Hyperelastic Properties of Platinum Cured Silicones and its Applications in Active Compression

Designing Biomimetic 3D-Printed Osteochondral Scaffolds for Enhanced Load-Bearing Capacity

Osteoarthritis is a debilitating chronic joint disorder that affects millions of people worldwide. Since palliative and surgical treatments cannot completely regenerate hyaline cartilage within the articulating joint, osteochondral (OC) tissue engineering has been explored to heal OC defects. Utilizing computational simulations and three-dimensional (3D) printing, we aimed to build rationale around fabricating OC scaffolds with enhanced biomechanics. First, computational simulations revealed that interfacial fibrils within a bilayer alter OC scaffold deformation patterns by redirecting load-induced stresses toward the top of the cartilage layer. Principal component analysis revealed that scaffolds with 800 μm long fibrils (scaffolds 8A-8H) possessed optimal biomechanical properties to withstand compression and shear forces. While compression testing indicated that OC scaffolds with 800 μm fibrils did not have greater compressive moduli than other scaffolds, interfacial shear tests indicated that scaffold 8H possessed the greatest shear strength. Lastly, failure analysis demonstrated that yielding or buckling models describe interfacial fibril failure depending on fibril slenderness S. Specifically for scaffolds with packing density n = 6 and n = 8, the yielding failure model fits experimental loads with S < 10, while the buckling model fitted scaffolds with S < 10 slenderness. The research presented provides critical insights into designing 3D printed interfacial scaffolds with refined biomechanics toward improving OC tissue engineering outcomes.

Silicone Elastomeric-Based Materials of Soft Pneumatic Actuator for Lower-Limb Rehabilitation: Finite Element Modelling and Prototype Experimental Validation

This study describes the basic design, material selection, fabrication, and evaluation of soft pneumatic actuators (SPA) for lower-limb rehabilitation compression therapy. SPAs can be a promising technology in proactive pressure delivery, with a wide range of dosages for treating venous-related diseases. However, the most effective design and material selection of SPAs for dynamic pressure delivery have not been fully explored. Therefore, a SPA chamber with two elastomeric layers was developed for this study, with single-side inflation. The 3D deformation profiles of the SPA chamber using three different elastomeric rubbers were analyzed using the finite element method (FEM). The best SPA-compliant behavior was displayed by food-grade silicone A10 Shore with a maximum deformation value of 25.34 mm. Next, the SPA chamber was fabricated using A10 Shore silicone and experimentally validated. During the simulation in FEM, the air pressure was applied on the inner wall of the chamber (i.e., the affected area). This is to ensure the applied pressure was evenly distributed in the inner wall while the outer wall of the chamber remained undeformed for all compression levels. During the inflation process, pressure will be applied to the SPA chamber, causing exerted pressure on the skin which is then measured for comparison. The simulation and experimental results show an excellent agreement of pressure transmission on the skin for the pressure range of 0–120 mmHg, as depicted in the Bland–Altman plots. The findings exhibited promising results in the development of the SPA chamber using low-cost and biocompatible food-grade silicone.

Study of Three Interface Pressure Measurement Systems Used in the Treatment of Venous Disease

The aim of the publication is to report the accuracy, repeatability and the linearity of three commercially available interface pressure measurement systems employed in the treatment of venous disease. The advances in the treatment and management of chronic venous disease by compression therapy have led to considerable research interest in interface pressure measurement systems capable of measuring low-pressure ranges (10-60 mmHg). The application of a graduated pressure profile is key for the treatment of chronic venous disease which is achieved by using compression bandages or stockings; the required pressure profiles are defined in standards (BSI, RAL-GZ, or AFNOR) for different conditions. However, achieving the recommended pressure levels and its accuracy is still deemed to be a challenge. Thus, it is vital to choose a suitable pressure measurement system with high accuracy of interface pressure. The authors investigated the sensing performance of three commercially available different pressure sensors: two pneumatic based (AMI and PicoPress®) and one piezoresistive (FlexiForce®) pressure sensors, with extensive experimental work on their performance in terms of linearity, repeatability, and accuracy. Both pneumatic based pressure measurement systems have shown higher accuracy in comparison to the flexible piezoresistive pressure sensors.