Wireless Energy Harvesting Technologies

Wireless energy harvesting encompasses the capture and conversion of ambient electromagnetic, optical and mechanical energy into electrical power for electronic systems. Techniques range from near-field coupling, such as inductive and resonant magnetic transfer, to far-field methods that exploit radio-frequency (RF) and microwave beaming. Central to these approaches are rectennas—integrated antenna and rectifier units—that harvest RF energy from broadcast signals, dedicated power transmitters or solar-in-RF converters. Advances in materials science, metamaterials and microfabrication have enabled compact, flexible harvesters suitable for wearable, implantable and autonomous sensors in the Internet of Things (IoT). Simultaneous wireless information and power transfer (SWIPT) schemes further optimise spectrum use by combining data communication with energy delivery. Emerging applications include environmental monitoring, structural health sensing, biomedical implants, space-based solar power beaming and maintenance-free surveillance. Key challenges remain in maximising power conversion efficiency at low input power densities, ensuring alignment and safety in directed beams, and integrating energy storage or management circuits for uninterrupted operation. The global drive towards sustainable, battery-free devices has catalysed rapid multidisciplinary research, linking antenna design, semiconductor rectifiers, power electronics and regulatory frameworks to deliver resilient, universally deployable harvesters.

Research from Nature Portfolio

Recent studies have demonstrated a multi-service, highly sensitive rectifier that concurrently harvests urban RF energy at two frequency bands, optimising impedance matching and rectification over a broad input range (−40 to −10 dBm). The design employs a multi-resonant circuit to capture ambient transmissions in the 478–496 MHz and 852–869 MHz bands, achieving an effective conversion efficiency exceeding 50% under multi-tone excitation. Experimental results reveal a three- to seven-fold increase in DC output power compared with single-frequency rectification, signalling a significant step towards self-sustaining low-power electronics in dense metropolitan environments.

Research from all publishers

Flexible, wearable systems have been developed that integrate hybrid RF-solar energy-harvesting arrays with backscatter wireless communication for battery-free colour imaging. These conformable devices employ transparent antenna stacks for simultaneous power transfer and data backscatter, supporting continuous operation in varied lighting and RF environments while maintaining comfort and biocompatibility. A comprehensive review of antenna technologies highlights low-profile, multi-band, circularly polarised and array antennas tailored for ambient RF energy harvesting and wireless power transfer. Comparative analysis emphasises design trade-offs in bandwidth, efficiency and form factor, and identifies open issues in fabrication tolerances and real-world performance assessment. In the realm of directed power beaming, historical and recent microwave and millimetre-wave demonstrations underscore the maturity of scalable rectenna arrays and phased-array transmitters. Reports of in-orbit solar-to-RF modules and ground-based 100 kW transmitters affirm feasibility for space-based solar power, while regulatory and human-safety considerations are framed as critical enablers for future deployments.

Wireless Energy Harvesting Technologies publication trend

The graph below shows the total number of articles in wireless energy harvesting technologies across all publications each year (not limited to Nature Index journals).

Technical terms

Rectenna: An integrated antenna-rectifier combination that converts received RF energy into direct current.

Backscatter communication: A passive method that modulates and reflects ambient RF signals for data transmission without an active RF source.

Power conversion efficiency (PCE): The ratio of DC power output from an energy harvester to the incident RF or optical power.

Ambient RF energy: Electromagnetic energy present in the environment from broadcast transmitters, Wi-Fi, cellular networks and other sources.

Beamforming: The controlled steering of electromagnetic waves by phased-array antennas to focus power in a desired direction for efficient long-range transfer.

References

1. Multi-Service Highly Sensitive Rectifier for Enhanced RF Energy Scavenging. Scientific Reports (2015).
2. Flexible and wearable battery-free backscatter wireless communication system for colour imaging. npj Flexible Electronics (2024).
3. A Review on Antenna Technologies for Ambient RF Energy Harvesting and Wireless Power Transfer: Designs, Challenges and Applications. IEEE Access (2022).
4. Microwave and Millimeter Wave Power Beaming. IEEE Journal of Microwaves (2021).
5. History and Innovation of Wireless Power Transfer via Microwaves. IEEE Journal of Microwaves (2021).