Breastfeeding is essential for infant nutrition, but the increasing number of women returning to work before weaning highlights the need for efficient and comfortable milk expression methods. Traditional breast pumps rely solely on vacuum suction, which can cause discomfort, tissue damage, and longer extraction times compared to natural nursing. This study aims to develop a breast pump that better mimics the biomechanics of infant breastfeeding to improve comfort and efficiency. We investigated two actuator designs–membrane and soft pleated–integrated into the breast shield to replicate infant sucking. The pleated actuator proved most effective, offering a wide range of expansion and contraction. Unlike traditional pumps, vacuum is applied through radial expansion, allowing the nipple to widen rather than elongate, closely simulating infant tongue movements. The breast shield was fabricated using additive manufacturing with soft, elastic materials, enabling complex geometries and varied stiffness. The prototype was tested against a commercial pump using an artificial breast phantom. Results suggest this design can enhance milk output, reduce pumping time, and improve user comfort. By merging soft robotics with biological insights, our approach offers a promising alternative to conventional breast pumps.

Human fingers exhibit remarkable dexterity and adaptability through a combination of structures with varying stiffness levels, ranging from soft tissues (low stiffness) to tendons and cartilage (medium stiffness) to bones (high stiffness). This paper focuses on the development of a robotic finger that emulates these multi-stiffness characteristics. Specifically, we propose utilizing a lattice configuration, parameterized by voxel size and unit cell geometry, to achieve fine-tuned stiffness properties with high precision. A key advantage of this approach is its compatibility with single-process 3D printing, which eliminates the need for manual assembly of components with varying stiffness. Using this method, we present a novel, human-like robotic finger and a soft gripper. The gripper is integrated with a rigid manipulator and demonstrated in pick-and-place tasks, showcasing its effectiveness.

Metal additive manufacturing is a promising technology for the production of functional medical products, due to its high shape complexity and resolution, and ability to withstand sterilization temperatures. This study explores the possibility of designing a completely non-assembly steerable surgical instrument using Selective Laser Melting. Despite its advantages for medical devices, the rough surface quality of unfinished parts can be problematic for non-assembly designs, leading to increased friction and wear in rigid body mechanisms and tendon-actuated mechanisms. We investigated printing of rolling contact joints with crossed flexures as low-friction joints, adjusted for printing in titanium for the design of the instrument. Grid-based lattice structures were incorporated as miniature flexures, and we explored the influence of various grid sizes on the flexibility and bending stiffness of the lattices. Based on this exploration, we altered the rolling joint configuration from two crossed flexures to a single straight flexure for our design. The resulting steerable surgical instrument design is completely non-assembly, including its actuation, facilitates easy removal of support structures, and requires no surface finishing steps. It has a diameter of less than 20 mm, facilitates opening and closing of a grasper, and steering of the grasper by 20 degrees.

Parts produced with metal additive manufacturing often suffer from a poor surface finish. Surface finishing techniques are effective to improve the quality of 3D printed surfaces, however they have as downsides that they also slightly change the geometry of the part, in an unpredictable way. This effect on the geometrical features of complex parts has received little attention. In this research, we illustrate a method to visualize the impact of surface finishing techniques on geometrical features, as well as their effectiveness on parts with high shape-complexity, by using centrifugal disk finishing as a case study. We designed and 3D printed test parts with different features using selective laser melting, which were coated with a blue metal lacquer prior to polishing. After polishing, the blue lacquer was eroded away from the spots that were easily reached by the polishing process, yet had remained on the surfaces that could not be reached by the process. We used measurements of material removal and image processing of the remaining blue lacquer on the surfaces to analyze these effects. Using this method, we were able to derive a number of specific design guidelines that can be incorporated while designing metal AM parts for centrifugal disk finishing. We suggest that this visualization method can be applied to different polishing methods to gain insight into their influence, as well as being used as an aid in the design process.

Additive Manufacturing (AM) or 3D printing has enabled the production of increasingly complex parts that are difficult to produce with conventional manufacturing methods. Its additive nature has made it possible to create interlocking parts in a single production step. This creates opportunities for new ways of designing and producing mechanisms, which do not need to be assembled after production, called non-assembly mechanisms. Non-assembly mechanisms are different from traditional mechanisms, since they show an unprecedented integration between geometry, material and structure. In this review, by means of a systematic literature search the current state-of-the-art of non-assembly mechanisms is reviewed and analyzed based on the challenges encountered in their design and production. The found examples were categorized according to types of mechanism that have similar production considerations. Per category is discussed what the challenges and opportunities are for the design of non-assembly mechanisms. This review aims to provide a helpful overview of best-practice examples that can be used as inspiration for further development of innovative non-assembly mechanisms.