Search Results (3)

This study aimed to develop a novel Transdermal Energy Transmission System (TETS) device that addresses the driveline complications faced by patients with advanced heart failure (HF). Our TETS device utilizes a two-channel configuration with a very-low duty cycle and a pulsed RF power transmission technique, along with elliptically shaped flexible coil inductive coupling elements. We integrated a battery charging controller module into the TETS, enabling it to recharge an implanted Lithium-Ion (Li-Ion) battery that powers low-power-rated Circulatory Assist Devices, or left ventricular assist devices (LVADs). Benchtop measurements demonstrated that the TETS delivered energy from the implanted coils to the battery charging module, at a charging rate of up to 2900 J/h, presented an average temperature increase (ΔT) of 3 °C. We conducted in vivo measurements using four porcine models followed by histopathological analysis of the skin tissue in the implanted coils areas. The thermal profile analysis from the in vivo measurements and the calculated charging rates from the current and voltage waveforms, in porcine models, indicated that the charging rate and temperature varied for each model. The maximum energy charging rate observed was 2200 J/h, with an average ΔT of 3 °C. The exposed skin tissue histopathological analysis results showed no evidence of tissue thermal damage in the in vivo measurements. These results demonstrate the feasibility of our developed TETS device for wireless driving implanted low-power-rated LVADs and Li-Ion charging. Full article

This article presents a coil couple-based transcutaneous energy transmission system (TETS) for wirelessly powering implanted artificial hearts. In the TETS, the performance of the system is commonly affected by the change in the position of the coupling coils, which are placed inside and outside the skin. However, to some extent, the influence of coupling efficiency caused by misalignment can be reduced by optimizing the coil. Thus, different types of coils are designed in this paper for comparison. It has been found that the curved coil better fits the surface of the skin and provides better performance for the TETS. Various types of curved coils have been designed in response to observed bending deformations, dislocations, and other coupling variations in the curved coil couple. The numerical model of the TETS is established to analyze the effects of the different types of coils. Subsequently, a series of experiments are designed to evaluate the resilience to misalignment and to verify the heating of the coil under conditions of severe coupling misalignment. The results indicated that, in the case of misalignment of the coils used in artificial hearts, the curved transmission coil demonstrated superior efficiency and lower temperature rise compared to the planar coil. Full article

This article presents the development of a power loss emulation (PLE) system device to study and find ways of mitigating skin tissue heating effects in transcutaneous energy transmission systems (TETS) for existing and next generation left ventricular assist devices (LVADs). Skin thermal profile measurements were made using the PLE system prototype and also separately with a TETS in a porcine model. Subsequent data analysis and separate computer modelling studies permit understanding of the contribution of tissue blood perfusion towards cooling of the subcutaneous tissue around the electromagnetic coupling area. A 2-channel PLE system prototype and a 2-channel TETS prototype were implemented for this study. The heating effects resulting from power transmission inefficiency were investigated under varying conditions of power delivery levels for an implanted device. In the part of the study using the PLE setup, the implanted heating element was placed subcutaneously 6–8 mm below the body surface of in vivo porcine model skin. Two operating modes of transmission coupling power losses were emulated: (a) conventional continuous transmission, and (b) using our proposed pulsed transmission waveform protocols. Experimental skin tissue thermal profiles were studied for various levels of LVAD power. The heating coefficient was estimated from the porcine model measurements (an in vivo living model and a euthanised cadaver model without blood circulation at the end of the experiment). An in silico model to support data interpretation provided reliable experimental and numerical methods for effective wireless transdermal LVAD energization advanced solutions. In the separate second part of the study conducted with a separate set of pigs, a two-channel inductively coupled RF driving system implemented wireless power transfer (WPT) to a resistive LVAD model (50 Ω) to explore continuous versus pulsed RF transmission modes. The RF-transmission pulse duration ranged from 30 ms to 480 ms, and the idle time (no-transmission) from 5 s to 120 s. The results revealed that blood perfusion plays an important cooling role in reducing thermal tissue damage from TETS applications. In addition, the results analysis of the in vivo, cadaver (R1Sp2) model, and in silico studies confirmed that the tissue heating effect was significantly lower in the living model versus the cadaver model due to the presence of blood perfusion cooling effects. Full article