Mechanic Stress Generated by a Time-Varying Electromagnetic Field on Bone Surface

Bone cells sense mechanical load, which is essential for bone growth and remodeling. In a fracture, this mechanism is compromised. Electromagnetic stimulation has been widely used to assist in bone healing, but the underlying mechanisms are largely unknown. A recent hypothesis suggests that electromagnetic stimulation could influence tissue biomechanics; however, a detailed quantitative understanding of EM-induced biomechanical changes in the bone is unavailable. This paper used a muscle/bone model to study the biomechanics of the bone under EM exposure. Due to the dielectric properties of the muscle/bone interface, a time-varying magnetic field can generate both compressing and shear stresses on the bone surface, where many mechanical sensing cells are available for cellular mechanotransduction. I calculated these stresses and found that the shear stress is significantly greater than the compressing stress. Detailed parametric analysis suggests that both the compressing and shear stresses are dependent on the geometrical and electrical properties of the muscle and the bone. These stresses are also functions of the orientation of the coil and the frequency of the magnetic field. It is speculated that the EM field could apply biomechanical influence to fractured bone, through the fine-tuning of the controllable field parameters

Synthesis and characterization of magnetic nanoparticles for bioactive bone implant materials

A poly(methyl methacrylate) based composite coating containing magnetic nanostructures is developed that has the potential to equip passive titanium-based bone implants with the functionality of exercising an electromagnetic stimulus on bone regeneration. The thermal synthesis of maghemite nanoflowers is investigated, using iron chlorides in the presence of sodium hydroxide in a solvent mixture of N-methyldiethanolamine and diethylene glycol. A coating routine is developed to obtain a thin polymer film containing evenly dispersed magnetic nanoflowers.Eine Polymethylmethacrylat-basierte und magnetische Nanostrukturen enthaltende Kompositbeschichtung wird entwickelt, die das Potential hat, Titan-basierte Knochenimplantate mit der Funktionalität auszustatten, Knochenregeneration elektromagnetisch zu stimulieren. Die thermische Synthese magnetischer Nanoflowers mittels Eisen(II)- und Eisen(III)chlorid in der Gegenwart von Natriumhydroxid und einer Mischung der Lösungsmittel N-Methyldiethanolamin und Diethylenglycol wird untersucht. Eine Beschichtungsroutine wird entwickelt, die Nanoflowers gleichmäßig in einen dünnen Polymerfilm einbettet

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 297)

This bibliography lists 89 reports, articles and other documents introduced into the NASA scientific and technical information system in April, 1987

Electromagnetic pollution alert: Microwave radiation and absorption in human organs and tissues

Electromagnetic radiation from communication and electronic devices, networks, systems and base stations has drawn concern due to excessive global usage with increasing power and operating frequency level. Numerous previous researches only focus on how the radiation from certain frequency ranges of particular devices could harm specific human organs and tissues, resulting in distinct symptoms. In this research, electromagnetic propagation and properties in fourteen human organs and tissues were analyzed and investigated based on the organs and tissues’ electromagnetic and mechanical parameters, and chemical composition. Counting the organs and tissues as electromagnetic materials, their permittivity and conductivity, computed by a 4-Cole-Cole mode, directly respective to the operating frequency, are interrelated to wave behavior and hence influence the organs’ response. Tests were conducted in 1GHz to 105GHz system settings, covering most microwave frequency uses: 2.4GHz of 4G-LTE, WiFi, Bluetooth, ZigBee, and the 5G ranges: 28GHz of 5G-mmW and 95GHz of 5G-IoT. Trial human organs and tissues were placed in the wave propagation direction of 2.4GHz and 28GHz dipole antennas, and a waveguide port operating from 95-105GHz. The quantitative data on the effects of 5G penetration and dissipation within human tissues are presented. The absorbance in all organs and tissues is significantly higher as frequency increases. As the wave enters the organ-tissue model, the wavelength is shortened due to the high organ-tissue permittivity. Skin-Bone-Brain layer simulation results demonstrate that both electric and magnetic fields vanish before passing the brain layer at all three focal frequencies of 2.4GHz, 28GHz, and 100GHz

Aerospace Medicine and Biology. A continuing bibliography with indexes

This bibliography lists 244 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1981. Aerospace medicine and aerobiology topics are included. Listings for physiological factors, astronaut performance, control theory, artificial intelligence, and cybernetics are included

Acoustic Therapy as Mechanical Stimulation of Osteogenesis

Acoustic therapy is a branch of mechanotherapy. This modality of treatment can be used for osteogenesis-related orthopaedic disorders. Because bone cells are responsive to acoustic forces, specially designed devices were developed to generate acoustic forces in the form of low-intensity pulsed ultrasound, extracorporeal shock waves or radial pressure waves. With the developed devices, it became possible to provide patients an alternative, or adjunctive, treatment for pathologies involving bone homeostasis, that is, the balance of bone formation and bone resorption. The so-called acoustic therapy (low-intensity pulsed ultrasound stimulation, LIPUS; extracorporeal shock wave therapy, ESWT; and radial pressure wave therapy, RPWT) acts through physical phenomena produced when acoustic waves are transmitted into living tissue and converted to biological reactions, thereby activating signalling pathways that drive a cellular response in favour of osteogenesis. In this chapter, an extensive review of the literature was performed to provide the reader the “state of the art” about the physical phenomena, molecular events and clinical uses of acoustic forces for osteogenesis-related orthopaedics disorders

Design, Construction and Validation of a New Generation of Bioreactors for Tissue Engineering Applications.

132 p.The thesis reports on the design, fabrication and validation of a new generation of bioreactors for cell culture stimulation, in order to improve cell proliferation in advanced tissue engineering strategies. Bioreactors are developed to take advantage of responsive materials allowing to mimic cell microenvironments, resembling some of the most common physical stimuli within the human body. Some stimuli can be produced by polymer-based scaffolds such as magnetoelectric, which can work as mechanical and electrical actuators.Two types of bioreactors were developed: one for bone tissue engineering through magnetoelectric stimulation (through mechanical vibration and piezoelectricity) and another for muscle tissue engineering through mechanical stretching and controlled current impulses.This project encompasses several fields of engineering such as device engineering, design, mechanics and electronics, having also into account proper material selection and the final biomedical application

Effect of Surface Treatment on the Conductivity of Polyurethane-Carbon Composites

The effect of plasma surface treatment on the mechanical and electrical properties was investigated by comparing untreated particulate carbon filler and treated carbon filler in a polyurethane matrix. For achieving this goal, samples of the composites were prepared with different percentages of carbon fillers (0 – 50 wt %) and conductivity measurements, dynamic mechanical analysis, mechanical properties, infrared spectroscopy and scanning electron microscopy were used to determine the effect of surface modification and concentration. The conductivity measurements showed that the percolation threshold was shifted to lower concentrations of carbon as compared to the predicted value especially for the untreated carbon filled samples. The untreated filled carbon composite samples exhibited this behavior due to precipitation of filler particles during the solvent casting of the film. In terms of mechanical properties (dynamic and transient), the effect of filler content and filler surface treatment was noted. FT-IR results indicates some degree of interaction between the treated filler surface and polyurethane. Scanning electron microscopy showed that composites based on a modified filler had better dispersion