Wearable and implantable medical devices (IMDs) have come a long way in the past few decades and have contributed to the development of many personalized health monitoring and therapeutic applications. Sustaining these devices with reliable and long-term power supply is still an ongoing challenge. This review discusses the challenges and milestones in energizing wearable and IMDs using the RF energy harvesting (RFEH) technique. The review highlights the main integrating frontend blocks such as the wearable and implantable antenna design, matching network, and rectifier topologies. The advantages and bottlenecks of adopting RFEH technology in wearable and IMDs are reviewed, along with the system elements and characteristics that enable these devices to operate in an optimized manner. The applications of RFEH in wearable and IMDs medical devices are elaborated in the final section of this review. This article summarizes the recent developments in RFEH, highlights the gaps, and explores future research opportunities.

In this article, we present a low-cost 2×2 metasurface-based rectenna array operating at the 2.45 GHz industrial, scientific, and medical (ISM) band for powering wearable medical sensors (WMS). The proposed antenna is a novel textile-based metasurface interlayer patch (meta-patch) antenna fabricated on a felt fabric substrate, replacing the conventional ground plane with a grounded metasurface consisting of a 3×3 unit cell array. A single excitation port is used for both the patch antenna and the metasurface to improve gain, efficiency, and bandwidth. The meta-patch antenna achieved a high gain of 7 dB, an efficiency of 77%, and an enhanced bandwidth of 120 MHz. The rectifier adopts a seven-stage Cockcroft-Walton voltage multiplier (CWVM) topology fabricated on a rigid substrate. To evaluate the performance of the meta-patch rectenna array and the effect of adding more elements, we tested the proposed meta-patch rectenna in single-element, 2×1 array, and 2×2 array configurations under continuous RF power. The single-element, 2×1 rectenna array, and 2×2 rectenna array achieved power conversion efficiencies (PCE) of 52%, 53%, and 56%, with DC output powers of 414 μW, 429 μW, and 450 μW, respectively, at an input power of -1 dBm. The results demonstrate the potential of the proposed rectenna arrays for efficiently energizing low-power WMS.

With the dramatic evolution in networks nowadays, an equivalent growth of challenges has been depicted toward implementing and deployment of such networks. One of the serious challenges is the security where wide range of attacks would threat these networks. Denial-of-Service (DoS) is one of the common attacks that targets several types of networks in which a huge amount of information is being flooded into a specific server for the purpose of turning of such server. Many research studies have examined the simulation of networks in order to observe the behavior of DoS. However, the variety of its types hinders the process of configuring the DoS attacks. In particular, the Distributed DoS (DDoS) is considered to be the most challenging threat to various networks. Hence, this paper aims to accommodate a comprehensive simulation in order to figure out and detect DDoS attacks. Using the well-known simulator technique of NS-2, the experiments showed that different types of DDoS have been characterized, examined and detected. This implies the efficacy of the comprehensive simulation proposed by this study.

This paper presents the design, fabrication, and performance evaluation of a flexible loop antenna integrated with LC (inductor-capacitor) sensors for wireless dielectric sensing in oral care applications. The antenna, implemented on a flexible substrate, enables conformal placement and reliable inductive coupling with passive LC sensors, facilitating non-invasive detection of dielectric property changes in biofluids. The flexible antenna was also tested at various bending angles. Difference in S11 magnitude for the bending angle of 0° and 40° was 2.5 dB with the magnitude being −17.5 dB for 0° and −15 dB for 40°. Two sensor types—big and small spiral laminated LC structures (BSL and SSL) were characterized under various test media, including deionized water, artificial saliva, and multiple concentrations of rosemary essential oil emulsions. Experimental results demonstrate stable resonance behavior under mechanical deformation and effective frequency shifts corresponding to liquid permittivity changes. Performance comparisons with conventional PCB and wire loop antennas confirm that the flexible design achieves comparable sensitivity with the frequency shift for all the antennas being around 100 MHz for BSL and 200 MHz for SSL in the liquids tested. The system exhibits strong linearity (R² > 0.98) in distinguishing environmental permittivity, highlighting its potential for future integration into wireless biosensing platforms for real-time, oral health diagnostics.