Wireless Power Transfer to Biomedical Implants Using a Class-E Inverter and a Class-DE Rectifier

In this article, we propose a strategy for the design of a wireless power transfer system consisting of a class-E inverter, a half-bridge class-DE rectifier, and two coupled coils. The system is optimized for maximum power transfer efficiency. The design is validated via a case study, for which a wireless power transfer link to a neuroprosthesis was designed. After circuit simulations, a prototype was realized and measured. There is a good agreement between the calculated, simulated and measured voltages and currents. The prototype delivers 80 mW, 7 V to a biomedical implant at 6.78 MHz, the transfer efficiency is 52 to 68%, depending on the alignment. The end-to-end efficiency, with the controller and gate driver also taken into account, is 39 to 57%. Electromagnetic and thermal simulations were performed to verify compliance with relevant safety regulations on specific absorption rate (SAR) levels, magnetic field strength, and heat generation in the implant, for separation distances between the coils of 8 to 15 mm, and transverse misalignment from 0 to 15 mm.</p

Interstitial Hyperthermia Device

According to one aspect, an interstitial hyperthermia device has an electrode structure to be coupled to an electric power source for providing an alternating electric field for heating up a patients tissue. The device is provided with a hollow source guide for conducting a radiation source capsule to be moved by a guidewire. The hollow source guide has an inner wall for guiding the source capsule and an outer wall to be contacted with the patients tissue. The outer wall is provided with the electrode structure arranged on a circumference of the outer wall of the hollow source guide and having a dielectric layer shielding the electrode structure from the patients tissue

An MR-compatible antenna and application in a murine superficial hyperthermia applicator

In this work, a novel magnetic resonance (MR)-compatible microwave antenna was designed and validated in a small animal superficial hyperthermia applicator. The antenna operates at 2.45 GHz and matching is made robust against production and setup inaccuracies. To validate our theoretical concept, a prototype of the applicator was manufactured and tested for its properties concerning input reflection, sensitivity for setup inaccuracies, environment temperature stability and MR-compatibility. The experiments show that the applicator indeed fulfils the requirements for MR-guided hyperthermia investigation in small animals: it creates a small heating focus (&lt;1 cm 3 ), has a stable and reliable performance (S 11 &lt; −15 dB) for all working conditions and is MR-compatible. </p

Low-Power Wireless Data Transfer System for Stimulation in an Intracortical Visual Prosthesis

There is a growing interest to improve the quality of life of blind people. An implanted intracortical prosthesis could be the last resort in many cases of visual impairment. Technology at this moment is at a stage that implementation is at sight. Making the data communication to and from the implanted electrodes wireless is beneficial to avoid infection and to ease mobility. Here, we focus on the stimulation side, or downlink, for which we propose a low-power non-coherent digital demodulator on the implanted receiver. The experimentally demonstrated downlink is on a scaled-down version at a 1 MHz carrier frequency showing a data rate of 125 kbps. This provides proof of principle for the system with a 12 MHz carrier frequency and a data rate of 4 Mbps, which consumes under 1 mW at the receiver side in integrated circuit (IC) simulation. Due to its digital architecture, the system is easily adjustable to an ISM frequency band with its power consumption scaling linearly with the carrier frequency. The tested system uses off-the-shelf coils, which gave sufficient bandwidth, while staying within safe SAR limits. The digital receiver achieved a reduction in power consumption by skipping clock cycles of redundant bits. The system shows a promising pathway to a low-power wireless-enabled visual prosthesis

Optimization of microwave coupled resonant-cavity filters

Based on a full-wave simulation model, we investigate how various optimization methods perform on a sensitive problem of a high-Q, nine-pole rectangular waveguide filter system with respect to its multi-mode scattering parameters

Analyzing developing brain-on-chip cultures with the calima calcium imaging tool

Brain-on-chip (BoC) models are tools for reproducing the native microenvironment of neurons, in order to study the (patho)physiology and drug-response of the brain. Recent developments in BoC techniques focus on steering neurons in their activity via microfabrication and via computer-steered feedback mechanisms. These cultures are often studied through calcium imaging (CI), a method for visualizing the cellular activity through infusing cells with a fluorescent dye. CAlciumImagingAnalyser 2.0 (CALIMA 2.0) is an updated version of a software tool that detects and analyzes fluorescent signals and correlates cellular activity to identify possible network formation in BoC cultures. Using three previous published data sets, it was demonstrated that CALIMA 2.0 can analyze large data sets of CI-data and interpret cell activity to help study the activity and maturity of BoC cultures. Last, an analysis of the processing speed shows that CALIMA 2.0 is sufficiently fast to process data sets with an acquisition rate up to 5 Hz in real-time on a medium-performance computer