Design of a Fully Integrated Inductive Coupling System: A Discrete Approach Towards Sensing Ventricular Pressure

Abstract

In this paper, an alternative strategy for the design of a bidirectional inductive power transfer (IPT) module, intended for the continuous monitoring of cardiac pressure, is presented. This new integrated implantable medical device (IMD) was designed including a precise ventricular pressure sensor, where the available implanting room is restricted to a 1.8 × 1.8 cm2 area. This work considers a robust magnetic coupling between an external reading coil and the implantable module: a three-dimensional inductor and a touch mode capacitive pressure sensor (TMCPS) set. In this approach, the coupling modules were modelled as RCL circuits tuned at a 13.56 MHz frequency. The analytical design was validated by means of Comsol Multiphysics, CoventorWare, and ANSYS HFSS software tools. A power transmission efficiency (PTE) of 94% was achieved through a 3.5 cm-thick biological tissue, based on high magnitudes for the inductance (L) and quality factor (Q) components. A specific absorption rate (SAR) of less than 1.6 W/Kg was attained, which suggests that this IPT system can be implemented in a safe way, according to IEEE C95.1 safety guidelines. The set of inductor and capacitor integrated arrays were designed over a very thin polyimide film, where the 3D coil was 18 mm in diameter and approximately 50% reduced in size, considering any conventional counterpart. Finally, this new approach for the IMD was under development using low-cost thin film manufacturing technologies for flexible electronics. Meanwhile, as an alternative test, this novel system was fabricated using a discrete printed circuit board (PCB) approach, where preliminary electromagnetic characterization demonstrates the viability of this bidirectional IPT design.

Electromagnetic Nanonetworks Beyond 6G: From Wearable and Implantable Networks to On-Chip and Quantum Communication

“…In inductive coupling, a magnetic field between two coils is utilized to carry information [93]. For example, for a micrometric coil system, the expected resonant frequency is in the order of hundreds of MHz [94]. In capacitive coupling, the electric field between two conductors or electrodes is utilized for the exchange of information.…”

Near‐field wireless power transfer used in biomedical implants: A comprehensive review

“…A novel attitude suggested by Sebastian et al. [110], depending on using bidirectional IC‐WPT to implement an integrated system to obtain continuous observation of cardiac pressure. The design (based on an RCL modelling circuit) works at 13.56 MHz resonance tuning.…”

“…The simulation result shows that the transmission efficiency remains stable even if the alignment between the transmitter and the receiver changes. A novel attitude suggested by Sebastian et al [110], depending on using bidirectional IC-WPT to implement an integrated system to obtain continuous observation of cardiac pressure. The design (based on an RCL modelling circuit) works at 13.56 MHz resonance tuning.…”

Powering implanted sensors that monitor human activity using spider‐web coil wireless power transfer

“…To improve the performance of the WPT system (i.e. achieve maximum power and transfer efficiency) for IBMDs, numerous studies have reported different techniques, such as developing novel system topologies [16,17], proposing novel types of transmitting and receiving coils [15,18], improving misalignment conditions [19], and using various frequencies [7]. Delivering power wirelessly is only one part of the IBMD design.…”