光纖彎曲感測器研發與應用

Abstract

根管治療過程中，由於根管彎曲的情形而使得鎳鈦旋轉器械在治療過程中會有彎曲形變發生，而有壓應力及張應力施加鎳鈦旋轉器械上，如此的情況會導致鎳鈦旋轉器械的疲勞斷裂。為了有效預測鎳鈦旋轉器械的疲勞壽命，根管的彎曲度為重要的因素之一。本研究的目的即為發展一光纖彎曲感測器以量測根管的彎曲度，而推論出位於根管內鎳鈦旋轉器械的彎曲程度。 本光纖感測器的感測元件為製作一緊縮區段於光纖的末梢區域，與一金屬薄膜鍍於光纖的末端以反射光訊號。本研究使用了三種不同緊縮區段的緊縮直徑，分別為原本光纖直徑的30%、50%、以及 70%，校正的結果顯示不同的緊縮直徑對彎曲有不同的敏感度。本光纖感測器的感測機制為當光纖彎曲感測器的末梢區域受到彎曲時而光訊號會產生衰退，根據不同反射光訊號的能量衰退可以計算出不同的彎曲度。實驗結果也顯示位於根管內鎳鈦旋轉器械的彎曲程度和本光纖感測器量測出的彎曲度吻合。

Due to the curved geometry of the root canal, the Ni-Ti rotary instruments are under rotating bending condition during the root canal treatment, which incurs alternating tensile and compressive stresses in the instruments. Such an alternating loading will lead to fatigue fracture. To predict the remaining life of a Ni-Ti rotary instrument, it is important to know curvature of the root canal. The purpose of this study was to develop fiber optic curvature sensors for measuring curvature in the root canal and deduced the curvature of a Ni-TI rotary instrument. The sensitive element of the curvature sensor was by fabricating one necked segment disposed within the distal section of the optical fiber and a metallic film was deposited on the distal end for reflecting light signal. The reduced diameters 30%, 50% and 70% of the original optical fiber were employed. The calibration results show that different reduced diameters displayed different sensitivities in curvature. The sensing mechanism of the curvature sensor was that when the distal section of the curvature sensor was bent so that attenuation of light signal occurred. Thereby the curvature could be evaluated in accordance with the amount of energy attenuation in the reflected light signal. The experimental results also show that the deduced bending curvature agreed well with the instrument curvature inside the canal.