Wataru Makishi

Active Bending Electric Endoscope Using Shape Memory Alloy Coil Actuators

Bending motions of the tip of a conventional endoscope are controlled from outside the body by wire traction. A shaft of an endoscope should be relatively hard to avoid buckling by wire traction. Therefore, precise operation of the endoscope is difficult in complex shape areas such as the intestine. Furthermore, patients suffer pain during a procedure with an endoscope. An active bending electric endoscope using shape memory alloy (SMA) actuators has been fabricated. A CCD imager (410,000 pixels) is mounted at the end of the endoscope, and the tip has an omni-directional bending mechanism using three SMA coil actuators. The SMA coil actuators contract by supplying electrical current and bend the endoscope. The bending mechanism is controlled by a joystick from outside the body. The external diameter of the fabricated endoscope is 5.5 mm. The maximum bending angle of the fabricated endoscope is 90deg (curvature radius: 29 mm). The observation of the inside of a blood vessel model by the CCD imager of a fabricated endoscope is confirmed, The shaft of the fabricated endoscope, which is realized using SMA coil actuators instead of a traction wire, is soft. Therefore, the precise observation of a deep area of the small intestine with the fabricated endoscope might be possible without the patient suffering pain

Minimally invasive diagnostics and treatment using micro/nano machining

Several medical tools with various functions have been developed for minimally invasive diagnostics and treatment. Microfabrication techniques such as MEMS technology are useful for the realization of high‐performance multifunctional minimally invasive medical tools with small sizes. An ultra‐miniature pressure sensor and an intravascular ultrasonic forward‐viewing imager have been developed as microsensors for use in the human body. Active bending catheters have been developed for steering catheter tips without using traction of wires from outside the body. An ultrasonic therapeutic tool for sonodynamic therapy and sonoporation, and a micro scanner for precise laser treatment have been developed as therapeutic tools for use in the human body. High‐functionalized endoscopic tools and catheters will enable more precise and safe diagnostics and therapy, as well as novel diagnostics and treatment which have been impossible to date.

Fabrication Techniques for Multilayer Metalization and Patterning, and Surface Mounting of Components on Cylindrical Substrates for Tube-Shaped Micro-Tools

This paper reports fabrication techniques for multilayer microstructures and surface mounting of small components on cylindrical substrates for tube-shaped high-performance micro-tools. A cylindrical shape is an ideal shape for micro medical tools inserted temporarily or implanted in the human body. Miniaturization, multifunctional capabilities, and high-performance are required for these tools. Tubular lumens, which are useful for the insertion of medical tools and for the injection of drugs, are necessary for endoscopes and catheters. Micro-fabrication on cylindrical substrates meets these demands. Multilayer metallization and patterning, as well as three-dimensional resist patterning have been performed using maskless lithography techniques on glass tubes with 2 and 3 mm outer diameters. Using laser soldering techniques, a high-speed OP amp has been mounted on a multilayer circuit formed on a glass tube to amplify small signals from micro medical sensors. These techniques will realize multifunctional and high-performance tube-shaped micro medical tools with small diameters

Magnetic torque driving 2D micro scanner with a non-resonant large scan angle

In this paper, a non-resonant 2D optical scanner with extremely large optical scan angle has been reported. A mirror, which is supported with a double-gimbal structure, is inclined by a rotational magnetic torque. Two of four permanent magnets are mounted on the mirror and the gimbal, respectively. The scanning angle of two axis can be controlled independently using external electromagnets. A static drive with maximum optical scan-angle of 118 degree has been achieved.

Development of active catheter, active guide wire and micro sensor systems.

Active catheters and active guide wires which move like a snake have been developed for catheter-based minimally invasive diagnosis and therapy. Communication and control IC chips in the active catheter reduce the number of lead wires for control. The active catheter can be not only bent but also torsioned and extended. An ultra minature fiber-optic pressure sensor, a forward-looking ultrasonic probe and a magnetic position and orientation sensor have been developed for catheters and guide wires. These moving mechanisms and several sensors which are fitted near the tip of the catheter and the guide wire will provide detailed information near the tip and enable delicate and effective catheter intervention.

Mechanical strengthening of silicon torsion bar of MEMS scanning mirror by hydrogen anneal

This paper reports on the strengthening effect of hydrogen anneal on torsional fracture strength of single crystal silicon (SCS). Moving-magnet-type MEMS mirrors were prepared by fabricating SCS and silicon on insulator (SOI) wafers via deep reactive ion etching (DRIE) as fracture test specimens. As a result of the fracture test of the torsion bar on the mirrors, the torsion bar fabricated using a SCS wafer could be strengthened to about 4 times in average by hydrogen anneal. By contrast, that using a SOI wafer was weaken to half. This mechanical strengthening effect has the potential ability to provide highly-reliable and tough SCS-based MEMS devices.

Piezolectric 2D micro scanner for minimally invasive therapy fabricated using femtosecond laser ablation

Piezoelectric two dimensional (2D) micro scanner was developed for medical laser scanning micro tool that is inserted in the human body and observes tissue microstructures optically and scans laser for treatment. The structure of developed micro scanner consists of three piezoelectric unimorph cantilevers, a mirror, three flexible joints and a pivot. The joints link the end of the unimorph cantilevers with the mirror. The size of the micro scanner part is 1.6 mm/spl times/5.0 mm, and the thickness is 100 /spl mu/m. The mirror tilted in two dimensions and maximum tilting angle was 2.23 degree when 60 V was applied. The 2D scanner and optical system will be packaged in a tube of 2 mm diameter which can be inserted in a working channel of a conventional endscope.

Electromagnetically driven ulutra-miniature single fiber scanner for high-resolution endoscopy fabricated on cylindrical substrates using mems process

An electromagnetically driven single fiber scanner for high-resolution visual inspection in narrow spaces of the human body was developed. This scanner consists of a single fiber and driving coils. The driving coils are photofabricated on the 1.08-mm outer diameter of a thin polymer tube, and a cylindrical permanent magnet is fixed on the fiber. The fiber is positioned at the center of the tube on which the driving coils are photofabricated. When an alternating current at the resonance frequency is supplied to the coils, the permanent magnet which is fixed to the fiber is scanned electromagnetically and two-dimensionally. In this study, spiral scanning and OCT imaging were demonstrated.