Near-field magnetic wireless systems have distinct advantages over their conventional far-field counterparts in water-rich environments, such as underwater, underground, and in biological tissues, due to lower power absorption. This paper presents a comprehensive review of near-field magnetic wireless power transfer (WPT) and communication technologies in a variety of applications from general free-space systems, to implantable biomedical devices we find of particular interest. To implement a fully wirelessly-powered implantable system, both high-efficiency power transfer and high-rate data communication are essential. This paper first presents the history and the fundamentals of near-field WPT and communication in free-space systems, followed by technical details for their specific use in implantable biomedical devices. Finally, this paper reviews recent advances in simultaneous wireless information and power transfer and highlights their applications in implantable biomedical systems. The knowledge reviewed in the paper could provide intuition in the design of various wireless and mobile systems such as wireless body area networks, small-cell 5G cellular, as well as in-body biomedical applications, especially for efficient power and data management and higher security.

Review of Near-Field Wireless Power and Communication for Biomedical Applications

With a wide scope to explore and harness the oceanic sources of interest, the field of underwater wireless sensor networks (UWSNs) is attracting a growing interest of researchers. Owing to the real-time remote data monitoring requirements, underwater acoustic sensor networks (UASNs) emerged as a preferred network to a great extent. In UASN, the limited availability and non-rechargeability of energy resources along with the relative inaccessibility of deployed sensor nodes for energy replenishments necessitated the evolution of several energy optimization techniques. Clustering is one such technique that increases system scalability and reduces energy consumption. Besides clustering, coverage and connectivity are two significant properties that decide the proper detection and communication of events of interest in UWSN due to unstable underwater environment. Underwater communication is also possible with non-acoustic communication techniques like radio frequency, magnetic induction, and underwater free-space optics. In this paper, we surveyed clustering, coverage, and connectivity issues of UASN and qualitatively compared their performance. Particularly, the impact of these non-conventional communication techniques on clustering, coverage, and connectivity aspects is demonstrated. Additionally, we highlighted some key open issues related to the UWSN. This paper provides a broad view of existing algorithms of clustering, coverage, and connectivity based on acoustic communication. It also provides a useful guidance to the researchers in UWSN from various other communication techniques’ perspective.

Review on Clustering, Coverage and Connectivity in Underwater Wireless Sensor Networks: A Communication Techniques Perspective

Enabling underwater wireless communications to conveniently interconnect various underwater deployed devices for data transmission, information sharing, and networking is among the most crucial issues in marine information networks. Apart from the conventional acoustic, optical, and electromagnetic techniques, the magnetic induction (MI) communication, as a promising alternative, has drawn significant attentions recently due to its inherent advantages in predictable channel responses, negligible propagation delay, and competitive energy consumption. In this paper, we attempt to provide a comprehensive and in-depth survey of the existing research on underwater MI communications, classified as the four topics of channel modeling, reliability guarantee, range extension, and capacity enhancement, and present the state-of-the-art advances on each topic. Specifically, the approaches for channel modeling of underwater MI communications, including proposed channel models and involved basic theories, are first summarized. Then, the existing works on reliability guarantee are expounded following the evolution of antenna design from traditional single-directional to advanced multi-directional MI antennas. Furthermore, as to range extension, two typical categories of MI relaying techniques, i.e., the MI waveguide and the active relaying techniques, are reviewed in detail. In particular, the potential of a hybrid relay transmission scheme proposed by us through flexible combination of these two techniques in achieving both energy-efficient and long-range underwater transmission is also addressed in this part. Finally, the existing approaches on extending or reusing the available frequency bands to enhance the underwater MI channel capacity are elaborated. Challenges and open issues that need to be further investigated related to each of the four topics are also profoundly discussed and analyzed in each part.

A Survey of Underwater Magnetic Induction Communications: Fundamental Issues, Recent Advances, and Challenges

Wearable technologies will play an important role in advancing precision medicine by enabling measurement of clinically-relevant parameters describing an individual's health state. The lifestyle and fitness markets have provided the driving force for the development of a broad range of wearable technologies that can be adapted for use in healthcare. Here we review existing technologies currently used for measurement of the four primary vital signs: temperature, heart rate, respiration rate, and blood pressure, along with physical activity, sweat, and emotion. We review the relevant physiology that defines the measurement needs and evaluate the different methods of signal transduction and measurement modalities for the use of wearables in healthcare.

Wearable Devices for Precision Medicine and Health State Monitoring

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Wireless Communication Systems From Rf Subsystems To 4g Enabling Technologies

The magnetic induction (MI)-based communications assume the applications, wherein standard electromagnetic (EM) wave and acoustic communications are not effective. The EM and acoustic-based communications do have high power loss, high propagation delays, very low data rates, and environment-dependent channel behavior. MI communications heavily depend upon the time varying magnetic field to convey information between transmitter and receiver. MI-based communications for non-conventional media (e.g., underwater or underground) exhibit several unique and promising qualities, such as constant channel behavior, negligible propagation delay, and large communications range. This paper surveys the current state-of-the-art magnetic induction-based communications for non-conventional media applications. The widely used communications techniques for non-conventional media are qualitatively compared. In particular, the advantages and the disadvantages of different communications techniques are analyzed in terms of different performance metrics. In addition, we highlight some important open issues related to the design of MI for non-conventional media. This survey aims to provide a useful guidance to the researchers in this area.

Magnetic Induction-Based Non-Conventional Media Communications: A Review

"Graphene is the smallest possible thinness layer of graphite, with a thickness of 0.34 nm" [1]. It is made up of sp 2 hybridized carbon atoms in such a way that each carbon atom bonded is attached to three others in a covalent bond, as shown in Figure 1(a) [2]. One s orbital and two p orbitals ( p x, p y) together result in sp 2 hybridization with 120d angles between the hybrid orbitals, forming a s-bond. Figure 1(b) shows the crystal structure of graphite, which consists of parallel carbon layers. The perpendicular p z orbital to the sp 2 hybrid orbital forms a p-bond. A weak Van der Waals force exists between the layers due to the p-bond. In the past, it was theoretically studied as the building block of graphitic materials with other dimensions [3], [4]. Because of the weak Van der Waals forces between the stacked layers of graphite in graphene, isolated graphene was considered to be thermodynamically unstable and, thus, was thought not to exist in reality [5]-[7].

The Promise of Graphene: A Survey of Microwave Devices Based on Graphene

We propose a chemical-vapor-deposited (CVD) diamond-based double-drift-region (DDR) impact avalanche transit-time diode (IMPATT) for use in microwave applications. CVD diamond is taken as the base substrate material. Simulations were carried out to perform direct-current (DC), small-signal, and noise analyses on the IMPATT. The results are in agreement with experimental reports. The IMPATT based on CVD diamond offers better performance compared with other materials reported to date at 26 GHz to 40 GHz. In the near future, this device could represent the best alternative for designers and semiconductor industry, due to its numerous advantages including higher DC-to-radiofrequency (RF) conversion efficiency (27.81%), highest power density (6.206 × 109 W m−2), minimum noise value (− 98.22 dBm), and best optimized conductance–susceptance profile with lower quality factor (0.0215).

Prospects of Impact Avalanche Transit-Time Diode Based on Chemical-Vapor-Deposited Diamond Substrate

A comparative study of small signal noise has been presented for n+-n-p-p+ double drift region (DDR) impact avalanche and transit time (IMPATT) diode. The comparison is made by taking different sem...

Ka band noise comparison for Si, Ge, GaAs, InP, WzGaN, 4H-SiC-based IMPATT diode

Through this paper, the effects of acoustic phonons on the noise performance of avalanche transit-time devices have been investigated and reported. For this study, a double-drift-region silicon-based impact avalanche transit-time diode has been considered at operating frequencies of 94 GHz, 140 GHz and 220 GHz. To analyze the acoustic phonon effects on noise performance, the interactions of charge carriers with acoustic deformation potential and piezoelectric acoustic phonons have been considered in addition to all possible types of scattering events. These effects have been analyzed through a numerical expression for the ionization rate of charge carriers and incorporated in the noise analysis. The noise performance is evaluated in terms of noise spectral density (NSD) and noise measure (NM). The results show that due to acoustic phonons, values of NSD and NM significantly increase.

Joydeep Sengupta

Papers

Magnetic Induction-Based Non-Conventional Media Communications: A Review

The Promise of Graphene: A Survey of Microwave Devices Based on Graphene

Prospects of Impact Avalanche Transit-Time Diode Based on Chemical-Vapor-Deposited Diamond Substrate

Ka band noise comparison for Si, Ge, GaAs, InP, WzGaN, 4H-SiC-based IMPATT diode

Noise performance of avalanche transit-time devices in the presence of acoustic phonons