Bioengineering

This study describes the developed special prototype of a wearable measuring device based on a photoplethysmography (PPG) sensor. It contains also a humidity sensor and a thermometer to measure skin moisture and temperature, and a force-sensitive (FSR) element to sense a contact pressure between the measuring probe and the skin surface. All parts of the multi-sensor are shielded, to be applicable in a weak magnetic field environment. After the basic sensor’s functionality verification inside the magnetic resonance imaging tomograph, a set of experiments was performed. Comparative measurements by an oximeter confirm good correspondence with heart rate values determined from PPG (HR_PPG) and FSR (HR_FSR) signals—the mean absolute error lies below 0.5 min⁻¹ for both types. The sensing of PPG signals on wrists was realized for Normal, Dry, and Wet skin. In comparison with normal skin conditions, drying decreases the PPG signal range by 7% and the systolic pulse width by 8%, while moistening increases the signal ripple by 3% and decreases the correlation between HR_PPG and HR_FSR values by 5%. The detailed analysis per hand and gender types yields differences between male and female subjects, while the results for left and right hands differ less.

Chronic pain management increasingly seeks objective biomarkers to complement subjective assessments. Ultra-weak photon emission (UPE), measurable via gas discharge visualization (GDV), has been proposed as a potential biomarker for various health conditions. However, the specificity of UPE measurements for pain versus comorbid conditions remains unexplored. This prospective cohort study followed 200 adults with electrodiagnostically confirmed neuropathic pain receiving cannabis therapy for 48 months. Assessments included the Numerical Rating Scale (NRS) for pain, Generalized Anxiety Disorder-7 (GAD-7) for anxiety, and Biowell UPE measurements. Cannabis therapy yielded 91.5% clinical response rate. However, UPE measurements showed striking differential validity: Biowell stress correlated strongly with GAD-7 (r = 0.579, p < 0.001) but negligibly with NRS (r = 0.093, p = 0.001), representing a 6.2-fold difference. Variance explained was 33.5% for anxiety versus 0.9% for pain. ROC analysis revealed good discrimination for clinical anxiety (AUC = 0.744) but poor discrimination for pain (AUC = 0.550). Mixed-effects modeling confirmed UPE stress predicted GAD-7 (b = 1.82, p < 0.001) but not NRS (b = −0.03, p = 0.84). These findings demonstrate that Biowell UPE measurements specifically capture psychological stress rather than nociceptive processes, with important implications for biomarker development in pain medicine. This study emphasizes the critical importance of validating proposed biomarkers against multiple related outcomes to establish specificity and appropriate clinical applications.

This study examines the impact of vocal fold (VF) lesions located on the superior surface on glottal airflow dynamics and tissue oscillatory behaviors using biomechanical simulations of a two-layered realistic VF model. It is hypothesized that morphological changes in the VFs due to the presence of a lesion cause changes in tissue elasticity and rheological properties, contributing to dysphonia. Previous research has lacked the integration of lesions in computational simulations of anatomically accurate larynx-VF models to explore their effects on phonation and contribution to voice disorders. Addressing the current gap in literature, this paper considers a computational model of a two-layered VF structure incorporating a lesion that represents a hemorrhagic polyp. A three-dimensional, subject-specific, multilayered geometry of VFs is constructed based on STL files derived from a human larynx CT scan, and a fluid–structure interaction (FSI) methodology is employed to simulate the coupling of glottal airflow and VF tissue dynamics. To evaluate the effects of the lesion’s presence, two FSI models, one with a lesion embedded in the cover layer and one without, are simulated and compared. Analysis of airflow dynamics and tissue vibrational patterns between these two models is used to determine the impact of the lesion on the biomechanical characteristics of phonation. The polyp is found to slightly increase airflow resistance through the glottis and disrupt vibratory symmetry by decreasing the vibration frequency of the affected fold, leading to weaker and less rhythmic oscillations. The results also indicate that the lesion increases tissue stress in the affected fold, which agrees with clinical observations. While quantitative ranges depend on lesion size and tissue properties, these consistent and physically meaningful trends highlight the biomechanical mechanisms by which lesions influence phonation.