Capacitive Coupler for Wireless Power Transfer to Intravascular Implant Devices

In this letter, we analyze a capacitive coupler for wireless power transfer (WPT) to intravascular implant devices using a stent that contacts the vessel wall for vasodilation as a power receiver. We focus on the effect of conductivity on the transfer efficiency of capacitive WPT and verify the relationship between the maximum transfer efficiency and conductivity based on an equivalent circuit, including arteries and body tissues. We also measure the permittivity and conductivity of biological tissues and explain the appropriate measurement method for each biological tissue. Then, we design the electrode size of the capacitive coupler, and the experimental results of CWPT are presented. We can transfer power into blood vessels through a subcutaneous fatty skin with an efficiency of 35% at 434 MHz, which is the ISM band.