توری براگ فیبر باریک برای ابزارهای جراحی میکرو
Abstract
I. Introduction
II. Mechanical Structure
III. TFBG Working and Sensing Principle
IV. Experimental Setup
V. Results and Discussion
Authors
Figures
References
Abstract
Decoupling between axial and transversal forces is an essential during tool-tissue interaction in many medicine surgeries; in particular where fine and precise manipulation is required to save the delicate tissues. One example of which is the vitreoretinal microsurgery (VRMS). When fiber Bragg grating based sensing technique is utilized, the cross-talk noise between the axial and transversal forces always show up severely due to its conventional wavelength shift method. To address the challenge, we have introduced theoretical method in which a combination of tapered FBG (TFBG) and bandwidth modulation method instead are used. Here in this paper, first phase of our ongoing progress to proof the concept and validate the simulation results is demonstrated experimentally. We have developed a prototype incorporated TFBG mimicking the structure of the ophthalmia’s needle to measure temperature-insensitive 1-DOF axial forces. High speed plug and play (I-MON-256USB (Ibsen)) is used to monitor the reflection spectrum of the prototype sensor. An automated calibration system using LabVIEW with efficient algorithms have been developed to calculate and keep track the bandwidth variations as different values of axial forces applied. Calibration procedures are repeated three times to validate the consistency of the sensor response. Experimental results show that, the estimated force values of our prototype are consistent with their actual values with RMS error less than 0.356 N over the range (1N-10N), while temperature insensitivity is guaranteed.
Introduction
Tapered fiber Bragg gratings (TFBG) are getting popular in the field of strain sensor as it responds differently to the strain and temperature [1], [2]. While its central wavelength shifts due to temperature variation as conventional FBG does, its spectral width can be tuned when tension force is applied longitudinally because of the variable crosssectional area resulted from taper transition diameter. To this end, temperature-insensitive strain measurement is feasible. An additional advantage of TFBG is its tiny cross-sectional area, due to which a high sensitivity strain measurement is understandable. Measuring 3-axis force components with very high sensitivity (sub-mN) in vitreoretinal surgeries is of interest of many researchers/ophthalmologists. An interesting research utilizing FBG sensing technique for VRMS application, through which several development stages have been carried out in [3]–[۷] which led finally to highly sensitive 3-DOF instrument. Four standard FBG sensors have been integrated into customized ophthalmia’s needle-hook, one inner FBG is fixed on its either side at the neutral axis of the needle with two intermediate tubes, while the other three FBG sensors have been attached onto the needle’s surface. A force resolution of 0.25 mN was demonstrated in mentioned work using wavelength shift interrogation method (WSIM). For more details on development stages can be found in [8].