Electric wheelchairs make it easier for disabled and elderly people to live, move, interact, and participate in society. Moving a wheelchair in open spaces is relatively easy, but in closed and small spaces, maneuvering is difficult. Solutions to such problems for people with disabilities are applicable to a relatively small group of recipients and are mostly custom-made solutions, whose considerable cost is a significant barrier to accessibility. New technologies can provide an opportunity to improve the quality of life of people with disabilities in this aspect. Using selected elements of complex automation and control systems, cost-effective solutions can be created that facilitate the functioning of people with disabilities. This paper presents an analysis of hazards and problems when maneuvering a wheelchair in narrow passageways, as well as the authors’ solution to this problem, and the concept and assumptions of a mechatronic anti-collision system based on 2D LiDAR laser scanners. This solution is composed of a proprietary 2D rotating scanner mechanism that ensures the acquisition of 3D images of the environment around the wheelchair. Preliminary tests of this solution yielded promising results. Further research will include miniaturization of the device.

This study investigates the influence of different finite element material modeling approaches on the mechanical response of a femoral bone segment under three-point bending. Four material variants, ranging from homogeneous isotropic to heteroge-neous isotropic models, were analyzed to assess their impact on displacement and stress distribution. Results demonstrate that material heterogeneity significantly af-fects displacement magnitudes, with homogeneous models underestimating defor-mation compared to heterogeneous ones that more realistically represent cortical and cancellous bone properties. Stress distribution patterns were primarily governed by geometry and boundary conditions, though stress concentrations near supports were identified as potential numerical artifacts. These findings underscore the importance of incorporating bone heterogeneity and anisotropy in FEM for accurate biomechan-ical simulations. Future research should focus on advanced anisotropic modeling, nonlinear behavior, and physiologically relevant loading conditions to enhance pre-dictive capabilities, particularly for clinical applications such as implant design and surgical planning.

Polymer insert is one of the components of a knee joint endoprosthesis, allowing patients to sustain their mobility. They are mostly made of ultra-high molecular weight polyethylene (UHMWPE) that is not without flaws. Inserts can be manufactured by machining (substractive techniques) or by the use of rapid prototyping techniques (additive manufacturing). In order to increase their strength, is increasingly being considered replacing UHMWPE with polyether ether ketone (PEEK). This material has been analyzed in this work due to the growing interest in using this material for the production of implants. This study contains a comparative analysis of two inserts made using two different methods. Its aim is to verify the effect of the manufacturing technique on material uniformity.

The purpose of this study was to examine the accuracy of HR measurements by the PTN-104 sensor in comparison to the fingertip pulse oximeter, which is a photoplethysmographic sensor (PPG). Twelve healthy participants underwent the same protocol during a single visit. Measurements were taken after each participant completed an initial rest period of 5 minutes and after 1-minute of exercising comprising of 30 squats. Each subject had the PTN-104 sensor attached to the index finger and a fingertip pulse oximeter to the opposite one. When examining the data in aggregate, there was a strong correlation between the PTN-104 sensor and PPG for HR (r = 0.988) with a mean bias of −2.55 bpm (95 % LoA +5.0, −10.1). The PTN-104 sensor satisfied validity criteria for HR monitors, however, showed a lower accuracy for measurements at rest, which is surprising. Due to the noticed limitations, this study should be repeated with a larger group of subjects and the PTN-104 sensor should be compared to the gold standard method for measuring HR, which is ECG.

Dynamic mechanical analysis is widely used to characterize viscoelastic materials, yet the physical origin of the measured phase shift remains only partially understood for structurally extended specimens. Its standard interpretation typically assumes a single, effective phase shift between applied stress and strain. In this work, we investigate the temperature-dependent viscoelastic response of medical- grade acrylonitrile butadiene styrene (ABS) fabricated by fused filament fabrication and injection molding, combining DMA measurements, fractographic analysis, and analytical modeling. Rectangular beam specimens were subjected to three-point bending DMA over a tempera- ture range spanning the glass transition region. The storage modulus, loss modulus, and phase shift were determined as functions of tem- perature and compared between manufacturing routes. While both materials exhibit nearly identical glass transition temperatures, the 3D- printed samples exhibit a modest reduction in storage modulus, reflecting microstructural heterogeneity introduced by the layer-wise fabri- cation process. Fractographic observations reveal characteristic interlayer features and microvoids that correlate with the observed mechan- ical response. To interpret the temperature-dependent phase shift, we develop a theoretical model of a damped vibrating beam in which each eigenmode contributes with its own phase shift. By introducing a temperature-dependent effective damping coefficient, the model’s mode-averaged phase shift reproduces the experimental DMA data with high accuracy. By linking DMA phase measurements to the mode dynamics of the tested structure, the proposed framework establishes DMA as a structure-sensitive dynamical probe and is applicable to a broad class of polymer, composite, and additively manufactured materials.