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Numerical Thermal Analysis of a Wireless Cortical Implant with Two-Body Packaging

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Abstract

This article presents the numerical analysis of temperature elevation in the head due to the operation of a wireless cortical implant. The thermal analyses are done by using a finite-difference time-domain simulation tool and a high-resolution 3-D head phantom with 22 different tissues. The effects of the power dissipation level, size, location, and packaging of the implant on the temperature distribution in the head are investigated by using a generic silicon chip. Furthermore, the distribution of the power consumption in the implant by using multiple integrated circuits is discussed. In order not to exceed the safety precaution limit of 1°C, maximum allowable power dissipation in a chip of size 2 × 2 × 0.5 mm3 is found to be 5.3 mW, whereas it is 9.3 mW for an implant with two chips of the same size separated by 10 mm. Additionally, the thermal analysis of a wireless cortical implant is also done by using a two-body cortical implant prototype. Maximum allowable power consumption for the two-body implant is found as 35 mW, whereas the unibody implant can only dissipate 17.5 mW without exceeding the safety precaution limit. By using the two-body implant, the maximum allowable power consumption in the implant can be increased or the temperature elevation in the tissues can be decreased.

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Notes

  1. SEMCAD X assigns the temperature of each voxel to the center of that voxel. For example, for a voxel that has grid lines at depth = 0 mm and depth = 0.25 mm, the temperature is assigned to the voxel located at depth = 0.125 mm. This is valid for all three axes.

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Acknowledgements

This work was supported by the Swiss National Funding in the frame of the NEURO-IC project. The authors gratefully acknowledge Schmid & Partner Engineering AG for their help and support for SEMCAD X. The authors thank H. C. Tekin and Prof. M. Gijs from EPFL Microsystems Laboratories for their helps in packaging and G. Yilmaz for his feedbacks.

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  1. Institute of Electrical Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015, Switzerland

    Kanber Mithat Silay, Catherine Dehollain & Michel Declercq

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  1. Kanber Mithat Silay
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  2. Catherine Dehollain
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  3. Michel Declercq
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Correspondence to Kanber Mithat Silay.

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Silay, K.M., Dehollain, C. & Declercq, M. Numerical Thermal Analysis of a Wireless Cortical Implant with Two-Body Packaging. BioNanoSci. 1, 78–88 (2011). https://doi.org/10.1007/s12668-011-0009-2

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