scale of one-sixteenth.
Through the development of scanning probe
microscopes, we are currently capable of manipulating
atoms and molecules with a probe. However, we mustalso deal with the so-called meso-spaces in whichantagonistic micromechanical forces such as
electromagnetic forces and meniscus forces are quite
complex. For example, it is possible to grip but notrelease some samples with AFM tweezers, and we are
currently laboring over this resolution.

After taking up my new position at the University, I
continued studying probe devices based on thistechnique. Through similar processes, we haveproduced DNA tweezers (currently being studied in aJapan Science and Technology Agency project on thedevelopment of systems and technology for advanced
measurement and analysis) for stretching and fixing
DNA, a nanoknife for cutting chromosomes, and AFM
tweezers (currently being studied by the Consortium
Research & Development for Regional Revitalization
under METI) for gripping and recovering
nanomaterial. Wet etching is advantageous for
producing nanostructures reliably and at a low cost,with good uniformity over a large surface area.

At this point, we have created micro-sized cutting
mechanisms and handling mechanisms through MEMS
aimed at applications in nano-spaces. While at last wecan see the “bottom” in terms of miniaturizing
mechanisms, I suspect we have a long battle ahead ofus before we can produce nano-mesomechanicalstructures with micro-mechanisms.

I have also focused on self-sensitive AFM probes
using the immittance properties of comb actuators.
This probe uses variations in a resonant frequency
produced when an atomic force is applied to a comb
actuator subjected to self-excited vibrations in acircuit similar to a crystal oscillator. Currently we areable to produce two-dimensional images with thisprobe. In addition to its application as an AFM probe,
this technology can also be used as a touch sensor orforce sensor by applying the same principles totweezers, and is being developed for such applications
as cell tweezers used to grip soft material. Eventually

AFM tweezers
Comb-drive
probe

Integrated analysis system

Cell tweezers
Multi-probe

NanotechnologNanotechnology
DNA tweezers

Biotechnology
Biotechnolog

Electron gun
Knife probe

Collaboration among industry,
academia, and government6