<figure><img src="image_1.png" /></figure>

Poster ID:

1.2.2

Contact e-mail:

christophe.baron@ens-paris-saclay.fr

# Adaptation of a solid-state marx modulator for
electroactive polymer

Christophe Baron (1), Guojun Lan (1), Yiming Wei (1), Yoan Civet (2), Yves Perriard (2), Martino Lobue (1),
Morgan Almanza (1)

(1) Université Paris-Saclay, ENS Paris-Saclay, CNRS, SATIE, 91190 Gif-sur-Yvette, France, (2) Integrated Actuators Laboratory, École polytechnique fédérale de Lausanne (EPFL) Neuchâtel, Switzerland

## Abstract

Electroactive polymers show promising characteristics, such as lightness, compactness, flexibility, and large displacements, making them a candidate for application in cardiac assist devices [1], robotics and other compact applications. This revives the need for quasi-square wave voltage supply switching between 0 and several kilovolts. It must be efficient in both the charge and discharge phases [2] and compact. The high access resistance, associated with compliant electrodes, represents an additional difficulty. Here, a solid-state Marx modulator is adapted to cope with electroactive polymer characteristics, taking advantage of an efficient energy transfer over a sequential multistep charge/discharge process. To ensure compactness, efficiency, as well as the needs of an implanted device, a wireless magnetic field-based communication and power transfer system has been implemented. This work demonstrates the benefit of this design through simulations and experimental validation on a cardiac assist device. At a voltage of 7 kV, an overall efficiency of up to 88% has been achieved over a complete charge/discharge cycle.

## Introduction

The main focus of this work is on showing the benefits of using a solid-state Marx modulator coupled with a last generation DEA in the framework of biomedical applications. That is why, rather than the converter efficiency for a fixed output voltage, we study the overall efficiency of the converter-DEA chain (mechanical output over the energy supply to the converter) over a full charge/discharge cycle.

Energy transfer to a capacitive load ($E_C$) compared to the one transfer to the resistor ($E_R$) during the time T :

$$ \frac{E_C}{E_R} = \frac{T}{2RC} \frac{I_{\text{mean}}^2}{I_{\text{RMS}}^2} $$

We want $\frac{I_{\text{mean}}^2}{I_{\text{RMS}}^2}$ as high as possible.

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Simple electrical model of a DEA

## Adapted marx generator: from single to multistep charging and discharging

### Wireless power transfer & Communication

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A solid-state Marx modulator is made of N levels. Each level is composed by :

* A capacitor $C_k$

* A diode $D_k$

* Two MOSFETS $LS_k$ and $HS_k$

When $LS_k$ are on and $HS_k$ are off, the capacitor are connected in parallel. In the opposite the capacitors are connected in series.

<figure><img src="image_4.png" /></figure>

## Experimental realisation and results

A solid-state Marx modulator of 24 levels is made [3]. A square root distribution of the capacitance is used to optimized the efficiency.

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DEA's voltage $V_{DEA}$, and current $i_{DEA}$ along a cycle.

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DEA's voltage $V_{DEA}$, and current $i_{DEA}$ along a cycle. Continuous, and dashed lines show the measured, and simulated data respectively. The x-axis has been dilated in correspondence to the charge, and discharge processes in order to better appreciate their multistep structure.

## Conclusion

A multilevel Marx generator has been adapted as an efficient, and low volume way to supply a low power DEA at voltage up to 12.5 kV. A 24 level experimental demonstrator charging a DEA up to 7 kV is presented and fully characterized. The proposed setup reaches an excellent overall efficiency, up to 88%.

The beyond state-of-the-art efficiency, the limited volume, and the wireless control/power design all make the presented setup a possible candidate for implanted cardiac assist devices with a pretty high technology readiness level.

## Acknowledgments

This work has benefited from the financial support of the Werner-Siemens foundation.

## References

[1] M. Almanza, F. Clavica, J. Chavanne, D. Moser, D. Obrist, T. Carrel, Y. Civet, and Y. Perriard, "Feasibility of a dielectric elastomer augmented aorta," Advanced Science, vol. n/a, p. 2001974, 2021.

[2] B. Rechenbach, M. Willatzen, and B. Lassen, "Theoretical study of the electromechanical efficiency of a loaded tubular dielectric elastomer actuator," Applied Mathematical Modelling, 2016

[3] M. Almanza, T; Martinez, M. Petit, Y. Civet, Y. Perriard, M. Lobue, " Adaptation of a solid-state-Marx modulator for electroactive polymer ". IEEE Transactions on Power Electronics, 2022

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