ABSTRACT
From 2007 in US and from 2022 in EU it is mandatory to use TPMS monitoring in new cars. Sensors mounted in tires require a continuous power supply, which currently only is from batteries. Piezoelectric energy harvesting is a promising technology to harvest energy from tire movement and deformation to prolong usage of batteries and even avoid them inside tires. This study presents a simpler method to simultaneous model the tire deformation and piezoelectric harvester performance by using a new simulation approach - dynamic bending zone. For this, angular and initial velocities were used for rolling motion, while angled polarization was introduced in the model for the piezoelectric material to generate correct voltage from tire deformation. We combined this numerical simulation in COMSOL Multiphysics with real-life measurements of electrical output of a piezoelectric energy harvester that was mounted onto a tire. This modelling approach allowed for 10 times decrease in simulation time as well as simpler investigation of systems parameters influencing the output power. By using experimental data, the simulation could be fine-tuned for material properties and for easier extrapolation of tire deformation with output harvested energy from simulations done at low velocity to the high velocity experimental data.
ABSTRACT
Biocompatibility restrictions have limited the use of magnetic nanoparticles for magnetic hyperthermia therapy to iron oxides, namely magnetite (Fe3O4) and maghemite (γ-Fe2O3). However, there is yet another magnetic iron oxide phase that has not been considered so far, in spite of its unique magnetic properties: ε-Fe2O3. Indeed, whereas Fe3O4 and γ-Fe2O3 have a relatively low magnetic coercivity, ε-Fe2O3 exhibits a giant coercivity. In this report, the heating power of ε-Fe2O3 nanoparticles in comparison with γ-Fe2O3 nanoparticles of similar size (â¼20 nm) was measured in a wide range of field frequencies and amplitudes, in uncoated and polymer-coated samples. It was found that ε-Fe2O3 nanoparticles primarily heat in the low-frequency regime (20-100 kHz) in media whose viscosity is similar to that of cell cytoplasm. In contrast, γ-Fe2O3 nanoparticles heat more effectively in the high frequency range (400-900 kHz). Cell culture experiments exhibited no toxicity in a wide range of nanoparticle concentrations and a high internalization rate. In conclusion, the performance of ε-Fe2O3 nanoparticles is slightly inferior to that of γ-Fe2O3 nanoparticles in human magnetic hyperthermia applications. However, these ε-Fe2O3 nanoparticles open the way for switchable magnetic heating owing to their distinct response to frequency.
ABSTRACT
We developed a novel biodetection method for influenza virus based on AC magnetic susceptibility measurement techniques (the DynoMag induction technique) together with functionalized multi-core magnetic nanoparticles. The sample consisting of an incubated mixture of magnetic nanoparticles and rolling circle amplified DNA coils is injected into a tube by a peristaltic pump. The sample is moved as a plug to the two well-balanced detection coils and the dynamic magnetic moment in each position is read over a range of excitation frequencies. The time for making a complete frequency sweep over the relaxation peak is about 5 minutes (10 Hzâ»10 kHz with 20 data points). The obtained standard deviation of the magnetic signal at the relaxation frequency (around 100 Hz) is equal to about 10-5 (volume susceptibility SI units), which is in the same range obtained with the DynoMag system. The limit of detection with this method is found to be in the range of 1 pM.
ABSTRACT
We have used magnetic particles to study specific binding of prostate specific antigen (PSA) to the surfaces of the bioparticles. The used particles have a mean diameter of about 130 nm and are placed in phosphate buffer saline (PBS). Each particle is composed of clusters of magnetic single domains of magnetite, which are covered with dextran. Changes in surface chemistry of the particles give rise to a change in the hydrodynamic volume of the particles. The later is mirrored by the changed frequency response of the complex magnetic susceptibility of a fluid containing these particles. Using ordinary induction coils and the lock-in amplifier technique it is possible to measure the complex magnetic susceptibility of the particle solution in a frequency range from about 10 Hz up to 10 kHz. From the measurement of the complex susceptibility versus the excitation frequency (both at the excitation frequency as well as at higher harmonics) we have shown that it is possible to quantitatively study the binding of PSA to the surfaces of the magnetic particles and thus to determine the PSA concentration in solution containing known concentration of nanoparticles functionalised with a monoclonal PSA antibody. Our method allows to perform an immunoassay in a single step and is much faster and cheaper compared to conventional ELISA procedures.
