Blood perfusion cooling effects in transcutaneous energy transfer systems for driving next generation heart pumps

This work focuses on developing Transcutaneous Energy Transfer Systems (TETS) to power wirelessly the next generation of artificial heart pumps, particularly Left-Ventricular Assist Devices (LVADs). Conventional TETS use inductive coupling for transferring relatively high-power across the skin but are associated with significant skin heating effects. Thus, TETS design requires to minimise skin-tissue thermal damage. We have developed a multi-channels TETS capable of transferring up to 16W utilizing pulsed transmission waveform protocols for mitigating skin heating effects. A dual-channel inductively coupled RF power transmission prototype (inhouse built), for wireless power delivery to a resistive LVAD model (50Ω), capable of providing both continuous and the pulsed RF-transmission modes. Adjustable RF-transmission pulse duration ranges from 30ms to 480ms, and idle time (no-transmission) from 5s to 120s. Experimental results of estimated skin tissue thermal profile heating coefficient for the in-vivo (alive) pig model, both pulsed and continuous transmission modes were 7.74x10-4±(2.59x10-4) ºC/s and 1.28x10-3±(3.73x10-4) ºC/s respectively, and in the cadaver pig model (placebo), for pulsed and continuous modes: 1.59x10-3±(6.11x10-4) ºC/s & 1.46x10-3±(3.3x10-4) ºC/s respectively. In conclusion, the blood thermal perfusion plays a vital cooling role to reduce skin-tissue damage in TETS. The results analysis of in-vivo (alive-model) and placebo (cadaver-model) studies confirmed that tissue heating effect was significantly lower in the living-model (versus cadaver-model) due to presence of blood perfusion cooling effects.