Methods for medical applications

Neuroendoscopy treats intracranial pathologies through millimeter-scale channels using endoscopes introduced along a straight trajectory from a cranial entry point to the target. The entry point acts as a Remote Center of Motion (RCM), which must remain fixed to follow the surgical plan and avoid damage around the entry point. Existing robotic RCM platforms rely on rigid multi-link structures, increasing complexity and footprint. To mitigate these limitations, we propose a compact dual-joint compliant mechanism for neuroendoscopic manipulation. Building on the Tetra II flexure architecture, we redesigned and optimized the joint for neurosurgical use. The end-effector holder is moved from the central axis to the side to improve visual access, facilitate sterile draping and allow rapid instrument exchange while preserving the RCM constraint. The mechanical design targets directionally uniform stiffness in the working plane while minimizing parasitic RCM displacements. The mechanism uses two identical compliant joints in series, with the connection angle treated as a design variable. For each angle, the response is obtained by analyzing each joint separately in FEM and combining their contributions via rotation matrices. An angular offset of 300° yields near-isotropic stiffness, with a root-mean-square error of 0.90 N/m from an ideal isotropic behavior. A PA12 prototype was tested under 0.1±0.01 N radial loads. Experimental stiffness differed by ≤19% from FEM. The parasitic RCM displacement was 0.032 ± 0.018 mm for a 4.5°shaft rotation, well within the 1 mm neurosurgical tolerance. This dual-joint compliant RCM mechanism offers a practical alternative to conventional rigid-link designs.

Keywords: Compliant joint , Finite element methods , Minimally invasive surgery , Remote Center of Motion

This paper explores the design, physical prototyping, and mechanical characterization of a haptic feedback system to be implemented in the simulation of Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) surgery. This technique is performed in extreme emergency situations, whereby it is hard to organize training on the patient under risk-free and controlled conditions. This constitutes the strong motivation for the realization of a simulator. The haptic feedback system consists of two different devices, each developed from an original concept and equipped with specific functions: a “push” device to simulate the axial force exerted on the catheter and perceived through haptic feedback by the surgeon; and a “torque” device to tighten or release the catheter when necessary, transferring torque resistance to the surgeon. After an in-depth analysis of the state of the art, the design is carried out with the aid of CAD and CAE software. The main components are manufactured through rapid prototyping techniques. The prototypes are tested qualitatively and quantitatively, proving their correct functionality in exerting sufficient force feedback.

Keywords: Catheter , Haptic device , Medical simulation

Many engineering applications require a constant operating force to safely interact with specific objects and prevent damage or destruction. This paper presents a compact constant-force mechanism (CFM) based on a novel architecture. The proposed design leverages the stiffness combination principle, integrating a negative-stiffness mechanism with a positive-stiffness element to achieve a near-constant force output. The negative stiffness is provided by a V-shaped bistable beam arranged in a parallel configuration, while the positive stiffness is contributed by a nested spring-like beam. As a fully compliant system, the mechanism benefits from advantages such as frictionless motion, cost-effectiveness, high precision, and scalability. These features make it well-suited for applications in soft robotic end-effectors, micro-electro-mechanical systems (MEMS), surgical tools, and biomedical devices. Finite element analysis (FEA) was employed for modeling, design, and validation of the mechanism's performance.

Keywords: Constant-Force Mechanism , Finite Element-based Design , Stiffness combination

In rehabilitation, the proper use of robotic devices offers significant advantages in both safety and treatment effectiveness. Correct use specifically includes accurate positioning of the user on the device to prevent misalignments that could result in discomfort or pain, and isolation of the movement to the intended body segment to avoid compensation strategies with other joints. This paper presents the design and development of an innovative wrist alignment and locking system implemented on the EDUSA® PRO robotic rehabilitation device. The proposed mechanism enables automatic centering of the human joint, aligning the user's axes with those of the robot, and securely maintains the wrist position throughout the rehabilitation session. Additionally, it automatically adapts to different wrist sizes and user anthropometric characteristics, making it suitable for a wider range of individuals. The ergonomic design ensures comfort, ease of use, and safety, while the modularity of the system allows for application to other joints. These features help reduce setting errors by therapists and contribute to greater effectiveness and reliability of the rehabilitation process.

Keywords: Product Design , Rehabilitation Robotics , Self-Centering Mechanism

We present a novel testing platform designed to characterize the mechanical performance of a flexible prosthetic wrist based on handed-shearing auxetic (HSA) structures. The platform is modular and supports both passive loading tests and active drive tests. An inertial measurement unit (IMU) and an integrated load cell are used to record the wrist's motion trajectory and the applied force under controlled conditions. We describe the system design, including a configurable base, interchangeable drive modules, and the control architecture. Experimental results demonstrate the platform's stability under significant loads (up to ∼23 N) and reveal a near-linear force–displacement relationship, indicating both robust performance and the feasibility of compensating for platform compliance.

Keywords: Flexible prosthetic wrist , Handed-shearing auxetic actuator , Load measurement , Mechanical compliance , Testing platform

This paper explores the application of a novel ring screw mechanism as a high-performance alternative to traditional rotary-to-linear motion converters in robotics. The ring screw's design, based on a theoretically ideal rolling motion between the moving parts, allows for significantly higher rotational speeds than ball screws. The work details the ring screw's implementation in two distinct robotic systems. First, it presents Skippy, a balancing and hopping monopedal robot, where the ring screw actuates the knee joint, enabling both precise balancing and dynamic hopping motions. Second, it introduces the FleXoWrist, a wearable exoskeleton designed to assist manual material handling by enhancing grasping capabilities. This paper demonstrates the successful application of the ring screw in both a legged robot and a wearable assistive device, showcasing its potential to enhance robotic actuation across diverse applications.

Keywords: Dynamic motion , Exoskeleton , Linear actuation

Purpose: This mini-review provides an updated overview of SPECT-based radiomics in oncology, summarizing clinical applications, highlighting SPECT-specific technical considerations, and identifying priorities for future research. Methods: A structured search of MEDLINE and Scopus was performed using the terms “SPECT,” “radiomics,” and “oncology.” Only original clinical studies published in English within the last five years were included. Eligible articles were screened and grouped by oncologic topic. Results: Eleven studies met the inclusion criteria. The reported applications included differentiation of metastatic versus benign bone lesions using bone SPECT/CT, prediction of survival in neuroblastoma with 123I-mIBG SPECT/CT, and characterization of indeterminate renal masses with 99mTc-sestamibi. Early work in radiodosiomics showed potential for estimating absorbed doses during peptide receptor radionuclide therapy and predicting response to selective internal radiation therapy. Conclusions: SPECT radiomics and radiodosiomics show promise for quantitative oncologic imaging, but the evidence base remains limited by small, retrospective, single-center studies and the complete absence of external validation. Standardizing acquisition and reconstruction protocols, and multicenter studies are essential to enable translation of SPECT-based radiomics into routine clinical practice.

Keywords: Oncologic imaging , Quantitative imaging , Radiodosiomics , Radiomics , SPECT , SPECT/CT , Texture analysis

Purpose: To assess machine learning (ML) classifiers trained on harmonised multicentre ¹²³I-mIBG planar scintigraphy for differentiating Parkinson's disease (PD) from non-PD parkinsonian syndromes and to determine whether early imaging alone may ensure accurate discrimination. Methods: This retrospective study included patients with suspected PD who underwent early (~ 15 min) and delayed (~ 240 min) imaging and received a definitive diagnosis after ≥ 12 months. Harmonised region of interest (ROI) placement and ComBat correction were applied. Early and late heart-to-mediastinum (H/M) ratios and washout rate (WR) were calculated. Differences were tested by Mann-Whitney U test, and cut-points identified by ROC analysis. Logistic regression, Gaussian naïve Bayes, and support vector machine were trained on these features with Z-score normalisation and synthetic minority oversampling technique (SMOTE). Results: 127 patients were analysed (85 PD, 42 non-PD). Early and late H/M ratios were significantly lower in PD than non-PD (early H/M 1.45 ± 0.20 vs. 1.80 ± 0.20; late H/M 1.33 ± 0.22 vs. 1.68 ± 0.21; both p < 0.001). WR was modestly higher in PD (8.74 ± 5.76% vs. 6.49 ± 6.19%, p = 0.024). Optimal cut-points for PD were: early H/M ≤ 1.62 (accuracy 80.3%, sensitivity 83.3%, specificity 78.8%, and AUC 0.878), late H/M ≤ 1.52 (83.5%, 83.3%, 83.5% and 0.866) and WR ≥ 6.03% (70.1%, 70.6%, 69.0% and 0.645). ML achieved mean accuracy 78.9–80.7%, sensitivity 81.9–84.0%, specificity 68.6–78.0%, and AUC 0.850–0.875. Conclusion: Classifiers trained on ¹²³I-mIBG semi-quantitative indices accurately distinguished PD from non-PD. Early H/M ratio alone provided excellent discrimination, supporting early-imaging; prospective validation is warranted.

Keywords: Artificial intelligence , Cardiac sympathetic denervation , ComBat harmonisation , Diagnostic accuracy , Heart-to-mediastinum ratio , Machine learning , Multicentre harmonisation , Parkinson's disease , ¹²³I-mIBG scintigraphy

Temporomandibular joint (TMJ) prostheses aim to restore joint function in cases of severe dysfunction or anatomical loss. This study presents a subject-specific design methodology using an integrated CAD and multibody (MB) approach to evaluate and optimize TMJ prosthesis performance. Experimental mandibular motion was captured using an optical tracking system and applied to a MB model replicating the subject's anatomy. Three prosthesis designs were assessed: an existing design provided by a company (CD), a revised new design (ND) and a digged design (DD) created through contact-driven surface modification. Performance metrics included interincisal distance at mouth complete aperture, condyle displacement and TMJ contact forces. The CD exhibited premature condyle dislocation and limited mobility. The ND introduced anatomical stops and surface inclination, significantly improving range of motion and reducing asymmetry. The DD further enhanced performance through optimized articular surface shaping, achieving near-physiological kinematics and a 35.7% reduction in peak contact force compared to CD. Results suggest that prosthetic performance can be substantially improved by tailoring articular geometries to subject-specific motion data. Future work will extend the model to include musculature for more comprehensive biomechanical analysis.

Keywords: Mobility , Multibody Model , Reaction Forces , Stability , TMJ Design

Additive Manufacturing (AM) displays unique capabilities in terms of fabricating parts including unconventional geometries. Much research is conducted to investigate the performances of AM from both the mechanical and the quality viewpoint. This research is aimed to complete the transition of AM from a rapid prototyping technology to a mature manufacturing option. Interestingly, this research is routinely conducted on standard geometries instead of those kind of topologies for which AM is an advantageous fabrication system. The study presented here originally compares the accuracy of AM for standard and complex shapes. As a case study, we used the model of a leg of a quadruped robot obtained with generative design in previous research. The model includes standard and non-standard geometries, with the latter being predominant. Ten copies of this model have been produced by AM, specifically by means of a 3D printer working with Fused Deposition Modelling. Two different orientations have been used for the model (five copies each). The 3D-printed physical models have been 3D-scanned and compared with the reference CAD model, which has allowed us to evidence deviations. The deviations have been displayed by using both global and local best-fit options in a quality assessment software application. The first analysis of achieved data suggests that printing parameters and the position of surfaces affect the accuracy of AM more than the characterization of surfaces as standard and non-standard.

Keywords: Additive Manufacturing , Deviations , freeform , Generative Design

Global demographic shifts, particularly the growing elderly population and their need for chronic disease management are straining healthcare systems. Innovative models that emphasize telemedicine and digitalization offer promising solutions to improve care and reduce costs. To evaluate the feasibility and sustainability of such a model, an adaptive mixed-methods approach, including dynamic context monitoring and a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis, was employed. A preliminary three-month regional study aimed to prevent acute events in older adults and enhance the quality of life using digital devices for self-monitoring vital signs was conducted. These data were transmitted in real-time to a platform monitored by general practitioners. Despite the short experimental period, early findings are promising, indicating the model's potential for scalability and adaptability to various settings, such as protected discharge or chronic care programs. However, addressing challenges like internet connectivity, healthcare professional engagement, sociocultural resistance, and the need for ongoing training is crucial. Effectively managing these factors while leveraging existing strengths and opportunities could lead to more efficient, responsive healthcare systems.

Keywords: Healthcare , Healthy and Active Ageing , Older adults , Sustainability , Telemedicine

Featured Application: The methodology presented in this work enables the direct extrusion-based 3D printing of soft, low-hardness RTV-2 silicone elastomers using industrial additive manufacturing systems. By adapting commercially available general-purpose silicones through viscosity tuning, the proposed approach expands the material palette for silicone additive manufacturing beyond proprietary formulations. This capability is particularly relevant for applications requiring highly compliant, biocompatible, and geometrically complex parts, such as soft robotics components, customized prosthetic and orthotic devices, medical simulation models, wearable interfaces, and flexible seals or gaskets. A particularly relevant industrial scenario for the proposed methodology is the small- to medium-batch production of customized silicone components, where traditional mold-based casting becomes economically inefficient due to tooling costs and long lead times. This study investigates the relationship between viscosity and manufacturability of two-component silicones in extrusion-based additive manufacturing. A methodology is proposed to adapt commercially available, low-viscosity general-purpose silicones for direct 3D printing using the material extrusion system provided by Lynxter S300X. EcoFlex™ 00-50 silicone was modified through controlled additions of a thixotropic agent (THI-VEX), producing formulations with progressively increased viscosity. After a preliminary qualitative viscosity assessment, formulations were printed using identical process parameters and evaluated through a set of dedicated geometric benchmark specimens targeting critical failure modes, including unsupported thin walls, overhangs, gaps, and slender structures. Print outcomes were assessed via multi-rater visual inspection with inter-rater reliability analysis to ensure consistency. Results reveal a strong correlation between thixotropy and geometric fidelity, identifying the formulation containing 4.0 wt% THI-VEX as optimal under the tested conditions. The study provides practical design and process guidelines for silicone additive manufacturing and highlights the importance of integrated material–process optimization for reliable fabrication of soft, highly deformable materials.

Keywords: geometric printability , material extrusion , RTV-2 silicone elastomers

This paper presents a comprehensive application of an automated surgical planning workflow for bone tumor resection, integrating two previously developed algorithms into a real clinical case. The study focuses on a patient with a left tibial osteosarcoma, demonstrating how the automated framework streamlines the entire preoperative process, from tumor resection planning to allograft selection. The cutting plane optimization tool reduced manual planning time from hours to just 19 min while ensuring complete tumor removal with minimal healthy bone resection. For reconstruction, the system automatically reconstructed the patient's premorbid anatomy and selected the best-matched allograft from a virtual donor database, achieving a high degree of anatomical precision (mean distance: 0.29 mm). The results highlight the clinical potential of this integrated approach, which improves efficiency, reduces subjectivity, and enhances reproducibility in complex bone tumor surgeries.

Keywords: Allograft , Design Method , Optimization , PSO , Tumor Resection , Virtual Prototyping

Wrist impairments are common in post-stroke and elderly populations, often requiring rehabilitation to restore joint mobility and strength. However, clinic-based programs pose accessibility challenges, especially for patients with limited mobility. This paper presents W.R.I.S.T. (Wrist Rehabilitation Intelligent Support Tool), a soft robotic prototype designed to facilitate wrist flexion-extension exercises in home settings. The system features an inflatable silicone handle integrated into a 3D-printed structure, equipped with a flexion sensor for monitoring and a pneumatic circuit for real-time resistance modulation. A microcontroller manages pressure regulation and sensor data acquisition, enabling adaptive therapies and personalized training. Experimental validation confirmed a predominantly linear relationship (R2 > 0.85) between sensor output and flexion angle across pressure levels, ensuring reliable motion tracking. Additionally, a game-based interface was developed to enhance user engagement, transforming repetitive exercises into an interactive task with customizable difficulty. The integration of adjustable mechanical resistance and interactive feedback supports progressive rehabilitation while promoting adherence. W.R.I.S.T. offers an affordable, customizable, and valid solution for decentralized rehabilitation, particularly suitable for elderly users or those with limited access to clinical services.

Keywords: 3D printing , Pneumatic , Rehabilitation , Soft Material , Wrist

Viscoelastic polymers are increasingly employed in lattice structures for their absorption and damping capabilities, particularly in applications involving vibration suppression or impacts. These structures exhibit remarkable properties, such as high specific stiffness, specific strength and energy absorption capacity, making them highly attractive for applications in aerospace, automotive, and biomedical fields. However, the accurate modeling by taking into account frequency-dependent behavior, especially for applications involving damping, remains challenging due to the interplay between geometric complexity and material viscoelasticity. To address this challenge, this study makes use of a general numerical homogenisation method enhanced for frequency-dependent material properties in order to predict the damping of the lattice structure at the macroscopic scale. A fractional derivative constitutive model is used to describe the frequency-depend behaviour of the bulk material, while a custom Ansys APDL code is developed to adapt the homogenisation method to the case of material with frequency-dependent properties. The results demonstrate that, for lattice structures made of a single material phase, it is possible to perform the homogenisation process at an arbitrary frequency. The resulting stiffness tensor of the equivalent homogeneous anisotropic material that replaces the structure at the macroscopic scale varies with frequency according to the same law used for the bulk material at a lower scale. Furthermore, the results show that even if the stiffness tensor of the lattice structure at the upper scale exhibits elastic symmetry depending on the topology of the unit cell, the damping matrix at the upper scale is unaffected by the lattice topology.

Keywords: Homogeneization , Lattice structures

Mandibular and maxillary bone regeneration is a significant challenge in orthodontics and maxillofacial surgery, particularly in patients with bone atrophy or advanced periodontal diseases. This study presents an innovative approach that integrates advanced imaging and manufacturing technologies to design and fabricate customized scaffolds based on data obtained through Cone Beam Computed Tomography (CBCT). The objective is to create biomimetic bone scaffolds suitable for infusion with autologous stem cells, promoting functional bone regeneration. The workflow comprises three key stages. CBCT images are processed to reconstruct detailed three-dimensional models of the mandibular or maxillary structure. Then, using generative optimization algorithms and surface subroutines in commercial CAD software, scaffolds are designed to replicate the mechanical, geometric, and biological properties of natural bone. The scaffolds are fabricated using 3D printing techniques with biocompatible and biodegradable materials. 3D printing enables high precision in creating porous structures optimized for vascularization, cellular integration, and mechanical support. This multidisciplinary approach, combining medical imaging, CAD/CAM design, and additive manufacturing, offers an advanced solution to address the challenges of bone regeneration in orthodontics. Preliminary results suggest that infusing scaffolds with stem cells could significantly accelerate bone regeneration and improve integration with surrounding tissues. Future studies will focus on preclinical validation of scaffolds.

Keywords: Biocompatible material , Biodegradable material , Bone scaffold , DICOM images , Mandibular and Maxillary Reconstruction

Lost-wax casting is an ancient technique of great precision, used for the creation of bronze artefacts. The artist makes the model in clay or plasticine and then creates the plaster or silicone mold. Inside the mould, wax is brushed to the ideal thickness of 5 to 6 mm and then wax “straws” were added at appropriate positions to allow optimal filling of the mould during bronze casting, starting with the lowest volumes. Finally, the wax model is incorporated into a refractory mass that surrounds it internally and externally and forms the cavity into which the bronze is poured. In this research, the results were obtained by analysing an innovative digital technique that avoids the creation of the mould and shrinkage during the intermediate stages of bronze production. In fact, using a 3D scanner and the latest rapid prototyping techniques, an accurate reproduction of the original clay model was recreated. The moulded model replaces the wax model. It is also enclosed between two forms of refractory material and, due to its similar melting temperature and flow properties, minimises build time and improves accuracy. The studied methodology also allows a more precise assignment and greater control of all surface thicknesses through a discretised digital finite element (FE) model analysis.

Keywords: Bronze sculptures' reconstruction , Laser scanning technology , Lost-wax bronze casting , Mold withdrawal , Rapid prototyping

Accurate three-dimensional (3D) reconstruction of individual dental elements from cone-beam computed tomography (CBCT) data is critical for adaptive prosthetic design and occlusal simulation in digital dentistry. However, challenges persist due to the complex morphology of teeth, the similar radiodensities of hard tissues, and the limited resolution of CBCT in capturing interproximal surfaces between adjacent teeth. This study presents a semi-automated, open-source compatible workflow that integrates CBCT image segmentation with the reconstruction of missing interproximal molar regions using Non-Uniform Rational B-Spline (NURBS) surface modeling. Molar datasets from CBCT acquisitions were segmented into 3D Slicer open-source software and refined to isolate individual teeth. Missing surface regions were reconstructed using third-degree NURBS patches in Rhinoceros® ver. 8 commercial software. Method reconstruction accuracy was quantitatively evaluated on 14 M by applying the method to manually created voids on intact tooth models. The average root-mean-square error (RMSE) and Hausdorff distance were 0.041 ± 0.015 mm and 0.049 ± 0.023 mm, respectively. The resulting models exhibited high surface continuity and anatomical fidelity, making them suitable for Computer Aided Engineering (CAE) analysis and prosthetic customization. This approach enables reproducible, high-precision dental modeling and represents a promising step toward fully automated 3D reconstruction workflows in clinical practice.

Keywords: CBCT segmentation , Digital prosthodontics , Molar morphology subdivision , NURBS modeling

Chewing simulators are essential tools in dentistry, as they enable the performance of innovative dental restorative materials to be analysed under realistic conditions. These devices replicate the complex movements and forces involved in mastication, enabling simulations of material wear and fatigue resistance. Their design and manufacture require a multidisciplinary approach that integrates mechanical engineering, materials science and dentistry, allowing the development of tools capable of improving the understanding of chewing processes and the effectiveness of dental treatments. This research focuses on a review of the main types of chewing articulators, highlighting the design and manufacturing aspects necessary to analyse the wear and the fatigue resistance of restorative materials. Construction characteristics, technologies employed and the most effective configurations for simulating realistic intra-oral conditions, including cyclic movements and variable forces, are highlighted. This study provides an overview of the main types of articulators currently in existence and their fabrication techniques, highlighting the importance of designing accurate, versatile, and increasingly reliable simulators. This allows to improve performance evaluation of dental materials while achieving greater success in patient-centred dental practices.

Keywords: Chewing articulators , Chewings' manufacture technique , Patient-centred treatment , Restorative material testing , Simulator design

This paper describes the design and preliminary testing of a soft exoskeleton for the shoulder which supports the adbuction/adduction movements. The soft exoskeleton is based on a single soft bellow actuator, a pneumatically actuated system which is composed by multiple consecutive chambers that expands when compressed air is inflated till providing a desired motion. In this work we present the design, analysis, prototyping and testing of the soft bellow actuator as well as its preliminary integration into a first version of bellow-based soft exoskeleton for the shoulder.

Keywords: Soft actuators , Soft exoskeletons , Soft robotics