Towards an integrated neonatal brain and cardiac examination capability at 7 T: electromagnetic field simulations and early phantom experiments using an 8-channel dipole array

Objective Neonatal brain and cardiac imaging would benefit from the increased signal-to-noise ratio levels at 7 T compared to lower field. Optimal performance might be achieved using purpose designed RF coil arrays. In this study, we introduce an 8-channel dipole array and investigate, using simulations, its RF performances for neonatal applications at 7 T. Methods The 8-channel dipole array was designed and evaluated for neonatal brain/cardiac configurations in terms of SAR efficiency (ratio between transmit-field and maximum specific-absorption-rate level) using adjusted dielectric properties for neonate. A birdcage coil operating in circularly polarized mode was simulated for comparison. Validation of the simulation model was performed on phantom for the coil array. Results The 8-channel dipole array demonstrated up to 46% higher SAR efficiency levels compared to the birdcage coil in neonatal configurations, as the specific-absorption-rate levels were alleviated. An averaged normalized root-mean-square-error of 6.7% was found between measured and simulated transmit field maps on phantom. Conclusion The 8-channel dipole array design integrated for neonatal brain and cardiac MR was successfully demonstrated, in simulation with coverage of the baby and increased SAR efficiency levels compared to the birdcage. We conclude that the 8Tx-dipole array promises safe operating procedures for MR imaging of neonatal brain and heart at 7 T.

Measurement Analysis of Specific Absorption Rate in Human Body Exposed to a Base Station Antenna by Using Finite Difference Time Domain Techniques

The system analysis of specific absorption rate (SAR) in human body exposed to a base station antenna by using finite difference time domain techniques was presented in this research works. The objectives of this work are to evaluate the knowledge and awareness about SAR among human body and mobile base station. The paper investigates the electromagnetic wave absorption inside a human body. The human body has been identified using dataset based on 2D object considering different electrical parameters.The SAR convinced inside the human body model exposed to a radiating base station antenna (BSA) has been considered for multiple numbers of carrier frequencies and input power of 20 W/carrier at GSM 900 band.The distance (R) of human body from BSA is varied in the range of 0.1 m to 5.0 m. For the number of carrier frequency equal to one and R = 0.1 m,the concentrated value of whole-body average SAR obtained by FDTD technique is found to be 0.68 W/kg which decreases either with increase of R or decrease of number of carrier frequencies. Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to one.The performance accuracy of this analysis meets the high level condition by comparing with the relevant system development in recent time.

Integrated in Clothes Graphene Antenna with Low SAR for Wearable Body-Centric Communications

The design and fabrication of graphene based textile patch antennas, intended for use in the 2.45GHz ISM band, are presented. The antennas have simple geometries with rectangular, triangular, or circular shape and substrate materials made of four different fabrics suitable for wearable applications. Conductive graphene sheet is used for the active element patches of the twelve different proposed prototypes. The effects of the antenna geometry, the substrate selection and the graphene-textile fabrication process on the prototypes’ performance are studied. Several prototypes exhibit desirable characteristics, such as high gain, acceptable radiation pattern, low Specific Absorption Rate (SAR), relatively wide bandwidth, and coverage of the ISM band even under different bending conditions.

Synthesis of Betaine Copolymer for Surface Modification of Cotton Fabric by Enhancing Temperature-Sensitive and Anti-Protein Specific Absorption Performance

The growth and reproduction of microorganisms on fabrics could not only affect the wearability of textiles but also cause harm to human health, and it is an important problem that should be solved to reduce the adsorption and growth of microorganisms on the surface of the fabric. A series of ω-vinyl betaine copolymers were synthesized by catalytic chain transfer polymerization (CCTP) and were modified by mercapto-vinyl click chemistry to synthesize silane-modified betaine copolymers, which were used to treat the cotton fabric. The hydrophilic–hydrophobic transition performance and anti-protein specific adhesion performance of cotton fabric with the betaine copolymer were systematically investigated. The copolymer was confirmed to be successfully finished on the cotton fabric via 1H–NMR and FTIR. The cotton fabric, which was treated by the betaine copolymer, presented temperature response performance in the range of 30–55 °C and had excellent anti-protein adsorption performance. The treated fabric had the best temperature-sensitive and anti-protein specific absorption performance among all the specimens when the mass fraction of G06B in DMAPS was 6 wt.%.