An in-body implantable miniaturized slot dipole rectangular patch antenna operating in the Industrial, Scientific, and Medical (ISM) band (2.4-2.4835 GHz) for biomedical applications is presented in this paper. Primary reason behind choosing ISM band is its flexibility towards larger bandwidth with smaller size of antenna. The main specialty of this antenna is its tiny dimension & bendability which makes it practically implantable for in-body biomedical applications. Actual size of the antenna is (8.20×12.5×0.045) mm. For making it suitable for implementation, the antenna was immersed inside a human tissue model where proper electrical properties of the human tissue muscle model were maintained. All the parameter calculations and simulation results were suitable to support the Industrial, Scientific, and Medical (ISM) band in both bent and planar conditions. This antenna can be used for real time wireless monitoring of blood pressure, temperature, glucose level, and other in-body applications that functions in the ISM band. To make the designed antenna suitable for implantation, it is embedded in a silicon block which acts like a superstrate. Finally, the safety measurements were taken into account by stimulating the Specific Absorption Rate (SAR) distribution of the antenna to make it perfectly biocompatible.

A flexible implantable PIFA (Planar Inverted F Antenna) antenna for biomedical applications is proposed in this study. The main notability of this design refers to its subtle dimension, flexibility and subordinate thickness that makes it perfectly suitable for implementing inside human or animal tissues. The antenna is aimed to operate in the Industrial, Scientific and Medical (ISM) band (2.4-2.4835 GHz). The thickness of this antenna is only .735 mm, which implies that this antenna is reliable to perform under bent conditions. The antenna offers a compact design with a dimension of 9.48 mm × 7.8 mm × .735 mm (54.348 mm ³ ). Copper and Rogers R03010 are chosen as the patch material and substrate material accordingly. The antenna is encapsulated inside biocompatible material Rogers R03010 for safety concern in skin or muscle tissues. Several types of calculations and performance measurement of this antenna have been done by using CST Microwave studio in both planar and bent conditions by maintaining all the electrical properties of human skin tissue. Finally, Specific Absorption Rate (SAR) and thermal loss are evaluated to comply with the antenna safety issues.

In this paper, the performance comparison of an existing slot dipole flexible bendable antenna is carried out with a newly modified design, featuring balanced size miniaturization for implantable wireless communications. By introducing a minuscule dimension along with the use of low cost substrate and patch material, this proposed antenna has a heightened reliability and feasibility in turns of performing for biomedical applications. The proposed antenna is designed to operate in the Industrial, Scientific and Medical (ISM) band (2.4–2.4835 GHz). ISM band has been chosen because of its docility towards higher bandwidth with the decreasing size of antenna. The proposed antenna is designed for both planar and bendable scenarios. Silicon with thickness of 625μm is used as the biocompatible layer to encapsulate the antenna, giving a packed dimension of 65.57mm³ (12.55mm × 0.625mm × 8.36mm). The antenna is also immersed inside a human tissue model where all the electrical properties of the human tissue were maintained to study the sensitivity of the antenna's performance when subjected to in-body conditions. With the antenna inside the human tissue model, all its performance parameters are studied both in planer and bent cases. Finally, the Specific Absorption Rate (SAR) is evaluated to test whether the antenna is safe to be implanted inside a living body.

A dense unit cell array used in a metasurface for a high reflection angle (θ_r > 50°) leads to high coupling among the unit cells; thus, parasitic reflections are unavoidable. The up-do-date patch-based metasurfaces for high reflection angles were electrically large (> 80 λ²), but for a practical point of view, a more compact metasurface design is needed. As a solution for these issues, we use the folded dipole-based unit cells with closed-loop currents for low near-field coupling and design compact metasurfaces (~ 40 λ²) for high reflection angles (θ_r = 56° and 70°) at 10 GHz. The folded dipole unit cells are arranged according to the recently developed non-linear phase boundary condition for low harmonic reflections. As a counterpart, we also designed a metasurface using conventional patch-shaped unit cells with the same reflection phases (θ_r = 70°). In experiments, the folded dipole metasurface shows lower harmonic levels (θ_r = 0° and − 70°) and a comparable anomalous reflection (θ_r = 70°) versus the patch-shaped metasurface. The time-domain analysis demonstrates that the low harmonic levels from the folded dipole metasurface are due to low scattering from the guided waves and the edge scattering. The proposed compact folded dipole-based metasurface with low undesired harmonics can be used as a practical reflect-array for millimeter-wave communication links.

Low-temperature waste heat in the infrared (IR) wavelength region offers an opportunity to harvest power from waste energy and requires further investigation in order to find efficient conversion techniques. Although grating-coupled metal-oxide-semiconductor (MOS) diode devices offer efficient conversion from low and moderate-temperature thermal sources, the integration of such diodes with a nanoantenna structure has yet to be explored. We propose a bowtie nanoantenna coupled with a p-doped MOS diode for IR to direct current (DC) conversion without any bias voltage at 28.3 THz. The nanoantenna was designed and optimized to provide maximum field enhancement in a 4 nm-thick oxide layer at the resonant frequency. The device was fabricated following the complementary MOS (CMOS) fabrication process and measured in a custom DC and optical characterization setup using a 10.6 μm wavelength CO₂ laser. The results reveal two different types of devices with linear and nonlinear I-V curves having kΩ and MΩ zero-bias resistance, respectively. The linear device generates a micron-level open-circuit voltage (V_oc) with clear polarization dependence from the laser input, but the nonlinear case suffers from a weak noise-like signal. Finally, we analyze two types of devices using thermoelectric and tunneling effects and discuss the future direction of nanoantenna-integrated MOS devices for efficient IR harvesters.