Using an instrumented surgical tool, high-precision recordings of hand tremor were taken during vitreoretinal microsurgery. The data obtained using a compact, custom sixdegree-of-freedom inertial sensing module were filtered and analyzed to characterize the physiological hand tremor of the surgeon. Tremor during the most delicate part of the procedure was measured at a vector magnitude of 38 pm rms. Nontremulous, lower-frequency components of instrument movement were also characterized. The data collected provide an important baseline for design specification and performance evaluation of engineered microsurgical devices.

Abstract-The authors describe a minimally invasive flexible needle-steering system to access deep areas of the brain. The design exploits the inherent bending of a beveled-tip needle when passing through tissue. Precise control of the rotation of the needle allows for an unlimited variety of trajectories. Potential advantages to this system include the possibility of catheter-based therapy delivery within the brain with minimal trauma to surrounding structures, and the ability to navigate around critical cerebral structures to reach deep zones within the brainstem, thalamus or other subcortical regions.

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Overall manual accuracy and motion frequency in simulated microsurgery have been studied. Eye surgeons were tested in two tasks: attempting to hold an instrument still, and repeatedly actuating. Rms error and overall motion range were measured. Spectral analysis was also performed. The average rms error was 49 µm and 133 µm, respectively, for the two test conditions, and the average range of motion while trying to hold still was 202 µm. Substantial low frequency motion occurred under both conditions. On average, 98.9% of the total power of voluntary movements tested was found to be below 2 Hz.

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