Power Transfer by Volume Conduction: In Vitro Validated Analytical Models Predict DC Powers Above 1 mW in Injectable Implants

Marc Tudela-Pi,Aracelys Garcia-Moreno,Jesus Minguillon,Antoni Ivorra,Laura Becerra-Fajardo

doi:10.1109/access.2020.2975597

Marc Tudela-Pi, Aracelys Garcia-Moreno + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.2975597

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Abstract

Galvanic coupling, or more precisely volume conduction, has been recently studied by different research groups as a method for intrabody communications. However, only in a very few occasions its use for powering implants has been proposed and proper analyses of such capability are still lacking. We present the development and the in vitro validation of a set of analytical expressions able to estimate the maximum ac and dc powers attainable in elongated implants powered by volume conduction. In particular, the expressions do not describe the complete power transfer channel but the behavior of the implants when the presence of an electric field is assumed. The expressions and the in vitro models indicate that time-averaged powers above 1 mW can be readily obtained in very thin (diameter in vitro models also indicate that the obtained dc power is maximized by delivering the ac field in the form of short bursts rather than continuously. The study results support the use of volume conduction as a safe option to power implants.

Highlights

The in vitro validation, of a set of analytical expressions able to estimate the maximum ac and dc powers attainable in elongated active implantable medical devices (AIMDs) which are powered by volume conduction
DEPENDENCY ON INTER-ELECTRODE DISTANCE AND ON ELECTRODES DIAMETER At f = 5 MHz, for a Specific Absorption Rate (SAR) of 10 W/kg and for the properties of a saline solution that resembles the properties of muscle tissue, Fig. 8 displays a set of results obtained by applying the analytical expressions together with the corresponding validation results using the in vitro setup
This study supports the use of volume conduction as a safe option to power very thin and flexible AIMDs

Summary

Introduction

Research efforts are being carried out for developing the so-called energy harvesters, known as energy scavengers, which may provide electrical energy to AIMDs from energy sources available within the human body; typically from movements and temperature gradients [20], [21]. All these methods require bulky and rigid parts (e.g., piezoelectric crystals or photodiodes) within the implant that are typically much larger than the electronics they feed.

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