Enhancing Ocular Precision: A Tactile Force Feedback-Enabled Handheld Cyclodialysis Spatula for Eye Surgery

This article presents a double-ended cyclodialysis smart spatula integrated with force sensors for tactile force feedback during ophthalmic surgery. The smart spatula consists of two tri-axis tactile force sensors that utilize the fringe effect of electric field lines generated between the stationary patterned electrodes to measure input force at the smart spatula needles on both ends. Both the tactile force sensors and smart spatula structure are fabricated using cost-effective additive manufacturing technology. The needle tips both ends of the smart spatula and its overall length and diameter confirm the standard sizes used in conventional handheld spatulas. The integrated force sensors, within the smart spatula, can measure both the normal and shear forces applied at tips of the needles with a maximum input force range of 2 N for the normal direction and 0.5 N for the shear direction, achieving a force resolution of 10 mN. The normalized capacitance change sensitivity for the force sensors is measured to be 0.045/N and 0.007/N in the normal and shear directions, respectively. An embedded system has been developed for the real-time processing of force measurement data from the integrated force sensors in the smart spatula. This system enables wireless transmission and display of the data for the surgeon during delicate surgical procedures such as cataract surgery, corneal transplantation, and epiretinal membrane peeling where tool-tissue forces are generally below 1 N. A graphical user interface (GUI) is developed for visualization of the force and direction to assist the surgeon. The smart spatula has a response time in milliseconds between the actual force applied and its display on the GUI.