Novel insights into the design of stretchable electrical systems

Soft electronics have recently gathered considerable interest because of their biomechanical compatibility. An important feature of deformable conductors is their electrical response to strain. While development of stretchable materials with high gauge factors has attracted considerable attention, there is a growing need for stretchable conductors whose response to deformation can be accurately engineered to provide arbitrary resistance-strain relationships. Rare studies addressing this issue have focused on deterministic geometries of single rigid materials, limiting the scope of these strategies. We introduce the novel concept of periodic stretchable patterns combining multiple conductive materials to produce tailored responses. Using shortest path algorithms, we establish a computationally efficient selection method to obtain the required resistance-strain relationship. Using this algorithm, we identify and experimentally demonstrate constant resistance-strain responses up to 50% elongation using a single microtextured material. Last, we demonstrate counterintuitive sinusoidal responses by integrating three materials, with interesting applications in sensing and soft robotics.

Research on Biomechanical Compatibility for the Artificial Anal Sphincter Based on Improved Actuator

Anal incontinence, also known as fecal incontinence, refers to the loss of the body's ability to accumulate and control the liquid, solid, and gas contents in the rectum, increasing the frequency of bowel movements. It is a symptom of defecation disorders. The artificial anal sphincter provides a new solution for clinical treatment. In this paper, in order to solve the problem of biomechanical compatibility of the actuator of the artificial anal sphincter system, the original actuator was improved. The model of the rectum and the actuator was constructed by ANSYS. The mechanical finite element analysis of the clamping mechanism was carried out by simulating sphincter behavior, and the displacement cloud diagram and stress cloud diagram of the clamping rectum were obtained. in vitro experiments were carried out using pig intestine to simulate the rectum, which verified the effectiveness of the actuator. The results of the experiment show that the successful rate of holding the rectum reached 96% under the condition of ensuring the normal blood supply to the rectum. It fully proves that the actuator has good biomechanical compatibility.

Assessment of a novel artificial anal sphincter with constant force

Fecal incontinence caused by sphincter dysfunction is an unresolved problem which has a serious effect on patients, both physically and psychologically. For patients with severe symptoms, treatment with an artificial anal sphincter could be a potential option to restore continence. Acticon Neosphincter still has safety and efficacy problems, which is the only device certified by the US Food and Drug Administration. The biomechanical compatibility is the key problem of artificial anal sphincter in the clinical application. This paper describes an artificial anal sphincter with superelastic shape memory alloys and its mechanical properties assessment in artificial intestine models. The new design was developed as a low invasive and constant force or pressure prosthesis with a simple structure to solve the problem of severe fecal incontinence in patients.

First-generation total ankle arthroplasty

Ankle prostheses are a source of disagreement within the orthopedic community due to the poor initial results. The lack of alternatives to arthrodesis has promoted the evolution of arthroplasties. Biomechanical compatibility has been improved, new surgical techniques and instrumentation devices have been developed, and biological techniques for fixation of the various components have been introduced. The first-generation arthroplasty prostheses introduced in the 1970s were cemented and had a stable constrictive design, but because they required extensive bone resection for implantation, they failed due to loosening and extensive osteolysis. We report a case of left total ankle arthroplasty performed in 1980 that is still “in situ”. Based on the bibliographic research performed, this case seems to represent the longest-lasting implant reported to date. Level of Evidence V; Therapeutic Studies; Expert Opinion.

Numerical Analysis of a Dental Zirconium Restoration and the Stresses That Occur in Dental Tissues

When it is about restorative dental materials, aesthetics is traditionally preferred. This has led to the selection of materials very visually similar to the enamel, but unfortunately, their mechanical properties are not similar. This often translates into disadvantages than advantages. In the present work, a comparison is made of the stresses that occur during dental occlusion (dental bit) in a healthy dental organ and those that are generated in a dental organ with a dental zirconium restoration. Numerical simulation was carried out by means of the Finite Element Method, in computational biomodels, from Cone-Beam Tomography, to obtain the stresses generated during dental occlusion. It was found that the normal and von Mises stresses generated are substantially greater in the molar with restoration compared to those produced in the healthy molar. In addition, the normal function of the enamel and dentin to disperse these stresses to prevent them from reaching the pulp is altered. Therefore, it is necessary to analyze the indiscriminate use of this restoration material and consider other aspects, in addition to aesthetics and biocompatibility for the choice of restorative materials such as biomechanical compatibility.

Prediction of stress shielding around implant screws induced by three-point and four-point bending

Implant screws failure commonly occurs due to the load that constantly generated by the patient’s body to the fracture area. Bending load is often encountered in femur bone due to lateral impact which affected the bone and also the implants installed. Consequently, the load will lead to the failure of implants that can cause loosening or tightening of implants. Henceforth, in this manner, it is significant to study the bending behavior of bone implant in femur bone. The aim of this study was to analyze the stress shielding of bone implant on the internal fixator. 3D technique is able to show the overall deformation and stress distribution. The lower the biomechanical compatibility, the lower the STP value obtained. In addition, the variation of elastic modulus (E) of the screws materials, 200GPa (Stainless Steel) and 113.8GPa (Titanium) resulted in the increase of the total stress transferred (STP) between screw and bone interface. In this work, strain energy density (SED) was determined as a good indicator of stress shielding.