Wireless Power Transfer Approaches for Medical Implants: A Review

Abstract

Wireless power transmission (WPT) is a critical technology that provides an alternative for wireless power and communication with implantable medical devices (IMDs). This article provides a study concentrating on popular WPT techniques for IMDs including inductive coupling, microwave, ultrasound, and hybrid wireless power transmission (HWPT) systems. Moreover, an overview of the major works is analyzed with a comparison of the symmetric and asymmetric design elements, operating frequency, distance, efficiency, and harvested power. In general, with respect to the operating frequency, it is concluded that the ultrasound-based and inductive-based WPTs have a low operating frequency of less than 50 MHz, whereas the microwave-based WPT works at a higher frequency. Moreover, it can be seen that most of the implanted receiver’s dimension is less than 30 mm for all the WPT-based methods. Furthermore, the HWPT system has a larger receiver size compared to the other methods used. In terms of efficiency, the maximum power transfer efficiency is conducted via inductive-based WPT at 95%, compared to the achievable frequencies of 78%, 50%, and 17% for microwave-based, ultrasound-based, and hybrid WPT, respectively. In general, the inductive coupling tactic is mostly employed for transmission of energy to neuro-stimulators, and the ultrasonic method is used for deep-seated implants.

Pain-Administrable Neuron Electrode with Wireless Energy Transmission: Architecture Design and Prototyping

“…However, the angle of the octahedral wire loop would be very close to the inner wall of the receiver case manufactured in titanium, leading to significant energy loss on the receiver side. Therefore, we modified the wire loop design to a round shape in the second wire loop design, in which the radius of the receiver and transmitter wire loop was 12 mm and 15 mm [20], respectively (Figure 3). The overall transmission efficiency reached 30%, providing 120 mW power transfer which is sufficient for most SoC power requirements [18,21].…”

MEMS inductor fabrication and emerging applications in power electronics and neurotechnologies

“…MEMS inductors and magnetic devices also find important applications in the field of biomedical devices and systems, including microfluidics (nanobead trapping 109,110 , magnetic sensing 111,112 and biotarget sorting 113 ), nuclear magnetic resonance (NMR) spectroscopy 114,115 , implantable biomedical devices [116][117][118] , magnetic stimulation, and excitation (excitable cells 119 and neurostimulation 116 ). There are review papers covering the first three application categories, such as microfluidics 120 , magnetic sensing 111,121 , NMR 122 , wireless power transfer for implantable medical devices 123 , and NMR technologies for biomedical applications 124 . However, there is no review on the last application category.…”

Mechanical Energy Sensing and Harvesting in Micromachined Polymer-Based Piezoelectric Transducers for Fully Implanted Hearing Systems: A Review

“…Generally, an implanted medical device is used for sensing or stimulating by which it serves as a diagnostic tool or is used for treatment practices. A patient who is suffering from neural system disorder uses implantable stimulators [ 25 ], Parkinson’s symptoms can be eased via deep brain stimulators [ 26 ] and a hearing impaired person uses a cochlear implant for hearing restoration [ 27 ]. These medical implants, including cardiac pacemakers, retinal implants and infusion pumps, are considered small-sized and low-powered electronic devices.…”