Bending mechanism using SMA wires for transurethral lithotripsy

Toshiki Tachioka, Tadao Matsunaga, Yoshikatsu Tanahashi, Takumi Kobayashi, Yoichi Haga

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


In the transurethral lithotripsy using flexible endoscope (f-TUL), a flexible ureteroscope is inserted into the bladder from the urethra and breaks calculus by laser transmitted through an optical fiber. Because laser irradiation position is fixed in the endoscopic field of view, it is difficult to perform precise alignment of laser to the target when the target has relatively complex structure. To solve the problem, a thin multidirectional active bending mechanism of the laser fiber using Shape Memory Alloy (SMA) wire has been developed. This device has 170 μm diameter channel for laser fiber and is controlled by 3 SMA wires. Maximum outer diameter is 1.1 mm and length of the bending part is 10 mm. The fabricated bending mechanism with laser fiber bends up to 10 degrees. Surface temperature was measured by using a thermocouple in water bath and was lower than 41°C.

Original languageEnglish
Pages (from-to)41-47
Number of pages7
JournalIEEJ Transactions on Sensors and Micromachines
Issue number2
Publication statusPublished - 2018


  • Bending mechanism
  • Shape memory alloy
  • Transurethral lithotripsy

ASJC Scopus subject areas

  • Mechanical Engineering
  • Electrical and Electronic Engineering


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