A high-performance transcutaneous battery charger for medical implants

Abstract

Abstract-As new functionality is added to the implantable devices, their power requirements also increase. Such power requirements make it hard for keeping such implants operational for long periods by non-rechargeable batteries. This result in a need for frequent surgeries to replace these batteries. Rechargeable batteries can satisfy the long-term power requirements of these new functions. To minimize the discomfort to the patients, the recharging of the batteries should be as infrequent as possible. Traditional battery charging methods have low battery charging efficiency. This means they may limit the amount of charge that can be delivered to the device, speeding up the depletion of the battery and forcing frequent recharging. In this paper, we evaluate the suitability of a state-of-theart general purpose charging method called current-pumped battery charger (CPBC) for implant applications. Using offthe-shelf components and with minimum optimization, we prototyped a proof-of-concept transcutaenous battery charger based on CPBC and show that the CPBC can charge a 100 mAh battery transcutaneously within 137 minutes with at most 2.1• C increase in tissue temperature even with a misalignment of 1.3 cm in between the coils, while keeping the battery charging efficiency at 85%.

A new single-stage AC-DC converter for medical implant devices

“…Efficiency of a power supply circuit is a critical factor for extending the battery life, thus reducing or eliminating the need for battery replacement surgeries. Wireless transcutaneous battery charging has been also actively researched as an alternative solution [5]- [7]. The power path in [5] exemplifies the powering system in medical implant devices.…”

“…However, the efficiency is limited due to the high voltage drop over the linear regulator [5]. Recent research further focuses on the battery charging strategy [6], [7]. The charger is also based on the linear regulator which means the efficiency is decided by the voltage drop between input and output.…”

High-efficiency high-current drive power converter IC for wearable medical devices

“…The efficiency of such type can be poor with higher conduction loss. In addition, high input AC voltage could cause high dropout voltage and result in lower efficiency on the LDO that is used to regulate output voltage [1,2]. Other than the diode bridge, Fig.…”