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

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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