Effects of micro-vibratory modulation during robot-assisted membrane peeling

In retinal microsurgery, membrane peeling is a standard procedure requiring the delamination of a thin fibrous membrane adherent to the retina surface by applying very small forces. Robotic devices with combined force-sensing instruments have significant potential to assist this procedure by facilitating membrane delamination through induced micro-vibrations. However, defining the optimal frequency and amplitude for generating such vibrations, and updating these parameters during the procedure is not trivial. Automatic adjustment of these parameters via an adaptive control scheme is possible only if the individual parameter effects on delamination behavior are known. This study presents an experimental exploration of how micro-vibration amplitude and frequency affect membrane peeling forces alone. Combining a micromanipulator and a force-sensing micro-forceps, several peeling experiments were done on artificial phantoms (bandages) and inner shell membrane of raw chicken eggs. In the tested range of micro-vibration frequencies (10-50 Hz) the average delamination force was minimized mostly at 30 Hz for the bandages and at 50 Hz for the egg membranes. Increasing the micro-vibration amplitude from 50 μm up to 150 μm provided further reduction in average force, thus facilitated membrane delamination.