Virtual reality (VR) technology plays a significant role in many biomedical applications. These VR scenarios increase the valuable experience of tasks requiring great accuracy with human subjects. Unfortunately, commercial VR controllers have large positioning errors in a micro-manipulation task. Here, we propose a VR-based framework along with a sensor fusion algorithm to improve the microposition tracking performance of a microsurgical tool. To the best of our knowledge, this is the first application of Kalman filter in a millimeter scale VR environment, by using the position data between the VR controller and an inertial measuring device. This study builds and tests two cases: (1) without sensor fusion tracking and (2) location tracking with active sensor fusion. The static and dynamic experiments demonstrate that the Kalman filter can provide greater precision during micro-manipulation in small scale VR scenarios.

This article presents a Lissajous scanning confocal endomicroscopy comprising an easily manufacturable thin polyimide (PI) film and modified phase-offsetdriven scanning. The Lissajous scanning confocal probe has a piezoelectric tube actuator and the PI film-attached fiber cantilever designed to resonate with the lever mechanism. Data from a finite element analysis and experiments are used to optimize the dimensions of the PI film, which produces a frequency separation and field of view of 195 Hz and 180 µm × 180 µm, respectively, at driving voltages less than 30 V pp . The best combination of decimal frequencies with optimized driving phase offsets is determined to achieve a scanning density (SD) exceeding 80% consistently with an imaging speed of 8 Hz. By analyzing the Lissajous patterns at different decimal frequency combinations via time-delay analysis, it is possible to find more diverse combinations that meet the SD criterion. When the scanning patterns deviate from the desired paths, the proposed modified phase-offset-driven method is applied to maintain the best scanning pattern. The USAF 1951 test pattern, several plants, and rat gastrointestinal tract were imaged successfully using the confocal endomicroscopic system with the PI film and modified phase-offset-driven scanning.

We present a SMART injector with two parallel common-path optical coherence tomography fibers to enable angle measurements and injection depth corrections for oblique subretinal injection. The two optical fibers are attached to opposite sides of a 33 G needle with known offsets and designed to pass through a 23 G trocar that has an inner diameter of 0.65 mm. By attaching a SMART system to a rotational stage, the measured angles are calibrated for minimal error from reference angles. A commercial eye model was used to evaluate the control performance, and injection experiments were performed on a phantom made of agarose gel and a porcine eye.

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