This paper proposes a new handheld laparoscopic forceps manipulator for laparoscopic surgery using 2 bending mechanisms by multi-slider linkage mechanisms to achieve high mechanical performance and applicability. A bending mechanism consisted of 3 outer frames, 2 rotating joints and 2 sliding linkages for drive and restraint. The rotation of the joint was available by pulling/pushing the adjacent element by sliding linkage in order. We connected 2 bending mechanisms, one was for the horizontal plane bending and the other was for the vertical plane bending, enabling 2-DOFs independent motions between -90 degrees and +90 degrees. The 2-DOFs bending mechanism and 1-DOF forceps mechanism were driven by 3 brushless DC-servomotors. We examined the actual angle of 2-DOFs bending mechanism, obtaining repeatability of ±0.87 degrees in the horizontal plane bending and ±0.91 degrees in the vertical plane bending. In an animal experiment this manipulator performed laparoscopic surgical tasks under pneumoperitoneum. In conclusion, we were sure of a usefulness of multi-slider linkage mechanisms for the new handheld forceps manipulator to clinical application, which showed high repeatability of less 1.0mm manipulation and large working space with sufficient generated power of end-effector.
We evaluated the mechanical properties of biodegradable microstructures produced by a three-dimensional microfabrication system that we had developed. Biodegradable materials are indispensable in developing modern medical equipment, but the lack of a suitable processing method is hindering the application of these materials. Our fabrication system has achieved a high resolution (50μm) and the high bio-applicability of the fabricated structure has been verified bycultivating cell lines in a biodegradable vessel fabricated using our system. However, the mechanical strength of the fabricated structure had been unknown. To measure the mechanical strength of our structures, we fabricated test pieces using Poly (D, L-lactide-co-glycolide), and subjected them to a tensile test. In order to evaluate the mechanical strength of the structures, two types of test piece were prepared, one scanned parallel to the tensile direction, and the other scanned perpendicular to it. The strength of our fabricated ructure was shown to be about 55 percent of the tensile strength of structures made from the same material but fabricated using the conventional method. Our fabrication system is expected to find applications in tissue engineering in the near future.
The purpose of this study is measurement of forces exerted during the robotic needle insertion into human vertebra and comparison between robotic and manual needle insertion. Axial forces exerted during robotic insertion into human vertebrae fixed with water solution of formaldehyde did not exceed 25 N when the feed rate was no more than 0.5mm/s. There was no statistically significant influence of formaldehyde fixation on axial forces exerted. The forces exerted during robotic insertion were as small as less than 50% of those during manual insertion partly because of sufficiently wide angle of the needle twisting.
Purpose: The aim of this study was to analyze the mandibular movement of a patient with square mandible using the 4-dimensional (4D) analyzing system, and to suppose the cause of square mandible from characteristics of the movements. Method: Subjects were a healthy volunteer and a patient with square mandible. A volunteer was a 26-year old female who had no missing teeth and no morbid findings in clinical examination. A patient was a 37-year old female. Diagnostic imaging scarcely depicted any disc derangement, but a severely limited jaw opening was noted. As well, her facial appearance showed a characteristic square mandible facial configuration. The skull and mandible were reconstructed into a 3-dimensional (3D) bone model from the CT data and mandibular movements were recorded by a measurement device of MM-JI-E (Shofu Inc.). The bone model and the mandibular movements were combined using the 4D analyzing system. The origin and halt of each masticatory muscle were positioned on the surface of the 3D bone model, and connected together with a string respectively. In this system, the color of the string was designed to be passively changed in accordance with mandibular movements. Results and Discussion: In this case, the cause of opening limitation was not the opening muscle itself but contraction of the temporal muscle. Therefore, it was supposed that the load extended to the masseter muscle from the temporal muscle depended on the masseter muscle, and resulted in muscle hypertrophy or angle hyperplasia.