Breakfast DINING HALL SMIT Program Committee

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Microsensors and Microactuators
for Minimally Invasive Diagnosis
and Therapy
Yoichi Haga, Tohoku University,
Japan
Tadao Matsunaga, Wataru Makishi,
Masayoshi Esashi, Tohoku University
Biomedical Engineering Research
Organization (TUBERO), Japan
Background
Endoscopes and catheters are already
widely used and new more precise
examinations and diagnoses are
required. Small medical devices with
several functions for use in the human
body can be realized installing
microsensors and microactuators in the
medical devices.
Material & Methods
We have developed microsensors and
microactuators for minimally invasive
examinations and therapies using
MEMS and related microfabrication
technologies.
Results
A fibre-optic pressure sensor of 125
um in diameter has been developed for
monitoring local pressure in a very
narrow space in the human body. A
forward-looking ultrasound imaging
probe has been developed for
intravascular surgery. A focused
ultrasonic therapeutic device has been
developed for sonodynamic therapy
and sonoporation in the human body.
An active bending catheter using a
shape memory alloy actuator has been
developed for precise manipuration. A
laser scanning micro tool has been
developed for precise surgical
treatment in the human body. Maskless
photolithography system on
cylindrical substrates has been
developed for realization of high-
performance and multi-functional tube-
shaped micro medical devices.
Conclusion
There is a demand for technology
which can enable improved diagnosis
and treatment. MEMS and related
microfabrication technologies make
conventional procedures easier and
more precise.
Keywords
minimally invasive treatment,
micromachining, MEMS, catheter,
endoscope

Safety Assessment of SMA
Artificial Anal Sphincters
Yun Luo, Masaru Higa, Tohoku
University Biomedical Engineering Research Organization, Japan
Shintaro Amae, Hiromu Tanaka,
School of Medicine, Tohoku University,
Japan
Takeshi Okuyama, Toshiyuki Takagi,
Institute of Fluid Science, Tohoku
University, Japan
Tomoyuki Yambe, Institute of
Development, Aging and Cancer,
Tohoku University, Japan
Yasuyuki Kakubari, Hidetoshi Matsuki,
School of Engineering, Tohoku
University, Japan
Background
As prosthesis to assist the bowel
movement control of patients with
severe fecal incontinence, an artificial
anal sphincter is considered an eventual
choice. A novel artificial anal
sphincter using shape memory alloys
(SMA) was developed by the authors
and its functionality has been
confirmed. Safety assessment of the
device is required to make it closer to
clinical trials.
Material & Methods
The SMA artificial sphincter consists
of two SMA ribbons connected by
hinges and can be fitted around
intestinal canal, forming a sandwiching
occlusion to maintain the continence.
Thermally controlled deformations of
the SMA ribbons play a role for the
opening and closing functions in this
device. The power for the thermal
change is provided by a transcutaneous
energy transmission system. A
mechanical locking mechanism was
integrated into the system to shorten
the heating time and therefore to
eliminate the risk of heat burns which
has been a main concern in such a
thermally driven device. The safety of
the device has been examined by in
vivo experiments.
Results
The safety of the device has been
confirmed in a series of animal
experiments. At autopsy of
implantation experiments lasted up to
3 months neither postoperative
infection nor heat burns were found
around the artificial sphincter and the
secondary coil inside body, implying
the long-term safety of the system for
practical use.
Conclusion
Improvement of the device completely
eliminated the risk of heat burns. The
new design has fewer parts and makes
the device much easier to be implanted
and less invasive. Findings from the
long-term implantation in animal
models suggested the safety of
developed SMA artificial sphincters.
Keywords
shape memory alloy, artificial
sphincter, long-term implantation,
safety

This research is supported by the
Special Coordination Funds for
Promoting Science and Technology
from the Ministry of Education,
Culture, Sports, Science and
Technology, Japan.

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