Extending the Limits of Wireless Power Transfer to Miniaturized Implantable Electronic Devices

Abstract

Implantable electronic devices have been evolving at an astonishing pace, due to the development of fabrication techniques and consequent miniaturization, and a higher efficiency of sensors, actuators, processors and packaging. Implantable devices, with sensing, communication, actuation, and wireless power are of high demand, as they pave the way for new applications and therapies. Long-term and reliable powering of such devices has been a challenge since they were first introduced. This paper presents a review of representative state of the art implantable electronic devices, with wireless power capabilities, ranging from inductive coupling to ultrasounds. The different power transmission mechanisms are compared, to show that, without new methodologies, the power that can be safely transmitted to an implant is reaching its limit. Consequently, a new approach, capable of multiplying the available power inside a brain phantom for the same specific absorption rate (SAR) value, is proposed. In this paper, a setup was implemented to quadruple the power available in the implant, without breaking the SAR limits. A brain phantom was used for concept verification, with both simulation and measurement data.

Endovascular deep brain stimulation: Investigating the relationship between vascular structures and deep brain stimulation targets

“…5). Indeed, despite significant advances in recent years, high-energy power transfer across greater distances (centimeters) remains a major challenge [51]. Emerging technologies such as inductive and capacitive coupling schemes, and ultrasonics, however, constitute promising avenues that may enable efficient long range power transfer in the future [52].…”

Development of a battery-free ultrasonically powered functional electrical stimulator for movement restoration after paralyzing spinal cord injury

“…Wireless powering of implantable devices utilizes an energy transduction method to generate electrical energy from vibrational, electromagnetic, electrostatic, infrared radiant and/or ultrasound energy, through specific conversion [23]. Recent developments of implantable medical devices suggest that it might be more feasible to utilize wireless power transfer for electrical stimulation therapy compared to the classical power supply methods, such as battery implants [20]. The method of using harvested energy from external sources to stimulate nerve or muscle would be more endurable and could help to avoid multiple surgeries for replacing the battery or wire as the power can be wirelessly delivered to the implant [47].…”

A Fully Implantable Wireless Bidirectional Neuromodulation System for Mice

“…The flexible PCB construction allows for minimum thickness, but with the drawback that deformation of the flex coil during assembly causes a shift in inductance and thereby the resonant frequency, although careful assembly can mitigate this problem. Supplementary Figure 6(a) shows the shift in resonant frequency of an example device after each assembly step; tuning the transmit coil to match the resonant shift on the receiver is used to compensate for this shift [53]. Parasitic capacitance of the resonant coil was controlled by adjusting the space between turns; multiple designs were fabricated and tested to find the optimum coil design.…”