Search Results (108)

In therapeutic applications, ultrasound is widely used in physiotherapy, tissue repair, and cancer treatment. Regarding cancer treatment, as an emerging field for technology, significant research efforts have been devoted to the area of ultrasound therapy. The derived energy from beams can be deposited in tissues not only through heating but also through non-thermal mechanisms, whereby cancer cells are subject to cell death. Ultrasound-induced heating can generate localized temperature elevations within biological tissues, making it a subject of interest for thermal therapeutic applications. Nevertheless, excessive temperature elevations outside the primary exposure region may result in undesirable thermal effects within the surrounding tissue. In this study, we used continuous 3 MHz ultrasound waves at the powers of 0.4 to 1.4 W on ex vivo chicken breast tissue in a water bath to prevent fluctuations in temperature. The process was also numerically modeled with a maximum error of 0.4% from the measured data. Temperature measurements revealed a significant difference between the region of maximum acoustic pressure along the beam axis and deeper tissue locations (in some cases, above 3.5 °C). These findings indicate that temperature gradients can develop within homogeneous tissue during ultrasound exposure, emphasizing the importance of controlling acoustic power and exposure conditions. Moreover, increasing the temperature was significant during the first moments of treatment, which highlights the importance of precise controls for rate and precision in therapy. The numerical simulations also showed that increasing acoustic power elevates tissue temperature while simultaneously producing a less uniform temperature distribution. These observations may be useful for the optimization of future ultrasound-based thermal treatment strategies; however, direct clinical extrapolation requires further investigation using physiologically representative tissue models. Full article

This study presents a comprehensive computational evaluation of radiofrequency (RF) ablation efficacy and the spatial formation of thermal ablation zones within a 3D model of a liver tumor. By systematically comparing these configurations, the study aims to elucidate the physical mechanisms governing electromagnetic (EM) energy dissipation in hepatic tissue and to provide clear engineering guidelines for optimizing RF applicator selection and treatment planning in clinical practice. To reliably simulate the biophysical phenomena of the RF ablation procedure, a coupled electro-thermal model based on the finite element method and the Pennes bioheat equation was implemented. The research investigates six distinct applicator variants: conventional needle-type applicators and advanced expandable umbrella-type RF applicators equipped with four- and eight-tine electrodes, each evaluated in both monopolar and bipolar configurations. Numerical simulations were conducted for a standard 10 min ablation procedure at varying applied voltages to assess the specific absorption rate (SAR) distribution, transient heating dynamics, and the exact volumes of the resulting coagulation necrosis which were quantified using rigorous isotherms and the cumulative equivalent minutes at 43 °C (CEM₄₃) thermal dose index. Volumetric analysis of the ablation zones revealed that bipolar multi-tine electrodes induce highly localized heat concentration. Conversely, monopolar multi-tine setups strongly disperse EM energy. The results demonstrated that, for conventional needle applicators, the monopolar configuration generated significantly larger necrosis zones than the bipolar operating mode. The RF applicator geometry and its operating mode directly dictate the spatial extent of liver tissue necrosis. Moreover, advanced numerical treatment planning is essential for optimizing SAR and CEM₄₃ distributions and ensuring safe and complete hepatocellular carcinoma eradication. Full article

Thermal tactile perception plays a crucial role in enhancing realism and immersion in human–machine interaction, virtual/augmented reality, and wearable systems. By exploiting the thermoelectric effect to achieve precisely controllable heating and cooling, wearable thermoelectric devices (WTEDs) offer an effective approach for generating localized and programmable thermal sensations, which calls for a clear understanding of skin temperature regulation mechanisms. In this work, a dynamic thermal conduction model is developed for a skin–WTED integrated system incorporating a nickel foam-reinforced hydrogel heat sink, based on the dual-phase lag (DPL) bioheat conduction theory. The model accounts for blood perfusion and metabolic heat generation in skin tissue, as well as the Thomson effect within the thermoelectric legs and convective heat losses from their side surfaces. The theoretical predictions are validated through human skin temperature regulation experiments using a fabricated WTED, showing close agreement between experiments and simulations and confirming the model’s accuracy and reliability. Based on the validated model, the cooling current, filling factor, and thermoelectric leg height are optimized by minimizing the skin surface temperature. Furthermore, the model is applied to thermal tactile feedback studies, enabling the controlled reproduction of skin thermal sensations associated with common objects, including an iron block, a PMMA plate, and carbonated beverages packaged in aluminum cans and plastic bottles. Overall, this study provides a practical and predictive framework for understanding, optimizing, and applying WTEDs in thermal tactile feedback. Full article

The convergence of artificial intelligence, biotechnology, and the Internet of Bio-Nano Things (IoBNT) is enabling the creation of a new generation of intelligent in-body medical devices for continuous diagnosis and monitoring. In this context, a compact, wideband, circularly polarized conformal microstrip antenna is proposed for capsule endoscopy applications. The antenna is integrated along the inner wall of a 10 mm-diameter capsule and achieves an impedance bandwidth of 2.06–5.39 GHz (89.39%), maintaining stable matching under varying biological tissue conditions. A 3 dB axial ratio bandwidth (ARBW) of 2.31–3.14 GHz (30.45%) ensures reliable circular polarization and robust wireless communication in lossy and dynamic in-body environments. To extend beyond conventional electromagnetic analysis, a physics-informed neural network (PINN) framework is introduced to model the thermal response of biological tissues based on the governing bioheat equation. This AI-driven approach enables fast and generalizable prediction of temperature rise under varying operational conditions without repeated numerical simulations. At 2.45 GHz, the antenna exhibits a maximum gain of $-31.1$ dBi with a radiation efficiency of approximately $-34$ dB, consistent with in-body propagation constraints. Simulation and experimental results in realistic tissue phantoms, including muscle, small intestine, large intestine, and stomach, confirm stable wideband and polarization performance. Specific absorption rate (SAR) analysis demonstrates compliance with IEEE C95.1-2019 safety limits, while link budget evaluation validates reliable telemetry over a 1–3 m communication range. The integration of advanced antenna design with physics-informed machine learning provides a scalable framework for intelligent, safe, and adaptive IoBNT-enabled capsule endoscopy systems. Full article

The use of wood chips in the heating sector leads to the generation of combustion waste with variable properties, which poses challenges for their rational management. To determine the variability of combustion waste, samples were collected over a 13-week period during the heating season, as weekly aggregate samples from a biomass bioheating plant burning wood chips. Three waste fractions were obtained for analysis: residue from the grate (B1), dust from the dust collector (B2), and boiler dust (B3). Dry matter (DM), reaction (pH_KCl), electrolytic conductivity (EC), content of total carbon (TC), total nitrogen (TN), macronutrients (P, K, Mg, Ca, Na), and heavy metals (Fe, Mn, Zn, Cu, Pb, Cd, Cr, Co, Ni) were determined in the collected samples. All waste fractions were characterized by an alkaline reaction. Regardless of the waste fraction, the macronutrient content was dominated by Ca, K, and Mg, with significantly lower levels of P and Na. Among heavy metals, Fe, Mn, and Zn had the highest recorded contents, and the lowest by far was Cd. With respect to sampling dates, the least diversified chemical composition was observed for B1 samples, more diversified for B2, and the most diversified for B3. In turn, regardless of the waste fraction, the most diversified results were observed for Cd and Pb, and the least for pH, DM, and TC. Concerning environmental management of combustion waste, fraction B1 deserves attention, as it was characterized by the richest chemical composition (TN, P, K, Mg, Ca, Na, Mn, Zn, Cu, Co, Ni). However, due to the highest content of undesirable heavy metals (Pb, Cd) and the highest salinity, it requires constant monitoring of the composition. Full article

Electromagnetic field-based stimulation has emerged as a promising noninvasive approach for enhancing bone fracture healing. Beyond conventional pulsed electromagnetic field (PEMF) therapies employing spatially uniform fields, dielectrophoretic-force-based (DEPF) stimulation exploits electromagnetic field non-uniformities to induce localized interactions to enhance fracture healing. However, the thermal behavior associated with DEPF-driven PEMF exposure in the presence of metallic orthopedic implants remains largely unexplored. In this study, the thermal response of tissue-like tibia phantoms with and without metallic implants is investigated using an integrated experimental and numerical framework. A custom-designed conical coil is employed to generate non-uniform DEPF excitation capable of affecting the fracture site. Surface temperature evolution is measured using infrared thermal imaging, while electromagnetic power absorption is quantified through specific absorption rate (SAR)-based thermal measurement coupled with a bio-heat formulation. Anatomically realistic tibia phantoms reconstructed from computed tomography data are fabricated via a 3D printer to represent clinically relevant fracture configurations. Experimental results show that the metallic implant exhibits a rapid temperature increase of approximately $0.4 °\mathrm{C}$ within the first few minutes of exposure, followed by thermal stabilization, corresponding to an effective absorbed power of ${\mathrm{SAR}}_{\mathrm{eff},\mathrm{implant}}\approx 2.2 \mathrm{W}/\mathrm{kg}$ inferred from the initial temperature slope. In contrast, the non-conductive resin phantom displays a temperature rise of only $0.05 °\mathrm{C}$ over the same interval, yielding ${\mathrm{SAR}}_{\mathrm{eff},\mathrm{resin}}\approx 0.8 \mathrm{W}/\mathrm{kg}$. These findings demonstrate that implant-related eddy-current losses dominate localized heating under DEPF excitation, while tissue-like media remain weakly affected. This work provides SAR-based experimental evaluation of DEPF stimulation in implanted tibia fracture models, offering new insight into implant-induced electromagnetic heating and its implications for the safety and optimization of DEPF-based bone-healing therapies. Full article

While thinnings immediately reduce aboveground biomass, they promote growth by releasing the remaining trees from competition. The biomass removed in thinnings can be used for energy, thus enabling financial returns prior to final harvest and contributing to the global share of renewable energies. In this study, the effects of thinning on stand structure dynamics and potential residential bioheat utilisation scenarios are assessed for a broadleaved mixed even-aged stand. The results demonstrate that ten years after thinning, aboveground biomass increased, ensuring system sustainability and carbon stocks. Furthermore, an average potential yield of 1.1 Mg·ha⁻¹·a⁻¹ (dry basis) of low-ash forest by-products was obtained, offering a sustainable supply of solid biofuels. However, the energy conversion route chosen has major impacts on the solid bioenergy demand and sustainability. Based on theoretical scenarios, upgrading from traditional fireplaces to more efficient combustion systems may reduce the specific biomass consumption up to eight times for residential heat production. The results obtained in this study highlight the challenge and need to use thinning biomass sustainably in the face of growing bioenergy demands. Full article

This study addresses the management and optimization of decentralized bioresource energy generation under conditions of political instability, using Ukraine as a representative case. The research aims to enhance energy security and operational resilience where centralized energy infrastructure is vulnerable to disruption. A high-efficiency technology for decentralized heat generation is proposed, based on the direct combustion of non-standard agricultural biomass with a one-year renewal cycle. The methodology combines experimental and statistical analysis of biomass feeding processes with advanced three-dimensional modeling of mixture formation and combustion, as well as the development of an artificial intelligence-driven automated control system. The system enables the use of sunflower, rapeseed, wheat, corn, and other agricultural residues with variable particle size and moisture content of up to 40%, without the need for pre-drying or pelletization. An original jet–vortex bioheat generator and optimized dosing systems were designed to ensure continuous and stable combustion. An operational algorithm allowing stable performance within 25–100% of nominal capacity was formulated based on statistical evaluation of screw feeder behavior and optimization of adjustable electric drive parameters, ensuring thermal carrier temperature stability within ±1–2 °C. The main novelty lies in the integrated optimization framework combining unconventional biomass utilization, adaptive electric drive control, and AI-based automation to achieve high energy efficiency and environmental performance. The results indicate that such decentralized systems can substantially strengthen national energy security and support sustainable energy supply in unstable political environments. Full article

To achieve precise and safe laser acupuncture treatment, a computational model of the skin acupoint was constructed utilizing COMSOL Multiphysics (Version 6.1). This model incorporates its multilayer anatomical structure: the epidermis, papillary dermis, reticular dermis, hypodermis, and muscle layer. A coupled multiphysics approach integrating geometric optics, radiation beams, and bioheat transfer was employed to investigate the effects of light source parameters and cooling layers on the photothermal response and thermal damage of acupoints. Under optimized parameters (808 nm, 3 mm beam waist, 50 mW) with a 0.5 mm glycerol layer, 600 s irradiation achieved a stable dermal temperature (40.86–42.04 °C) and a negligible epidermal thermal damage factor (0.0063), significantly below the subclinical injury threshold of 0.15; under identical parameters, the dermal temperature for the Gaussian periodic pulsed source was maintained between 38.85 and 40.35 °C, with a corresponding epidermal thermal damage factor of merely 0.0010. The model exhibited good robustness, tolerating variations of ±5% in laser power and ±40% in glycerol layer thickness. The resultant temperature deviations in the epidermis and dermis were well within the safe range, and the thermal damage factor remained below the injury threshold. This work serves as a guideline for selecting laser acupuncture parameters according to acupoint depth. Full article

A computational approach for early breast cancer detection using Dynamic Infrared Thermography (DIT) was developed. Thermograms are represented by multivariate time series extracted from thermal hotspots in the breast, capturing five features: maximum and mean temperature, spatial heterogeneity, heat flux, and tumor depth, over 20 thermograms. Features are estimated based on the inverse solution of the Pennes bio-heat equation. Classification is performed using a Time Series Forest (TSF) and a Long Short-Term Memory (LSTM) network. The TSF achieved an accuracy of 86%, while the LSTM reached 94% accuracy. These results indicate that dynamic thermal responses under cold-stress conditions reflect tumor angiogenesis and metabolic activity, demonstrating the potential of combining multivariate thermographic sequences, biophysical modeling, and machine learning for non-invasive breast cancer screening. Full article

Background: Platelet-rich fibrin (PRF) is an autologous biomaterial utilized as an adjunct in dental implant surgeries owing to its significant biocompatibility, supra-physiological concentration of growth factors, and ability to speed either soft or hard tissue regeneration. Methods: Today, PRF is available in both solid and liquid forms with an average resorption period of roughly 2 weeks. While various research endeavors have attempted to utilize Solid-PRF as a barrier membrane in guided bone regeneration (GBR) and various other applications, its two-week resorption period has limited its use as a solo “barrier” membrane owing to its faster-than-ideal resorption properties. Results: Recent studies have demonstrated that by heating and denaturing Liquid-PRF/albumin, the resorption properties of the heated albumin gel could be extended from 2 weeks to 4–6 months by utilizing the Bio-Heat technology. This emerging technology was given the working name ‘extended-PRF’ or e-PRF, with many clinical indications being proposed for further study. Numerous clinicians have now utilized extended-PRF (e-PRF) membranes as a substitute for collagen barrier membranes in various clinical applications, such as guided tissue/bone regeneration, recession coverage, and lateral window sinus lifts. Conclusions: This two-part case series paper aims to first illustrate the evolution of techniques developed taking advantage of this new technology in clinical practice for alveolar ridge preservation. This includes four different methods of fabrication of e-PRF along with its application in clinical practice. This article discusses the clinical outcomes, including the advantages/disadvantages of utilizing each of the four separate techniques to prepare and utilize e-PRF membranes for ridge preservation. Full article

This work investigated the electrical, dielectric, and magnetic properties of ferrofluids containing Fe₃O₄ nanoparticles and their composites with chitosan (30–100 cP and 100–300 cP), relevant to magnetic hyperthermia. The nanoparticles were synthesized by coprecipitation and characterized using impedance spectroscopy, X-ray diffraction, scanning microscopy with X-ray microanalysis, Mössbauer spectroscopy, and calorimetry. The study showed that the chitosan coating altered the textural properties of Fe₃O₄, reducing the specific surface area from 76.3 m²/g to 68.9–72.5 m²/g. The zeta potential and particle size showed strong pH dependence. Impedance measurements showed that the conductivity of ferrofluids was frequency- and temperature-dependent, with both metallic and dielectric conductivity observed. The complex dielectric permittivity exhibited Maxwell–Wagner–Sillars interface polarization. Calorimetry revealed that specific absorption rate (SAR) ranged from 11.4 to 23.4 W/g, depending on the chitosan concentration and type, while the chitosan coating reduced SAR by 12–40%. These results confirm that the electrical and dielectric parameters of ferrofluids significantly influence their thermal capabilities, which is important for optimizing magnetic hyperthermia therapy when energy dissipation is considered in bio-heat models. Full article

This paper addresses the challenges of ice ball shape prediction and layout optimization in multi-probe cryoablation treatment through a comprehensive study integrating both simulation and experimental approaches. A three-dimensional numerical model of multi-probe cryoablation, coupled with phase change heat transfer, was developed using the Pennes bioheat equation. The model’s accuracy in predicting core physical phenomena, such as phase change processes and multi-probe thermal field superposition, was initially validated. The simulated and experimentally measured temperature profiles, along with the macroscopic ice ball shapes, were observed to be in excellent agreement (with an average error of 3.75% in the major and minor axes of the ice ball). Additionally, it was determined that a nine-probe layout with 1 cm probe spacing was optimal for generating a uniform low-temperature field. However, histological analysis of porcine liver tissue revealed inconsistencies between the model’s predicted damage boundaries and the actual observed diffuse biological damage transition zone, indicating the limitations of steady-state models relying solely on fixed critical damage threshold temperatures for accurately predicting the cell death region. This study not only provides a rigorously validated thermal-physical prediction tool for preoperative planning but also underscores the importance of incorporating time-temperature thermal dose effects into future models to bridge the gap from physical simulation to biological damage prediction, thus laying a crucial foundation for the development of precise cryoablation technologies. Full article

Energy production from burning biomass in bioheat plants involves the production of biomass fly ash (BFA). Due to its rich chemical composition, in the era of a circular economy, it should be reused, for example, for environmental purposes as a secondary raw material containing valuable macro- and micronutrients. Due to its alkaline nature, it can also be an alternative to commercial agricultural lime (CAL) for neutralizing the acidic reaction of agricultural soils. The basis for the presented research was a pot experiment with corn (Zea mays L.) as a test plant and increasing doses of BFA (16.20, 32.40, and 48.60 g pot⁻¹), which is equal to 6.99, 13.98, and 20.97 g of CAL pot⁻¹. The above doses were determined based on the neutralization value (NV) of BFA and CAL, calculated to neutralize the hydrolytic acidity of the soil (Hh) to 0.5, 1.0, and 1.5 Hh. The study analyzed the effect of BFA on the leaf greenness index (SPAD), plant height, yield, and chemical composition of corn, as well as macronutrient content. The observations indicate that BFA application positively modified the yield of both fresh mass and dry mass of corn and height of plants, and reduced the dry matter content compared to the effect obtained after CAL use. BFA caused a decrease in the total N and Ca content and a significant increase in P, K, and Na compared to the CAL-fertilized treatments. BFA significantly contributed to a narrowing of the Ca:P, Ca:Mg ratios, and a widening of the K:(Ca + Mg), and K:Ca ratios compared to the ionic balance observed in the CAL-fertilized corn. The obtained results allow us to conclude that fly ash from biomass combustion can be a valuable alternative to conventional soil deacidification agents used till now in agriculture. Full article

This paper presents an analysis of the phenomena that occur during photodynamic therapy (PDT). For this purpose, models of laser energy deposition, bioheat transfer, and reactions occurring during the PDT process were used. Light distribution was estimated on the base of optical diffusion equation, while for the bioheat analysis the Pennes formula has been used. The PDT reaction model includes equations related to the concentration of triplet oxygen, photosensitizer, and singlet oxygen. The tissue perfusion coefficient and the effective scattering coefficient have been assumed to be thermally damage dependent. Changes in blood velocity in capillary, which affects maximum oxygen supply in PDT model, were also considered. A way of modeling the abnormal vascular pattern in the tumor area was also proposed, and the initial distribution of triplet oxygen in the tumor region was determined on the Krogh cylinder model. At the stage of numerical calculation, the boundary element method, the finite difference method, and the shooting method were used. Full article