Prototyping and Experimentation of a Closed-Loop Wireless Power Transmission with Channel Acquisition and Waveform Optimization

A systematic design of adaptive waveform for Wireless Power Transfer (WPT) has recently been proposed and shown through simulations to lead to significant performance benefits compared to traditional non-adaptive and heuristic waveforms. In this study, we design the first prototype of a closed-loop wireless power transfer system with adaptive waveform optimization based on Channel State Information acquisition. The prototype consists of three important blocks, namely the channel estimator, the waveform optimizer, and the energy harvester. Software Defined Radio (SDR) prototyping tools are used to implement a wireless power transmitter and a channel estimator, and a voltage doubler rectenna is designed to work as an energy harvester. A channel adaptive waveform with 8 sinewaves is shown through experiments to improve the average harvested DC power at the rectenna output by 9.8% to 36.8% over a non-adaptive design with the same number of sinewaves.Comment: accepted for publication in IEEE WPTC 201

Signal and System Design for Wireless Power Transfer : Prototype, Experiment and Validation

A new line of research on communications and signals design for Wireless Power Transfer (WPT) has recently emerged in the communication literature. Promising signal strategies to maximize the power transfer efficiency of WPT rely on (energy) beamforming, waveform, modulation and transmit diversity, and a combination thereof. To a great extent, the study of those strategies has so far been limited to theoretical performance analysis. In this paper, we study the real over-the-air performance of all the aforementioned signal strategies for WPT. To that end, we have designed, prototyped and experimented an innovative radiative WPT architecture based on Software-Defined Radio (SDR) that can operate in open-loop and closed-loop (with channel acquisition at the transmitter) modes. The prototype consists of three important blocks, namely the channel estimator, the signal generator, and the energy harvester. The experiments have been conducted in a variety of deployments, including frequency flat and frequency selective channels, under static and mobility conditions. Experiments highlight that a channeladaptive WPT architecture based on joint beamforming and waveform design offers significant performance improvements in harvested DC power over conventional single-antenna/multiantenna continuous wave systems. The experimental results fully validate the observations predicted from the theoretical signal designs and confirm the crucial and beneficial role played by the energy harvester nonlinearity.Comment: Accepted to IEEE Transactions on Wireless Communication

Waveform Optimization for Wireless Power Transfer with Nonlinear Energy Harvester Modeling

Far-field Wireless Power Transfer (WPT) and Simultaneous Wireless Information and Power Transfer (SWIPT) have attracted significant attention in the RF and communication communities. Despite the rapid progress, the problem of waveform design to enhance the output DC power of wireless energy harvester has received limited attention so far. In this paper, we bridge communication and RF design and derive novel multisine waveforms for multi-antenna wireless power transfer. The waveforms are adaptive to the channel state information and result from a posynomial maximization problem that originates from the non-linearity of the energy harvester. They are shown through realistic simulations to provide significant gains (in terms of harvested DC power) over state-of-the-art waveforms under a fixed transmit power constraint.Comment: paper to be presented at IEEE International Symposium on Wireless Communication Systems (ISWCS 2015

Micro-Engineered Devices for Motion Energy Harvesting

Published versio

Power processing circuits for electromagnetic, electrostatic and piezoelectric inertial energy scavengers

Accepted versio

CMOS Buck-Boost Power processing circuitry for powerMEMS generators

Accepted versio

Simulation toolkit for energy scavenging inertial micro power generators

Published versio

Single versus multiple human-equivalent doses of C. parvum in mice: neutralization of the anti-metastatic effect.

The murine dose of i.v. C. parvum (466 microgram) was compared with a single, low, human-equivalent dose of 70 microgram and with repeated weekly low doses. All treatments increased the antibody titre against C. parvum (CP). However, repeated doses stimulated a much higher titre than single doses. In all treated animals spleen weight peaked at 2 weeks and then fell. A single low dose caused a 3-fold increase, a single high dose or multiple low doses a 6-fold increase. Liver weight changes followed a similar pattern. Hepatosplenomegaly was prolonged by multiple doses. The effects of these treatments on Lewis tumour metastases were studied. A single high dose and a single low dose on the day of tumour implantation (Day 0) were equally effective at inhibiting pulmonary metastases. Repeated low doses starting on Day 0 were no more effective than a single dose. The effect of CP on survival after primary-tumour excision on Day 10 was observed. Low dose CP on Day 7 doubled the harmonic mean of survival time. Repeated doses were no more effective than a single dose. Low-dose prophylaxis up to 2 weeks before tumour significantly inhibited metastases. However, when repeated low-dose prophylaxis was combined with a single low dose on Day 0, the anti-metastatic effect was abrogated. This neutralization of the anti-metastatic effect of CP given on Day 0 was found to persist after a 13-week treatment-free interval. Possible mechanisms for this phenomenon are discussed