Radio frequency (RF) energy transfer and harvesting techniques have recently become alternative methods to power the next-generation wireless networks As this emerging technology enables proactive energy replenishment of wireless devices, it is advantageous in supporting applications with quality-of-service requirements In this paper, we present a comprehensive literature review on the research progresses in wireless networks with RF energy harvesting capability, which is referred to as RF energy harvesting networks (RF-EHNs) First, we present an overview of the RF-EHNs including system architecture, RF energy harvesting techniques, and existing applications Then, we present the background in circuit design as well as the state-of-the-art circuitry implementations and review the communication protocols specially designed for RF-EHNs We also explore various key design issues in the development of RF-EHNs according to the network types, ie, single-hop networks, multiantenna networks, relay networks, and cognitive radio networks Finally, we envision some open research directions

Wireless Networks With RF Energy Harvesting: A Contemporary Survey

Interest in Wireless Body Area Networks (WBANs) has increased significantly in recent years thanks to the advances in microelectronics and wireless communications. Owing to the very stringent application requirements in terms of reliability, energy efficiency, and low device complexity, the design of these networks requires the definition of new protocols with respect to those used in general purpose wireless sensor networks. This motivates the effort in research activities and in standardisation process of the last years. This survey paper aims at reporting an overview of WBAN main applications, technologies and standards, issues in WBANs design, and evolutions. Some case studies are reported, based on both real implementation and experimentation on the field, and on simulations. These results have the aim of providing useful insights for WBAN designers and of highlighting the main issues affecting the performance of these kind of networks.

A Survey on Wireless Body Area Networks: Technologies and Design Challenges

This survey summarizes almost 50 years of research and development in the field of Augmented Reality AR. From early research in the1960's until widespread availability by the 2010's there has been steady progress towards the goal of being able to seamlessly combine real and virtual worlds. We provide an overview of the common definitions of AR, and show how AR fits into taxonomies of other related technologies. A history of important milestones in Augmented Reality is followed by sections on the key enabling technologies of tracking, display and input devices. We also review design guidelines and provide some examples of successful AR applications. Finally, we conclude with a summary of directions for future work and a review of some of the areas that are currently being researched.

/pdf/a-survey-of-augmented-reality-2ce6xet7y5.pdf

A Survey of Augmented Reality

In this paper, we review recent advances in the development of flexible thermoelectric materials and devices for wearable human body-heat energy harvesting applications. We identify various emerging applications such as specialized medical sensors where wearable thermoelectric generators can have advantages over other energy sources. To meet the performance requirements for these applications, we provide detailed design guidelines regarding the properties of the material, device dimensions, and gap fillers by performing realistic device simulations with important parasitic losses taken into account. For this, we review recently emerging flexible thermoelectric materials suited for wearable applications, such as polymer-based materials and screen-printed paste-type inorganic materials. A few examples among these materials are selected for thermoelectric device simulations in order to find optimal design parameters for wearable applications. Finally we discuss the feasibility of scalable and cost-effective manufacturing of thermoelectric energy harvesting devices with desired dimensions.

Flexible thermoelectric materials and device optimization for wearable energy harvesting

Recent advances in wearable electronics combined with wireless communications are essential to the realization of medical applications through health monitoring technologies. For example, a smart contact lens, which is capable of monitoring the physiological information of the eye and tear fluid, could provide real-time, noninvasive medical diagnostics. However, previous reports concerning the smart contact lens have indicated that opaque and brittle components have been used to enable the operation of the electronic device, and this could block the user's vision and potentially damage the eye. In addition, the use of expensive and bulky equipment to measure signals from the contact lens sensors could interfere with the user's external activities. Thus, we report an unconventional approach for the fabrication of a soft, smart contact lens in which glucose sensors, wireless power transfer circuits, and display pixels to visualize sensing signals in real time are fully integrated using transparent and stretchable nanostructures. The integration of this display into the smart lens eliminates the need for additional, bulky measurement equipment. This soft, smart contact lens can be transparent, providing a clear view by matching the refractive indices of its locally patterned areas. The resulting soft, smart contact lens provides real-time, wireless operation, and there are in vivo tests to monitor the glucose concentration in tears (suitable for determining the fasting glucose level in the tears of diabetic patients) and, simultaneously, to provide sensing results through the contact lens display.

Soft, smart contact lenses with integrations of wireless circuits, glucose sensors, and displays

This paper presents an ultra-low power batteryless energy harvesting body sensor node (BSN) SoC fabricated in a commercial 130 nm CMOS technology capable of acquiring, processing, and transmitting electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG) data. This SoC utilizes recent advances in energy harvesting, dynamic power management, low voltage boost circuits, bio-signal front-ends, subthreshold processing, and RF transmitter circuit topologies. The SoC is designed so the integration and interaction of circuit blocks accomplish an integrated, flexible, and reconfigurable wireless BSN SoC capable of autonomous power management and operation from harvested power, thus prolonging the node lifetime indefinitely. The chip performs ECG heart rate extraction and atrial fibrillation detection while only consuming 19 μW, running solely on harvested energy. This chip is the first wireless BSN powered solely from a thermoelectric harvester and/or RF power and has lower power, lower minimum supply voltage (30 mV), and more complete system integration than previously reported wireless BSN SoCs.

A Batteryless 19 $\mu$ W MICS/ISM-Band Energy Harvesting Body Sensor Node SoC for ExG Applications

We present progress toward a wirelessly-powered active contact lens comprised of a transparent polymer substrate, loop antenna, power harvesting IC, and micro-LED. The fully integrated radio power harvesting and power management system was fabricated in a 0.13 μm CMOS process with a total die area of 0.2 mm2. It utilizes a small on-chip capacitor for energy storage to light up a micro-LED pixel. We have demonstrated wireless power transfer at 10 cm distance using the custom IC and on-lens antenna.

A Fully Integrated RF-Powered Contact Lens With a Single Element Display

Recent advances in ultra-low power chip design techniques, many originally targeting wireless sensor networks, will enable a new generation of body-worn devices for health monitoring. We utilize the state-of-the-art in low power RF transmitters, low voltage boost circuits, subthreshold processing, biosignal front-ends, dynamic power management, and energy harvesting to realize an integrated reconfigurable wireless body-area-sensor node (BASN) SoC capable of autonomous power management for battery-free operation.

A batteryless 19μW MICS/ISM-band energy harvesting body area sensor node SoC

Advances in electronic-neural interfaces have shown great potential for both neuroscience research and medical devices. Much of the work to date has focused on short-range inductive links for power and communication transfer [1]. There is an emerging need for active miniaturized systems that stream neural data in the far field, which would enable the observation of brain activity in unconstrained animals such as mice or moths. Such systems cannot rely on near-field power transfer, and must be powered by small batteries or energy harvesters. We present a 500µW fully integrated neural interface that wirelessly streams a digitized neural waveform over 15m.

A 500µW neural tag with 2µV rms AFE and frequency-multiplying MICS/ISM FSK transmitter

For true low-power peer-to-peer wireless links for sensing, link symmetry must be maintained unlike in [1,2] where the burden is shifted to the receiver In addition, the transceiver power dissipation and performance should be adaptive to save power when the link distance is short We present a 120μW MICS/ISM band receiver with −90dBm sensitivity at a data-rate of 200kb/s with BER<01% The receiver incorporates a 44μW low-power (LP) mode that achieves −70dBm sensitivity at 200kb/s and 01% BER At a lower data-rate of 20kb/s, the LP mode can be used as a wake-up receiver with increased sensitivity of −75dBm with 1% BER and 38μW power consumption

J. Pandey

Papers

A Batteryless 19 $\mu$ W MICS/ISM-Band Energy Harvesting Body Sensor Node SoC for ExG Applications

A Fully Integrated RF-Powered Contact Lens With a Single Element Display

A batteryless 19μW MICS/ISM-band energy harvesting body area sensor node SoC

A 500µW neural tag with 2µV rms AFE and frequency-multiplying MICS/ISM FSK transmitter

A 120μW MICS/ISM-band FSK receiver with a 44μW low-power mode based on injection-locking and 9x frequency multiplication