Saad  Mutashar, Ahmed S.  Ezzulddin, 
    Design and Implementation of an Efficient Bio-Implantable
Planar Spiral Stacked Coil,
    Journal of Engineering and Applied Sciences,
    Volume 14,Issue 20,
    2019,
    Pages 7636-7646,
    ISSN 1816-949x,
    jeasci.2019.7636.7646,
    (https://makhillpublications.co/view-article.php?doi=jeasci.2019.7636.7646)
    Abstract: This study deals with the design of an efficient small-sized bio-implantable planar spiral square
stacked coils (double layer) based on inductive coupling links technique. The parasitic capacitances of the
proposed design is insignificant, hence, the tuning capacitor of the equivalent circuit can be negligible.
The external coil placed outside the human body with outer dimensions d<sub>out</sub> = 30 mm and inner dimension 
d<sub>in</sub> = 7.6 mm with 15 number of turns. The internal double layer is designed to be inserted within human tissue 
and having outer dimensions d<sub>out</sub> = 10 mm and inner dimension d<sub>in</sub> = 7.6 mm with 3 number of turns for each 
layer. The High Frequency Structural Simulator (HFSS 14.1) is used to design and simulate the coils in the air
and within the phantom human tissue. Mathematical formulas, simulation and experimental results are
introduced to validate the proposed design. The results show that the stacked coils with double layer have
better efficiency than single layer by 2.7% on air and 9.71% within the phantom tissue. The results also,
validated by compression with other previous researcher. To prove that the proposed double layer coil cannot
damage the human tissue the SEMCAD 16.4 Software is used. The proposed design is suitable for implantable
medical devices such as a nerves stimulators.
    Keywords: Implantable medical devices;ISM band;inductive coupling link;planar spiral coils;HFSS Software;insignificant