Real-time thickness measurement of biological tissues using a microfabricated magnetically-driven lens actuator

Abstract

A fiber optic confocal catheter with a micro scanning lens was developed for real-time and non-contact thickness measurement of biological tissue. The catheter has an outer diameter and rigid length of 4.75 mm and 30 mm respectively and is suitable for endoscopic applications. The catheter incorporates a lens actuator that is fabricated using microelectromechanical systems (MEMS) technology. The lens is mounted on a folded flexure made of nickel and is actuated by magnetic field. Thickness measurements are performed by positioning the catheter in front of the tissue and actuating the lens scanner in the out-of-plane direction. A single-mode optical fiber (SMF) is used to deliver a 785 nm laser beam to the tissue and relay back the reflected light from the tissue to a photomultiplier tube (PMT). When the focal point of the scanning lens passes tissue boundaries, intensity peaks are detected in the reflecting signal. Tissue thickness is calculated using its index of refraction and the lens displacement between intensity peaks. The utility of the confocal catheter was demonstrated by measuring the cornea and skin thicknesses of a mouse. Measurement uncertainty of 8.86 µm within 95% confidence interval has been achieved.

Flexible Interdigital Sensor for Nondestructive Detecting Wear and Thickness of Tire Tread

“…In addition, thickness sensors have applications in health management. The thickness of biological tissue can be measured by a fiber optic confocal catheter [13]. The demand for sensors has [14].…”

Numerical and Experimental Performance Analysis of the Chirped Fiber Bragg Grating Based Abrasion Sensor for the Maintenance Applications in the Industry 4.0

“…Another type of wear sensor is material thickness sensors recording the wear of a tool or abrasive element. This type of sensor can be based on electro-magnetic fields [19], radiographic methods [20,21], system of lenses [22] or optical fiber sensors [23][24][25][26][27][28]. However, for specific applications, utilization of the classical electronic sensor is impossible.…”

Histology-Equivalent Vertical Optical Sectioning Using a 2-Axis Magnetic Confocal Microscanner

“…Recently, a group has proposed direct vertical imaging by mounting a micromirror on a stage, actuated in the axial direction using piezoelectric unimorph beams [8]. We have previously reported a magnetic actuator for moving a lens in the axial direction and used it for measuring thickness of biological samples and transparent films [9][10][11].…”