An Electro-Thermal Actuation Method for Resonance Vibration of a Miniaturized Optical-Fiber Scanner for Future Scanning Fiber Endoscope Design

Aydin Aghajanzadeh Ahrabi,Yasong Li,Pierre Lane,Carlo Menon,Mandeep Kaur

doi:10.3390/act8010021

Abstract

Medical professionals increasingly rely on endoscopes to carry out many minimally invasive procedures on patients to safely examine, diagnose, and treat a large variety of conditions. However, their insertion tube diameter dictates which passages of the body they can be inserted into and, consequently, what organs they can access. For inaccessible areas and organs, patients often undergo invasive and risky procedures—diagnostic confirmation of peripheral lung nodules via transthoracic needle biopsy is one example from oncology. Hence, this work sets out to present an optical-fiber scanner for a scanning fiber endoscope design that has an insertion tube diameter of about 0.5 mm, small enough to be inserted into the smallest airways of the lung. To attain this goal, a novel approach based on resonance thermal excitation of a single-mode 0.01-mm-diameter fiber-optic cantilever oscillating at 2–4 kHz is proposed. The small size of the electro-thermal actuator enables miniaturization of the insertion tube. Lateral free-end deflection of the cantilever is used as a benchmark for evaluating performance. Experimental results show that the cantilever can achieve over 0.2 mm of displacement at its free end. The experimental results also support finite element simulation models which can be used for future design iterations of the endoscope.

Highlights

Visualization of internal organs using endoscopy is the most effective and direct method to localize lesions that require further diagnostic tests or treatment
This study setssets out out to assess the performance of the of thermally actuatedactuated micromicro-cantilever design and evaluate the magnitude of lateral tip displacement achievable at cantilever design and evaluate the magnitude of lateral tip displacement achievable at sufficiently sufficiently high enough resonance frequency to meet the performance goals set for the project
The tip displacement increased linearly with increased cyclic thermal base excitation, and longer bridges resulted in larger magnitudes of displacement; the bridge acted as a low-quality factor resonator

Summary

Introduction

Visualization of internal organs using endoscopy is the most effective and direct method to localize lesions that require further diagnostic tests or treatment. Endoscopes come in various configurations, each with different features and each optimized for the portion of the body they are designed to examine; the basic shape and the layout of the instrument are relatively unchanged since they were first introduced. Endoscopic technologies provide real-time video of the organ surface with relatively high resolution, they require direct access to the internal body cavity or organ being examined. What medical procedures can be performed by endoscopes on which parts of body or organs are dictated by the insertion tube diameter. The insertion tube diameter of the endoscope should be as small as possible, to minimize discomfort to the patients and reduce

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