Towards the development of a sub 500 micron thermally actuated scanning fiber endoscope for detection of lung cancer

Medical professionals increasingly rely on endoscopes to carry out many minimally-invasive procedures on patients in order to safely examine, diagnose and treat a myriad of conditions. However, their distal tip size dictates which passages of the body they can be inserted into and consequently what organs they can access. For inaccessible areas and organs, patients are often subjected to intrusive, risky and uncomfortable procedures; diagnosis of lung cancer is one of these cases. Hence, this study sets out to design an endoscope head that has an outer diameter of less than 500 microns, small enough to be inserted into the lungs. To attain this goal, a novel approach based on resonance thermal excitation of a dual clad single mode optical fiber at a location close to its base is proposed. The previously obtained analytical models for describing the lateral vibratory motion of the fixed-free micro-cantilever are used to validate the corresponding physical prototypes. Parameters such as choice of materials, resonance frequency, bonding methods, shape and dimensions of the actuator bridge, structural rigidity, assembly are considered in the physical design of the device. Lateral free-end deflection of the center fiber is used as a benchmark for evaluating performance. The results show that this novel proposal can be used to satisfy the project requirements.