Examination of needle surface corrosion in electroacupuncture.

BACKGROUND: Electroacupuncture (EA) is a modern form of acupuncture therapy where stainless steel acupuncture needles are used as percutaneous electrodes to apply electrical stimulation. The concern about electrolytic corrosion of needles during EA has not been conclusively addressed. AIM: To examine whether corrosion of stainless steel acupuncture needles occurs after EA to establish the safety profile of this therapy. METHODS: The study comprised four EA sessions on healthy participants mimicking a common clinical practice, with needle surface examinations conducted immediately after each session. Used acupuncture needles that did not undergo electrical stimulation and unused needles taken from the original package were also examined as control comparisons. Two commonly used types of single-use, silicone-coated, stainless steel needles were selected for the experiment. The ES-160 digital acupunctoscope (a charge-balanced electric stimulator) was used to deliver electrical stimulation, and an oscilloscope was used to record the waveforms and electric currents. All needles were sterilised before examination by a scanning electron microscope (SEM), where images of needle tips and shafts were taken for further analysis. RESULTS AND CONCLUSIONS: 32 needles were examined under the SEM. As the main findings, the SEM images showed the surface finish, burr attachments and surface characteristics of needle samples. No evidence of electrolytic corrosion was detected on any needle that underwent electrical stimulation for 30 min delivered by a charge-balanced acupunctoscope in healthy participants. The choice of a charge-balanced acupunctoscope is recommended to avoid any potential corrosion of needles in EA clinical practice.

Design of Hierarchical Structures for Synchronized Deformations.

In this paper we propose a general method for creating a new type of hierarchical structures at any level in both 2D and 3D. A simple rule based on a rotate-and-mirror procedure is introduced to achieve multi-level hierarchies. These new hierarchical structures have remarkably few degrees of freedom compared to existing designs by other methods. More importantly, these structures exhibit synchronized motions during opening or closure, resulting in uniform and easily-controllable deformations. Furthermore, a simple analytical formula is found which can be used to avoid collision of units of the structure during the closing process. The novel design concept is verified by mathematical analyses, computational simulations and physical experiments.

High-speed spinning disks on flexible threads.

A common spinning toy, called "buzzer", consists of a perforated disk and flexible threads. Despite of its simple construction, a buzzer can effectively transfer translational motions into high-speed rotations. In the present work, we find that the disk can be spun by hand at an extremely high rotational speed, e.g., 200,000 rpm, which is much faster than the previously reported speed of any manually operated device. We explore, both experimentally and theoretically, the detailed mechanics and potential applications of such a thread-disk system. The theoretical prediction, validated by experimental measurements, can help design and optimize the system for, e.g., easier operation and faster rotation. Furthermore, we investigate the synchronized motion of multiple disks spinning on a string. Distinctly different twist waves can be realized by the multi-disk system, which could be exploited in the control of mechanical waves. Finally, we develop two types of manually-powered electric generators based on the thread-disk system. The high-speed rotation of the rotors enables a pulsed high current, which holds great promise for potential applications in, for instance, generating electricity and harvesting energy from ocean waves and other rhythmic translational motions.

Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review.

One of the critical issues in orthopaedic regenerative medicine is the design of bone scaffolds and implants that replicate the biomechanical properties of the host bones. Porous metals have found themselves to be suitable candidates for repairing or replacing the damaged bones since their stiffness and porosity can be adjusted on demands. Another advantage of porous metals lies in their open space for the in-growth of bone tissue, hence accelerating the osseointegration process. The fabrication of porous metals has been extensively explored over decades, however only limited controls over the internal architecture can be achieved by the conventional processes. Recent advances in additive manufacturing have provided unprecedented opportunities for producing complex structures to meet the increasing demands for implants with customized mechanical performance. At the same time, topology optimization techniques have been developed to enable the internal architecture of porous metals to be designed to achieve specified mechanical properties at will. Thus implants designed via the topology optimization approach and produced by additive manufacturing are of great interest. This paper reviews the state-of-the-art of topological design and manufacturing processes of various types of porous metals, in particular for titanium alloys, biodegradable metals and shape memory alloys. This review also identifies the limitations of current techniques and addresses the directions for future investigations.

Examination of surface conditions and other physical properties of commonly used stainless steel acupuncture needles.

OBJECTIVES: The present work examined the surface conditions and various other physical properties of sterilised single-use stainless steel acupuncture needles from two of the most popular brands widely used in many countries. METHODS: Scanning electron microscope (SEM) images were taken for 10 randomly chosen needles from each brand. Further SEM images were taken after each of these needles underwent a standard manipulation with an acupuncture needling practice gel. A comparison of forces and torques during the needling process was also carried out. RESULTS: The SEM images revealed significant surface irregularities and inconsistencies at the needle tips, especially for needles from one of the two brands. Metallic lumps and small, loosely attached pieces of material were observed on the surfaces of some needles. Some of the lumps and pieces of material seen on the needle surfaces disappeared after the acupuncture manipulation. If these needles had been used on patients, the metallic lumps and small pieces of material could have been deposited in human tissues, which could have caused adverse events such as dermatitis. Malformed needle tips might also cause other adverse effects including bleeding, haematoma/bruising, or strong pain during needling. An off-centre needle tip could result in the needle altering its direction during insertion and consequently failing to reach the intended acupuncture point or damaging adjacent tissues. CONCLUSIONS: These findings highlight the need for improved quality control of acupuncture needles, with a view to further enhancing the safety and comfort of acupuncture users.