arXiv subjects

Alanson P. Sample

Publications and source records attributed to Alanson P. Sample.

3 recordsLinked to original sources

arXiv2026

Hierarchical resonators for localized charging in room-scale magnetoquasistatic wireless power systems

Magnetoquasistatic wireless power transfer can deliver substantial power to mobile devices over near-field links. Room-scale implementations, such as quasistatic cavity resonators, extend this capability over large enclosed volumes, but their efficiency drops sharply for centimeter-scale or misoriented receivers because the magnetic field is spatially broad and weakly coupled to small coils. Here, we introduce hierarchical resonators that act as selectively activated relays within a room-scale quasistatic cavity resonator, coupling to the ambient magnetic field and re-emitting a stronger local field near a target receiver. This architecture enables localized power delivery to miniature devices without requiring global reshaping of the room-scale cavity mode. Experimentally, the hierarchical link improves power transfer efficiency by more than two orders of magnitude relative to direct room-scale transfer and delivers up to 500 mW of DC power to a 15 mm receiver. We further demonstrate selective multi-relay operation and field reorientation for furniture-embedded charging scenarios. These results establish a scalable route to reconfigurable wireless power delivery for miniature and batteryless devices in room-scale environments.

physics.app-ph↗

arXiv2025

Room-scale magnetoquasistatic wireless power transfer using a cavity-based multimode resonator

Magnetoquasistatic wireless power transfer can be used to charge and power electronic devices such as smartphones and small home appliances. However, existing coil-based transmitters, which are composed of wire conductors, have a limited range. Here we show that multimode quasistatic cavity resonance can provide room-scale wireless power transfer. The approach uses multidirectional, widely distributed currents on conductive surfaces that are placed around the target volume. It generates multiple, mutually unique, three-dimensional magnetic field patterns, where each pattern is attributed to different eigenmodes of a single room-scale resonator. Using these modes together, a power delivery efficiency exceeding 37.1% can be achieved throughout a 3 m * 3 m * 2 m test room. With this approach, power exceeding 50 W could potentially be delivered to mobile receivers in accordance with safety guidelines.

physics.app-ph↗

arXiv2021

Wisecr: Secure Simultaneous Code Disseminationto Many Batteryless Computational RFID Devices

Emerging ultra-low-power tiny scale computing devices in Cyber-Physical Systems %and Internet of Things (IoT) run on harvested energy, are intermittently powered, have limited computational capability, and perform sensing and actuation functions under the control of a dedicated firmware operating without the supervisory control of an operating system. Wirelessly updating or patching the firmware of such devices is inevitable. We consider the challenging problem of simultaneous and secure firmware updates or patching for a typical class of such devices -- Computational Radio Frequency Identification (CRFID) devices. We propose Wisecr, the first secure and simultaneous wireless code dissemination mechanism to multiple devices that prevent malicious code injection attacks and intellectual property (IP) theft, whilst enabling remote attestation of code installation. Importantly, Wisecr is engineered to comply with existing ISO compliant communication protocol standards employed by CRFID devices and systems. We comprehensively evaluate Wisecr's overhead, demonstrate its implementation over standards-compliant protocols, analyze its security and implement an end-to-end realization with popular CRFID devices -- the open-source code is released on GitHub.

cs.CR↗