Abstract
Electrical stimulation has been used in a wide variety of medical implant applications. In all of these applications, due to safety concerns, maintaining charge balance becomes a critically important issue that needs to be addressed at the design stage. It is important that charge balancing schemes be robust to circuit (process) and load impedance variations, and at the same time must also lend themselves to miniaturization. In this communication, simulation studies on the effectiveness of using Proportional Integral (P-I) control schemes for managing charge balance in electrical stimulation are presented. The adaptation of the P-I control scheme to implant circuits leads to two possible circuit realizations in the analog domain. The governing equations for these realizations are approximated to simple linear equations. Considering typical circuit and tissue parameter values and their expected uncertainties, Matlab as well as circuit simulations have been carried out. Simulation results presented indicate that the tissue voltages settle to well below 20% of the safe levels and within about 20 stimulations cycles, thus confirming the validity and robustness of the proposed schemes.
References
Sit J J and Sarpeshkar R 2007 A low-power blocking-capacitor-free charge-balanced electrode-stimulator chip with less than 6 nA DC error for 1-mA full-scale stimulation. IEEE Trans. Biomed. Circuits Syst. 1(3): 172–183, doi: 10.1109/TBCAS.2007.911631
Sooksood K, Stieglitz T and Ortmanns M 2010 An active approach for charge balancing in functional electrical stimulation. IEEE Trans. Biomed. Circuits Syst. 4(3): 162–170, doi: 10.1109/TBCAS.2010.2040277
Jiang D, Demosthenous A, Perkins T, Liu X and Donaldson N 2011 A stimulator ASIC featuring versatile management for vestibular prostheses. Biomed. Circuits Syst. IEEE Trans. 5(2): 147–159 doi: 10.1109/TBCAS.2011.2138139
Li Y T, Chen J J, Chen L T, Lin W S, Chu C H 2012 Wireless implantable biomicrosystem for bladder pressure monitoring and nerve stimulation. In: Biomedical circuits and systems conference (BioCAS), 2012 IEEE, pp 296–299, doi: 10.1109/BioCAS.2012.6418438
Cogan S F 2008 Neural stimulation and recording electrodes. Ann. Rev. Biomed. Eng. 10 (1): 275–309, doi: 10.1146/annurev.bioeng.10.061807.160518, pMID: 18429704
Sooksood K, Stieglitz T and Ortmanns M 2009 An experimental study on passive charge balancing. Adv. Radio Sci. 7 (15): 197–200
Lee E K F, Lam A 2007 A matching technique for biphasic stimulation pulse. IEEE international symposium on circuits and systems, pp 817–820, doi: 10.1109/ISCAS.2007.378031
Fang X, Wills J, Granacki J, LaCoss J, Choma J 2008 CMOS charge-metering microstimulator for implantable prosthetic device. MWSCAS 2008 51st Midwest symposium on circuits and systems, pp 826–829, doi: 10.1109/MWSCAS.2008.4616927
Ortmanns M, Rocke A, Gehrke M and Tiedtke H 2007 A 232-channel epiretinal stimulator ASIC. IEEE J. Solid-State Circuits 42(12): 2946–2959, doi: 10.1109/JSSC.2007.908693
Zheng L, Shin S, Kang S 2012 Design of a neural stimulator system with closed-loop charge cancellation. In: VLSI and System-on-Chip (VLSI-SoC), 2012 IEEE/IFIP 20th international conference on, IEEE, pp 1–6
Lo Y K, Hill R, Chen K, Liu W 2013 Precision control of pulse widths for charge balancing in functional electrical stimulation. In: (NER) 6 th international IEEE/EMBS conference on neural engineering, pp 1481–1484, doi: 10.1109/NER.2013.6696225
Chu J U, Song K I, Shon A, Han S, Lee S H, Kang J Y, Hwang D, Suh J K F, Choi K and Youn I 2013 Feedback control of electrode offset voltage during functional electrical stimulation. J. Neurosci. Methods 218 (1): 55–71, doi: 10.1016/j.jneumeth.2013.05.003, http://www.sciencedirect.com/science/article/pii/S0165027013001775
Zeng F G, Rebscher S, Harrison W, Sun X and Feng H 2008 Cochlear implants: System design, integration, and evaluation. IEEE Rev. Biomed. Eng. 1: 115–142 doi: 10.1109/RBME.2008.2008250
Jiang D, Demosthenous A, Cirmirakis D, Perkins T, Donaldson N 2010 Design of a stimulator asic for an implantable vestibular neural prosthesis. In: Biomedical circuits and systems conference (BioCAS), 2010 IEEE, pp 206–209, doi: 10.1109/BIOCAS.2010.5709607
Guo S, Lee H, Loizou P 2008 A 9-bit configurable current source with enhanced output resistance for cochlear stimulators. In: Custom integrated circuits conference, 2008. CICC 2008. IEEE, pp 511–514, doi: 10.1109/CICC.2008.4672134
Noorsal E, Sooksood K, Xu H, Hornig R, Becker J and Ortmanns M 2012 A neural stimulator frontend with high-voltage compliance and programmable pulse shape for epiretinal implants. IEEE J. Solid-State Circuits 47(1): 244–256, doi: 10.1109/JSSC.2011.2164667
Acknowledgements
The author would like to thank Dr. P.V. Ramakrishna, Department of ECE, College of Engineering, Guindy for his guidance at various stages and insightful comments that greatly helped to improve on the results.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
RATHNA, C. PI controller scheme for charge balance in implantable electrical stimulators. Sadhana 41, 31–45 (2016). https://doi.org/10.1007/s12046-016-0461-3
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12046-016-0461-3