Development of the SAIT single-port surgical access robot--slave arm based on RCM mechanism.

An innovative single-port surgical robot has recently been developed by the Samsung Advanced Institute of Technology (SAIT). The robot can reach various surgical sites inside the abdominal cavity from a single incision on the body. It has two 7-DOF surgical tools, a 3-DOF endoscope, a flexible hyper-redundant 6-DOF guide tube, and a 6-DOF manipulator. This paper primarily focuses on the manipulator, called a slave arm, which is capable of setting the location of a Remote Center Motion (RCM) point. Because the surgical tools can explore the abdominal area through a small incision point when the RCM point is aligned with the incision area, the RCM mechanism is an integral part of the manipulator for single-port surgery. The mechanical feature, operational principle, control method, and the system architecture of the slave arm are introduced in this paper. In addition, manipulation experiments conducted validate its efficacy.

Growth of the transient planar state in cholesteric liquid crystals.

Growth and propagation of the transient planar state in the transition of cholesteric liquid crystals from the homeotropic to the planar state was investigated by both experiments and numerical simulations for planar boundary conditions. Interference fringes observed in the measured reflection spectra during the evolution of the transient planar state have not been reported in the previous study. These interference fringes caused by a Fabry-Perot interferometric structure formed in the cell show that the transient planar state grows from the surfaces and propagates toward the bulk region in the planar sample. Our experimental results for the growth of transient planar state in planar boundary conditions are consistent with the previously reported simulation studies.

Comparison of pressure dependence of electron energy distributions in oxygen capacitively and inductively coupled plasmas.

Electron energy distribution functions (EEDFs) were measured with increasing gas pressure in oxygen capacitively and inductively coupled plasmas. It was found that, in the capacitive discharge, abnormally low-energy electrons became highly populated and the EEDF evolved to a more distinct bi-Maxwellian distribution as the gas pressure was increased. This pressure dependence of the EEDF in the oxygen capacitive discharge is contrary to argon capacitively coupled plasma, where--at high gas pressure--low-energy electrons are significantly reduced due to collisional heating and the EEDF evolves to the Maxwellian. The highly populated low-energy electrons at high gas pressure, which was not observed in inductively coupled oxygen plasma, show that collisional heating is very inefficient in terms of the oxygen capacitive discharge. It appears that this inefficient collisional heating seems to be attributed to a low electric field strength at the center of the oxygen capacitive plasma.