This article describes the manufacturing technology of biocompatible flexible strain-sensitive sensor based on Ecoflex silicone and multi-walled carbon nanotubes (MWCNT). The sensor demonstrates resistive behavior. Structural, electrical, and mechanical characteristics are compared. It is shown that laser radiation significantly reduces the resistance of the material. Through laser radiation, electrically conductive networks of MWCNT are formed in a silicone matrix. The developed sensor demonstrates highly sensitive characteristics: gauge factor at 100% elongation −4.9, gauge factor at 90° bending −0.9%/deg, stretchability up to 725%, tensile strength 0.7 MPa, modulus of elasticity at 100% 46 kPa, and the temperature coefficient of resistance in the range of 30–40 °С is −2 × 10−3. There is a linear sensor response (with 1 ms response time) with a low hysteresis of ≤3%. An electronic unit for reading and processing sensor signals based on the ATXMEGA8E5-AU microcontroller has been developed. The unit was set to operate the sensor in the range of electrical resistance 5–150 kOhm. The Bluetooth module made it possible to transfer the received data to a personal computer. Currently, in the field of wearable technologies and health monitoring, a vital need is the development of flexible sensors attached to the human body to track various indicators. By integrating the sensor with the joints of the human hand, effective movement sensing has been demonstrated.
Degenerative disease of the intervertebral discs (DDD) is currently a serious problem facing the world community. The surgical methods and conservative therapy used today, unfortunately, do not stop the pathological process, but serve as a palliative method that temporarily relieves pain and improves the patient’s quality of life. Therefore, at present, there is an active search for new methods of treating DDD. Among new techniques of treatment, biological methods, and minimally invasive surgery, including the use of laser radiation, which, depending on the laser parameters, can cause ablative or modifying effects on the disc tissue, have acquired considerable interest. Here, we analyze a new approach to solving the DDD problem: laser tissue modification. This review of publications is focused on the studies of the physicochemical foundations and clinical applications of a new method of laser reconstruction of intervertebral discs. Thermomechanical action of laser radiation modifies tissue and leads to its regeneration as well as to a long-term restoration of disc functions, elimination of pain and the return of patients to normal life.
We study the effect of high hydrostatic pressure on 3D polymerized fullerite C60. We do not observe further structural changes until 150 GPa after a formation of 3D C60 under hydrostatic pressure 28 GPa. It is experimentally shown that the obtained samples consist of different clusters formed by sp3 bonds with a different set of force constants, the values of which vary within 20% and exceed the diamond force constants by the factor of 1.3–1.5. The influence of the exposure of laser radiation on the process of 3D polymerization of C60 under pressure was found. Increasing of the exposure by the factor of 15 leads to a decrease in the bulk modulus of 3D C60 from 610 GPa to 504 GPa.
The prethreshold processes on the surface of copper and its alloys are investigated. In the absence of obvious traces of melting, while preserving the metal in a condensed state, under a nanosecond ultraviolet laser radiation energy density of 0.1–1.0 J/cm2, manifestations of high-temperature plastic deformation were observed. These are sliding and cracking along grain boundaries, within which crystallographic slipping was observed. A microprotrusion was formed on the surface of the irradiated zone, which was outwardly similar the distribution of laser radiation in the spot. The height of the microprotrusion reached 1 µm, and sometimes even more. An increase in the number of impacting impulses led to the accumulation of damage. The data obtained are in many ways similar to the acoustoplastic, electroplastic, and magnetoplastic effects. By analogy, we consider it possible to call the discovered effect optoplastic.
The influence of an electric field on the plasma of an optical discharge in subsonic and supersonic air flows has been studied experimentally. The presence of a weak electric field practically does not affect the size of the plasma formation, but, regardless of the configuration of the field lines and the polarity of the applied voltage, it leads to a decrease in the probability of optical breakdown. The experiment has shown that the plasma created by focused laser radiation is very sensitive to the presence of an electric field. When a voltage exceeding 22 kV was applied to the ring electrodes, powerful quasi-stationary streamers were formed in the flow. The presence of an optical discharge plasma made it possible to create an electric discharge in fields with an intensity below the breakdown threshold of the medium. The effect of quenching and the processes of development of an optical discharge were studied depending on the speed and characteristics of the electric field. Quenching of the optical discharge was observed when a voltage of 22 kV and higher was applied. Despite the preservation of the geometric dimensions of the optical discharge, the high-temperature region in the flow can be increased by using electric streamers. This leads to an increase in the energy supplied to the flow, and thus allows combustion to be initiated and flame stabilized at higher flow rates.
Key words: experimental modeling, laser radiation, optical breakdown, electric field, electric discharge, sub- and supersonic air flow.