Strain-invariant stretchable radio-frequency electronics.

Wireless modules that provide telecommunications and power-harvesting capabilities enabled by radio-frequency (RF) electronics are vital components of skin-interfaced stretchable electronics. However, recent studies on stretchable RF components have demonstrated that substantial changes in electrical properties, such as a shift in the antenna resonance frequency, occur even under relatively low elastic strains. Such changes lead directly to greatly reduced wireless signal strength or power-transfer efficiency in stretchable systems, particularly in physically dynamic environments such as the surface of the skin.

MATLAB-based innovative 3D finite element method simulator for optimized real-time hyperthermia analysis.

Background And Objective: Owing to the significant role of hyperthermia in enhancing the efficacy of chemotherapy or radiotherapy for treating malignant tissues, this study introduces a real-time hyperthermia simulator (RTHS) based on the three-dimensional finite element method (FEM) developed using the MATLAB App Designer.

Methods: The simulator consisted of operator-defined homogeneous and heterogeneous phantom models surrounded by an annular phased array (APA) of eight dipole antennas designed at 915 MHz. Electromagnetic and thermal analyses were conducted using the RTHS.

Conversion of the bronchial tree into a conforming electrode to ablate the lung nodule in a porcine model.

Background: Radiofrequency ablation (RFA) is one of the treatment options for lung nodules. However, the need for exact delivery of the rigid metal electrode into the center of the target mass often leads to complications or suboptimal results. To overcome these limitations, a concept of conforming electrodes using a flexible material has been tested in this study.

Wireless, Battery-Free, and Fully Implantable Micro-Coil System for 7 T Brain MRI.

An elegant solution for the concurrent transmission of data and power is essential for implantable wireless magnetic resonance imaging (MRI). This paper presents a self-tuned open interior microcoil (MC) antenna with three useful operating bands of 300 (7 T), 400, and 920 MHz, for blood vessel imaging, data telemetry, and efficient wireless transmission of power, respectively. The proposed open interior MC antenna contains two mirrorlike arms with diameters and lengths of 2.

Development of 60-GHz millimeter wave, electromagnetic bandgap ground planes for multiple-input multiple-output antenna applications.

For 60-GHz band communications, both the mutual coupling and transmission distance restrict the performance of a multiple-input multiple-output (MIMO) antenna array. Several studies presented different types of meta-materials and electromagnetic bandgap (EBG) structures to improve the performance of a MIMO antenna array at the 60-GHz band. In this paper, we presented the four-element MIMO patch antenna with different types of EBG structures for the millimeter wave (mmW)communications at the 60-GHz unlicensed industrial, scientific, and medical band.

Soft Materials, Stretchable Mechanics, and Optimized Designs for Body-Wearable Compliant Antennas.

Among the various methods to develop flexible wearable antennas, a serpentine, mesh structure has been a great interest because of its mechanical reliability upon applied strain. However, there is still a significant lack of design guidelines for the open-mesh concept that account for both material and electromagnetic (EM) properties of antennas. In this work, we introduce a comprehensive study of materials, mechanics, fabrication, and system integration for the development of stretchable dipole and patch antennas that have networks of two-dimensional serpentine patterns.

Fully Printed, Wireless, Stretchable Implantable Biosystem toward Batteryless, Real-Time Monitoring of Cerebral Aneurysm Hemodynamics.

This study introduces a high-throughput, large-scale manufacturing method that uses aerosol jet 3D printing for a fully printed stretchable, wireless electronics. A comprehensive study of nanoink preparation and parameter optimization enables a low-profile, multilayer printing of a high-performance, capacitance flow sensor. The core printing process involves direct, microstructured patterning of biocompatible silver nanoparticles and polyimide.

Adaptive Matching Transmitter With Dual-Band Antenna for Intraoral Tongue Drive System.

The intraoral Tongue Drive System (iTDS) is a wireless assistive technology that detects users' voluntary tongue gestures, and converts them to user-defined commands, enabling them to access computers and navigate powered wheelchairs. In this paper, we presented a transmitter (Tx) with adaptive matching and three bands (27, 433, and 915 MHz) to create a robust wireless link between iTDS and an external receiver (Rx) by addressing the effects of external RF interference and impedance variations of the Tx antenna in the dynamic mouth environment. The upper two Tx bands share a dual-band antenna, while the lower band drives a coil.

Stepped impedance resonators for high-field magnetic resonance imaging.

Multi-element volume radio-frequency (RF) coils are an integral aspect of the growing field of high-field magnetic resonance imaging. In these systems, a popular volume coil of choice has become the transverse electromagnetic (TEM) transceiver coil consisting of microstrip resonators. In this paper, to further advance this design approach, a new microstrip resonator strategy in which the transmission line is segmented into alternating impedance sections, referred to as stepped impedance resonators (SIRs), is investigated.

A method to localize RF B₁ field in high-field magnetic resonance imaging systems.

In high-field magnetic resonance imaging (MRI) systems, B₀ fields of 7 and 9.4 T, the RF field shows greater inhomogeneity compared to clinical MRI systems with B₀ fields of 1.5 and 3.

Pseudoinverse method for modal solutions of open dielectric waveguides.

The vector finite-element method in the interior and the boundary integral equation of the exterior domain are investigated in order to analyze open dielectric waveguides. Boundary conditions are obtained by applying the continuity of the magnetic and electric fields at the surface of the waveguide. Since both the finite-element method and boundary integral equations have the final matrices of the form Ax=lambdaBx, the pseudoinverse method with a penalty factor is used.

Analysis of open dielectric waveguides using the finite-element penalty method.

This paper analyzes open dielectric waveguides using the vector finite-element method and boundary integral equations derived from the second Green's theorem. This finite-element formulation, together with the boundary operator, is solved using a penalty function method. Comparison with previously published results shows good agreement for the analysis of the rectangular dielectric waveguide.