Anti-Adhesive Surfaces Inspired by Bee Mandible Surfaces.

Propolis, a naturally sticky substance used by bees to secure their hives and protect the colony from pathogens, presents a fascinating challenge. Despite its adhesive nature, honeybees adeptly handle propolis with their mandibles. Previous research has shown a combination of an anti-adhesive fluid layer and scale-like microstructures on the inner surface of bee mandibles. Our aim was to deepen our understanding of how surface energy and microstructure influence the reduction in adhesion for challenging substances like propolis. To achieve this, we devised surfaces inspired by the intricate microstructure of bee mandibles, employing diverse techniques including roughening steel surfaces, creating lacquer structures using Bénard cells, and moulding resin surfaces with hexagonal patterns. These approaches generated patterns that mimicked the bee mandible structure to varying degrees. Subsequently, we assessed the adhesion of propolis on these bioinspired structured substrates. Our findings revealed that on rough steel and resin surfaces structured with hexagonal dimples, propolis adhesion was significantly reduced by over 40% compared to unstructured control surfaces. However, in the case of the lacquer surface patterned with Bénard cells, we did not observe a significant reduction in adhesion.

Model-Based Biomechanical Exoskeleton Concept Optimization for a Representative Lifting Task in Logistics.

Occupational exoskeletons are a promising solution to prevent work-related musculoskeletal disorders (WMSDs). However, there are no established systems that support heavy lifting to shoulder height. Thus, this work presents a model-based analysis of heavy lifting activities and subsequent exoskeleton concept optimization. Six motion sequences were captured in the laboratory for three subjects and analyzed in multibody simulations with respect to muscle activities (MAs) and joint forces (JFs). The most strenuous sequence was selected and utilized in further simulations of a human model connected to 32 exoskeleton concept variants. Six simulated concepts were compared concerning occurring JFs and MAs as well as interaction loads in the exoskeleton arm interfaces. Symmetric uplifting of a 21 kg box from hip to shoulder height was identified as the most strenuous motion sequence with highly loaded arms, shoulders, and back. Six concept variants reduced mean JFs (spine: >70%, glenohumeral joint: >69%) and MAs (back: >63%, shoulder: >59% in five concepts). Parasitic loads in the arm bracing varied strongly among variants. An exoskeleton design was identified that effectively supports heavy lifting, combining high musculoskeletal relief and low parasitic loads. The applied workflow can help developers in the optimization of exoskeletons.

Interaction between honeybee mandibles and propolis.

In a biomimetic top-down process, challenging the problem of resin deposition on woodworking machine tools, an adequate biological model was sought, which hypothetically could have developed evolutionary anti-adhesive strategies. The honeybee (Apis mellifera) was identified as an analogue model since it collects and processes propolis, which largely consists of collected tree resin. Propolis is a sticky substance used by bees to seal their hive and protect the colony against pathogens. In spite of its stickiness, honeybees are able to handle and manipulate propolis with their mandibles. We wanted to know if beneficial anti-adhesive properties of bee mandibles reduce propolis adhesion. The anatomy of bee mandibles was studied in a (cryo-)scanning electron microscope. Adhesion experiments were performed with propolis on bee mandibles to find out if bee mandibles have anti-adhesive properties that enable bees to handle the sticky material. A scale-like pattern was found on the inside of the mandible. Fresh mandibles were covered with a seemingly fluid substance that was at least partially removed during the washing process. Propolis adhesion on bee mandibles was measured to be 1 J/m2 and was indeed significantly lower compared to five technical materials. Propolis adhesion was higher on mandibles that were washed compared to fresh, unwashed mandibles. Results indicate that the medial surface of the mandible is covered with a fluid substance that reduces propolis adhesion. First results suggested that the surface pattern does do not have a direct effect on propolis adhesion.

RapidNAM: Algorithm for the Semi-Automated Generation of Nasoalveolar Molding Device Designs for the Presurgical Treatment of Bilateral Cleft Lip and Palate.

OBJECTIVE: Nasoalveolar molding (NAM) is an accepted presurgical treatment modality for newborns with cleft lip and palate (CLP). However, the therapy is time-consuming and requires high expertise. To facilitate the treatment, we reveal an algorithm for the automated generation of patient individual NAM devices for neonates with bilateral cleft lip and palate (BCLP) and present results of software validation. METHODS: The algorithm was implemented utilizing Python 2.7 and Blender 2.78a based on 17 digitized (3D-scanning) impressions of maxillae with BCLP. The algorithm segments alveolar structures, bridges clefts, and generates a series of NAM device designs, destined for 3D-printing for subsequent treatment. The datasets were used for first software tests. For validation, a follow-up study was carried out using six new, independent maxilla models. The generated NAM plate designs were examined regarding their potential clinical usability. Furthermore, a deviation analysis was carried out, which measured the plate models' and upper jaw models' surface deviations. RESULTS: Series of NAM devices were generated automatically in 21 out of 23 cases. We calculated an average surface deviation of 0.140 mm (SD: 0.016 mm). Four out of six plate series (follow-up trials) were assessed as probably usable with minor adjustments. CONCLUSION: The algorithm generates 3D-printable series of NAM device designs reliably. We expect most of the series to be clinically usable and that the first plates of each series will fit the patients' maxillae. SIGNIFICANCE: The proposed algorithm has the potential to reduce the therapist's manual work and therefore time effort/costs related to NAM.