The present study reports the synthesis and physico-chemical characterization of Mn1−xZnxFe2O4 (x = 0.5, 0.4, 0.3, 0.2, 0.1) nanoparticles-based magnetic fluids with reference to magnetic fluid ...hyperthermia. The properties of these fluids are studied using XRD, FTIR, TGA, VSM and the induction heating equipment operated at 330 kHz. The heating response of the fluids is investigated within the safety limit of H·f (4.8 *108 A/m-s). The study is also extended to simulate it for the agarose gel phantom system. The power absorption by these samples in distilled water and in agarose gel is calculated to compare with the experimentally observed value. To the best of the author's knowledge, no study of temperature sensitive magnetic fluid is reported on agarose gel, which simulates or phantom an in vivo condition. Results analysis show that the control of hyperthermia temperature is possible at lower fields and frequencies for the A91 sample with the smallest possible concentration, which can be acceptable for in vitro study.
•A vibration energy harvester based on the levitation of magnets in magnetic fluid is proposed.•A liquid spring with variable stiffness coefficient is designed.•Helical coils and planar coils are ...used together to improve output voltage.•The vibration energy harvester has excellent performance under weak vibration.
Using vibration energy harvester (VEH) to achieve self-power supply is an effectively way to ensure long-term use of electronic devices. In this paper, an electromagnetic VEH using magnetic fluid (MF) as lubricant and liquid spring is proposed, the VEH uses a hollow shell with variable internal diameter together with MF to form a liquid spring with variable stiffness coefficient to replace the traditional mechanical or magnetic spring, and planar coils and helical coils are used together to harvest the vibration energy, thereby broadening response frequency, improving energy harvest efficiency, and reducing VEH volume and damping. The influence of MF on the lubrication, liquid spring, and vibration state is studied theoretically, and the induced voltage is simulated. A crank-slider linkage has been built to test the performance of VEH, and the influence of vibration frequency, mass of MF, and coil type on the output performance has been studied during a 7.5 mm reciprocating linear motion of VEH. Results show that an appropriate amount MF can improve the output voltage by 173 % at 3.25 Hz, but too much MF will cause a rapid drop in output voltage. Helical coils generate higher voltage than planar coils, and the output power density of the helical coil is 0.92 mW/cm3 at 8.5 Hz. The energy management module can manage electric energy well, and half wave rectifier with low forward voltage drop may be more suitable for VEH with low output voltage. Besides, the VEH delivers a 1.36 mW/cm3 power density with a 10 Ω load when it is swung by human at 6.4 Hz.
Magnetic fluid seal(MFS) is one of the most mature applications of magnetic fluid(MF) and is widely used in numerous fields. When applying the MFS at − 55 ℃(the low temperature), it will lead to a ...high initial torque situation and a noticeable seal capacity reduction. This situation results in sealing failure and impedes the normal device startup. In this study, we synthesized MF based on polyalpha-olefins-3.5 (PAO-3.5), demonstrating fluidity at − 55 ℃, a saturated magnetization of 46.7 kA/m, and stability exceeding 2 months. The low pour point of PAO-3.5 based MF positions them as a good material choice for MFS applications in low temperature. And a structure of field-controlled MFS to control the magnetic field in sealing gap was proposed. To emphasis the necessity of the control of magnetic field, empirical equations were employed to model the viscosity and yield stress of MF under varying magnetic field strengths and temperatures, explaining the impacts of these factors. And the starting torque of MFS in specific conditions can be predicted. Notably, the use of field-controlled MFS have decreases in starting torque during non-pressure-resistant scenario, pressure-resistant scenario and long-term use.
A novel magnetic field sensing system based on surface plasma resonance (SPR) optical fiber sensor and filled with magnetic fluid (MF) is proposed and demonstrated for the first time. In the magnetic ...field SPR optical fiber sensor, SPR is excited by Ag as metallic material and MF is filled into the capillary sealed with epoxy glue, which utilizes the tunable refractive index (RI) of MF, and the transmission spectrum will change with different magnetic field intensities. The magnetic-optic effect of MF and the high RI sensitivity of optical fiber SPR sensor are utilized to enhance the sensitivity of the novel magnetic field sensor significantly. In the experiment, the performances of the magnetic field sensing system are tested by applying different measured magnetic fields. The final results indicated that a sensitivity of 303 pm/Gs is achieved. Compared with other optical fiber magnetic field sensors, the advantages of the proposed sensor in this paper are simple structure, small in size, easy to make, low cost, high sensitivity, and anti-interference.
The present study reports the synthesis and physico-chemical characterization of Mn1−xZnxFe2O4 (x = 0.5, 0.4, 0.3, 0.2, 0.1) nanoparticles-based magnetic fluids with reference to magnetic fluid ...hyperthermia. The properties of these fluids are studied using XRD, FTIR, TGA, VSM and the induction heating equipment operated at 330 kHz. The heating response of the fluids is investigated within the safety limit of H·f (4.8 *108 A/m-s). The study is also extended to simulate it for the agarose gel phantom system. The power absorption by these samples in distilled water and in agarose gel is calculated to compare with the experimentally observed value. To the best of the author’s knowledge, no study of temperature sensitive magnetic fluid is reported on agarose gel, which simulates or phantom an in vivo condition. Results analysis show that the control of hyperthermia temperature is possible at lower fields and frequencies for the A91 sample with the smallest possible concentration, which can be acceptable for in vitro study.
•The synthesis and physico-chemical characterization of Mn1−xZnxFe2O4 nanoparticles (x = 0.5, to 0.1) based magnetic fluids is reported.•The heating response of the fluids is investigated within the safety limit of H·f (4.8 *108 A/m-s).•The power absorption by these samples are calculated to compare with the experimentally observed value.•To the best of author’s knowledge, study of temperature sensitive magnetic fluid in agarose gel is not reported yet.•Results show that the A91 sample controls hyperthermia temperature at lower field, frequency and lowest concentration.
A highly sensitive reflective Fabry-Perot (FP) magnetic field sensor using magnetic fluid (MF) based on the Vernier effect is presented and experimentally verified. Capillary action acts as an ...injection of MF into an FP cavity, which is composed of a single-mode fiber (SMF), capillary glass tube, and a short section of SMF coated with gold film. Vernier effect is formed by the MF cavity and air cavity in the FP magnetic field sensor, where the surface of MF is concave. The refractive index (RI) of MF depends on the magnetic field, and therefore, the wavelength of the reflection spectrum of the fabricated sensor can be sensitive to the magnetic field. The magnetic field sensor's sensitivity is up to 1.02602 nm/Gs from 118.768 to 166.261 Gs, and the resolution is 0.0078 Gs. The sensor shows good linearity within the range of 71.317-231.751 Gs, and the linearity is larger than 0.999. In this article, a new type FP cavity fabricated by splicing SMF inside the capillary glass tube is proposed, and MF can be injected into the FP cavity, which can also be applied to other liquids to generate Vernier effect. The concave surface of MF is creatively applied to the sensors, and the experimental verification is carried out in a capillary glass tube, which provides a basis on the capillary action of other fluids in fiber sensing.
A magnetic field sensor is proposed based on the combination of magnetic fluid (MF) and an optical microfiber mode interferometer (MMI). It is measured that the MMI is highly sensitive to ambient ...refractive index (RI) with a high sensitivity up to 16,539nm/RIU while RI of the MF is changeable with an external magnetic field strength. By monitoring wavelength shift of transmission spectrum of the MMI, magnetic field measurement is realized with a maximum sensitivity of −293pm/Oe in the range of 0–220Oe.
A kind of magnetic field sensor is proposed, which is based on symmetrically side-polished photonic crystal fiber (PCF) with regular hexagonal air holes. Magnetic fluid is used as the magnetic field ...sensitive material. The polished surfaces are coated with Indium Tin Oxide (ITO) film to generate Lossy Mode Resonance (LMR) for magnetic field sensing. The obtained magnetic field sensitivity is 466.81 pm/Oe, which can be further adjusted by changing the thickness of the ITO film. The comprehensive sensing performance is evaluated by defining the figure-of-merit (FOM). The proposed structure is simple and has the capability of mass production, which has great development space in the future.
Replacing conventional cancer treatment methods like chemotherapy, which has many adverse effects, with new methods such as magnetic fluid hyperthermia, is one of the significant challenges. In this ...study, the effect of adding different MnO2 wt% to 20SiO2‐50FeO‐15CaO‐15Na2O glass-ceramic was studied. Maghemite, hematite, jacobsite and sodium calcium silicate phases were crystallized in the glass ceramics. Absorption bands of maghemite with a completely regular crystal structure were observed in the range of 472 and 560 cm−1 wavenumbers. The investigation of the magnetic properties also showed that the saturation magnetization of the samples increased from 21.5 emu/g to 30.80 emu/g by increasing the MnO2 from 0 to 15 wt%. The highest amount of heat loss under alternating magnetic field was also measured for the same sample and its value was 18 °C. Hydroxyapatite with cauliflower morphology was also observed in the phase and structural investigations of the samples immersed in the simulated body fluid.
•With the increase of the MnO2 percentage, the maximum magnetization of the samples increased from 21.5 emu/g to 30.80 emu/g.•Hydroxyapatite with cauliflower morphology was crystallized on the surface of the samples immersed in the simulated body fluid.•During the heat treatment, in addition to maghemite, ferromagnetic jacobsite phase also crystallized in the samples.•With the increase of MnO2, the amount of hysteresis loss under the alternating magnetic field increased and the temperature increase under the alternating magnetic field was measured to be 18°C.
•The influence of temperature on magetorheology was studied.•Thermal interaction is proved to be one of the main influencing factors in magnetorheology.•A novel structural parameter was proposed .
...The influence of temperature on the inertial structures in magnetic fluid was previously assumed to be based on a single mechanism. In this work, specialized rheological experiments were performed and their results have shown that different structural evolution paths can take place under the function of hydrodynamic and thermal interaction. The widely adopted Mason number was proved to be unsuitable to describe the magnetoviscous effect of magnetic fluids under different temperatures. To give a proper description on the combined effect of magnetic dipolar interaction, hydrodynamic interaction and thermal interaction in magnetic colloidal system, a novel structural number S was proposed and found to be applicable to superimposed the data under various temperatures onto a master curves.
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