Multi-Resonator Wireless Inductive Power Link for Wearables on the 2D Surface and Implants in 3D Space of the Human Body.

This paper presents a novel resonance-based, adaptable, and flexible inductive wireless power transmission (WPT) link for powering implantable and wearable devices throughout the human body. The proposed design provides a comprehensive solution for wirelessly delivering power, sub-micro to hundreds of milliwatts, to deep-tissue implantable devices (3D space of human body) and surface-level wearable devices (2D surface of human skin) safely and seamlessly. The link comprises a belt-fitted transmitter (Belt-Tx) coil equipped with a power amplifier (PA) and a data demodulator unit, two resonator clusters (to cover upper-body and lower-body), and a receiver (Rx) unit that consists of Rx load and resonator coils, rectifier, microcontroller, and data modulator units for implementing a closed-loop power control (CLPC) mechanism. All coils are tuned at 13.56 MHz, Federal Communications Commission (FCC)-approved industrial, scientific, and medical (ISM) band. Novel customizable configurations of resonators in the clusters, parallel for implantable devices and cross-parallel for wearable devices and vertically oriented implants, ensure uniform power delivered to the load, PDL, enabling natural Tx power localization toward the Rx unit. The proposed design is modeled, simulated, and optimized using ANSYS HFSS software. The Specific Absorption Rate (SAR) is calculated under 1.5 W/kg, indicating the design's safety for the human body. The proposed link is implemented, and its performance is characterized. For both the parallel cluster (implant) and cross-parallel cluster (wearable) scenarios, the measured results indicate: 1) an upper-body PDL exceeding 350 mW with a Power Transfer Efficiency (PTE) reaching 25%, and 2) a lower-body PDL surpassing 360 mW with a PTE of up to 20%, while covering up to 92% of the human body.

Toward a Smart Sensing System to Monitor Small Animal's Physical State via Multi-Frequency Resonator Array.

This article presents a highly scalable and rack-mountable wireless sensing system for long-term monitoring (i.e., sense and estimate) of small animal/s' physical state (SAPS), such as changes in location and posture within standard cages. The conventional tracking systems may lack one or more features such as scalability, cost efficiency, rack-mount ability, and light condition insensitivity to work 24/7 on a large scale. The proposed sensing mechanism relies on relative changes of multiple resonance frequencies due to the animal's presence over the sensor unit. The sensor unit can track SAPS changes based on changes in electrical properties in the sensors near fields, appearing in the resonance frequencies, i.e., an Electromagnetic (EM) Signature, within the 200 MHz-300 MHz frequency range. The sensing unit is located underneath a standard mouse cage and consists of thin layers of a reading coil and six resonators tuned at six distinct frequencies. ANSYS HFSS software is used to model and optimize the proposed sensor unit and calculate the Specific Absorption Rate (SAR) obtained under 0.05 W/kg. Multiple prototypes have been implemented to test, validate, and characterize the performance of the design by conducting in vitro and in vivo experiments on Mice. The in-vitro test results have shown a 15 mm spatial resolution in detecting the mouse's location over the sensor array having maximum frequency shifts of 832 kHz and posture detection with under 30° resolution. The in-vivo experiment on mouse displacement resulted in frequency shifts of up to 790 kHz, indicating the SAPS's capability to detect the Mice's physical state.

Wireless Power Transmission with Uniform Power Delivery in the 3D Space of the Human Body using Resonators in Parallel.

This paper presents a novel resonance-based multi-coil wireless power transmission (WPT) system for powering implantable devices inside the 3D space of the human body. This design consists of a power amplifier, a transmitter coil, a cluster of resonators in parallel configuration, and a receiver unit, working at 13.56 MHz (the FCC-approved ISM-band). The proposed cluster configuration of the resonators in parallel configuration guarantees homogenous electromagnetic fields and uniform wireless power distribution in the 3D space of the body. It localizes the transmitted power at the receiver location naturally by activating the resonators near the receiver. We have modeled the proposed inductive link and the human body with HFSS software to optimize the design and study the body's safety by evaluating the Specific Absorption Rate (SAR) level. The proposed WPT system is implemented, and the measured results show that the inductive link with multiple resonators in parallel configuration can continuously deliver power, >120 mW, wirelessly inside the 3D space of the human-torso with a power transfer efficiency (PTE) of 15%, uniformly. We have also extended the coverage area to the human forearm by paralleling resonators with the resonators in the central body. The power delivered to the load and PTE between the resonators on the forearm area are measured >90 mW and ~14%, respectively.