An analysis of the capacitance created in capacitive power transfer devices used for Medical Implants

Zargari, Siamak; Moezzi, Mohsen

doi:10.48301/kssa.2025.466732.2939

An analysis of the capacitance created in capacitive power transfer devices used for Medical Implants

Document Type : Original Article

Authors

Siamak Zargari ¹

Mohsen Moezzi ²

¹ PhD Student, Department of Electrical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.

² Assistant Professor, Department of Electrical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.

10.48301/kssa.2025.466732.2939

Abstract

It is crucial to determine the capacitance that is created when capacitive power transmission is used in a medical implant. In this application, the capacitance is affected by the decrease in size and the proximity of the two capacitor plates, causing it to deviate from the traditional formula. Additionally, the fringing effects bring substantial inaccuracies when determining the final capacitor value. Conformal mapping is commonly employed to compute this capacitance, necessitating specific assumptions that vary based on the particular problem. This work presents a detailed simulation of a capacitor model that incorporates muscular dielectric and biocompatible materials for insulation. The simulation is conducted using Maxwell software and experimental measurement to analyze the capacitance produced between the two capacitor plates. Moreover, this work presents an enhanced equation for determining capacitance in situations where the capacitor plates have limited distances and compact dimensions. The new formula significantly decreases the estimation error of capacitance, reducing it from over 40% to less than 16% when compared to traditional formulas.

Keywords

Capacitive power transfer

Medical Implants

fring capacitor

Parallel plate capacitor

Comformal mapping

Subjects

Electronic

[1] Hamedani, N., & Karimi Moridani, M. (2021). Design and Manufacturing of Gloves for Intelligent Quantification of Hand Vibration. Karafan Journal, 18(3), 79-99. https://doi.org/10.48301/kssa.2021.282479.1489

[2] Sumayli, A. (2021). Recent trends on bioimplant materials: A review. Materials Today: Proceedings, 46, 2726-2731. https://doi.org/10.1016/j.matpr.2021.02.395

[3] Liu, Y., Li, B., Huang, M., Chen, Z., & Zhang, X. (2018). An overview of regulation topologies in resonant wireless power transfer systems for consumer electronics or bio-implants. Energies, 11(7), 1737. https://doi.org/10.3390/en11071737

[4] Maroosi, A., Zabbah, I., Mogharebi, M., Yasrebi, S. e., & Layeghi, K. (2022). Improving Diagnosis of Breast Cancer Disease Using Adaptive Neuro-fuzzy Inference System. Karafan Journal, 19(3), 377-392. https://doi.org/10.48301/kssa.2022.277156.1426

[5] Hossain, A. S., Mohseni, P., & Lavasani, H. M. (2022). Design and optimization of capacitive links for wireless power transfer to biomedical implants. IEEE Transactions on Biomedical Circuits and Systems, 16(6), 1299-1312. https://doi.org/10.1109/TBCAS.2022.3213000

[6] Chou, N., Moon, H., Park, J., & Kim, S. (2021). Interfacial and surface analysis of parylene C-modified PDMS substrates for soft bioelectronics. Progress in Organic Coatings, 157, 106309. https://doi.org/10.1016/j.porgcoat.2021.106309

[7] Masoumnezhad, M. (2024). Fabrication of Polyaniline Electrode Using Nickel Foam Substrate for Use in Supercapacitors Electrode. Karafan Journal, 21(1), 321-333. https://doi.org/10.48301/kssa.2024.431988.2794

[8] Nguyen, Q. P. (2011). Characterization of biocompatible parylene-C coating for BioMEMS applications. Louisiana State University and Agricultural & Mechanical College. https://doi.org/10.31390/gradschool_theses.1478

[9] Lazzi, G. (2005). Thermal effects of bioimplants. IEEE Engineering in Medicine and Biology Magazine, 24(5), 75-81. https://doi.org/10.1109/MEMB.2005.1511503

[10] Feng, Y., Zhou, Z., Wang, W., Rao, Z., & Han, Y. (2021). The 3D capacitance modeling of non-parallel plates based on conformal mapping. 2021 IEEE 16th International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), https://doi.org/10.1109/NEMS51815.2021.9451427

[11] Schinzinger, R., & Laura, P. A. (2012). Conformal mapping: methods and applications. Courier Corporation. https://scispace.com/pdf/conformal-mapping-methods-and-applications-20zmd88z1o.pdf

[12] Muratori, B., Jones, J., & Wolski, A. (2015). Analytical expressions for fringe fields in multipole magnets. Physical Review Special Topics-Accelerators and Beams, 18(6), 064001. https://doi.org/10.1103/PhysRevSTAB.18.064001

[13] Palmer, H. B. (1937). The capacitance of a parallel-plate capacitor by the Schwartz-Christoffel transformation. Electrical Engineering, 56(3), 363-368. https://doi.org/10.1109/EE.1937.6540485

[14] Elliott, R. (1966). Relativity and electricity. IEEE spectrum, 3(3), 140-152. https://doi.org/10.1109/MSPEC.1966.5216743

[15] Elsaadi, M., Tayel, M. B., & Steenson, D. (2021). An Empirical Formula of Fringing Field Capacitance for MEMS Tunable Capacitor Actuators. 2021 IEEE 1st International Maghreb Meeting of the Conference on Sciences and Techniques of Automatic Control and Computer Engineering MI-STA, https://doi.org/10.1109/MI-STA52233.2021.9464509

[16] Sakurai, T., & Tamaru, K. (1983). Simple formulas for two-and three-dimensional capacitances. IEEE Transactions on Electron Devices, 30(2), 183-185. https://doi.org/10.1109/T-ED.1983.21093

[17] Van Der Meijs, N., & Fokkema, J. (1984). VLSI circuit reconstruction from mask topology. Integration, 2(2), 85-119. https://doi.org/10.1016/0167-9260(84)90016-6

[18] Sloggett, G., Barton, N., & Spencer, S. (1986). Fringing fields in disc capacitors. Journal of Physics A: Mathematical and General, 19(14), 2725. https://doi.org/10.1088/0305-4470/19/14/012

[19] Cooke, J. (1958). The coaxial circular disc problem. ZAMM‐Journal of Applied Mathematics and Mechanics/Zeitschrift für Angewandte Mathematik und Mechanik, 38(9‐10), 349-356. https://doi.org/10.1002/zamm.19580380904

[20] Wu, X., Zhao, W., Duan, J., Qu, Z., Wang, J., & Zhang, B. (2022). Flexible pressure sensor based on graphene/PS microsphere/PDMS composite dielectric layer and activated carbon non-woven fabrics. Materials Letters, 326, 132952. https://doi.org/10.1016/j.matlet.2022.132952

[21] (IT'IS), T. F. f. R. o. I. T. i. S. (2022). https://itis.swiss/virtual-population/tissue-properties/database/dielectric-properties

[22] Dodd, S., Bassi, A., Bodger, K., & Williamson, P. (2006). A comparison of multivariable regression models to analyse cost data. Journal of evaluation in clinical practice, 12(1), 76-86. https://doi.org/10.1111/j.1365-2753.2006.00610.x

[23] Strutz, T. (2011). Data fitting and uncertainty: A practical introduction to weighted least squares and beyond (Vol. 1). Springer. https://link.springer.com/book/9783658114558

[24] Yang, H.-C., Chi, S.-C., & Liao, W.-S. (2022). Comparison of Fitting Current–Voltage Characteristics Curves of FinFET Transistors with Various Fixed Parameters. Applied Sciences, 12(20), 10519. https://doi.org/10.3390/app122010519

[25] Zhuang, H., Nelson, S., Trabelsi, S., & Savage, E. (2007). Dielectric properties of uncooked chicken breast muscles from ten to one thousand eight hundred megahertz. Poultry Science, 86(11), 2433-2440. https://doi.org/10.3382/ps.2006-00434