Wireless Power Delivery to Flexible Subcutaneous ... - IEEE Xplore

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Jan 26, 2017 - tures, such as flexible and conformal power receiver realizations, and complies well with IEEE C95.1 specific absorption rate safety standards.
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Wireless Power Delivery to Flexible Subcutaneous Implants Using Capacitive Coupling Rangarajan Jegadeesan, Member, IEEE, Kush Agarwal, Student Member, IEEE, Yong-Xin Guo, Senior Member, IEEE, Shih-Cheng Yen, and Nitish V. Thakor, Fellow, IEEE

Abstract— Implantable devices need sustainable wireless powering for safe long-term operations. In this paper, we present a near-field capacitive coupling (NCC)-based wireless powering scheme to transfer power to implants efficiently. By modeling the power link, we identify that the optimal operating frequency of the NCC scheme for subcutaneous power delivery is in the subGHz frequency range. The proposed scheme has desirable features, such as flexible and conformal power receiver realizations, and complies well with IEEE C95.1 specific absorption rate safety standards. The NCC link was designed and tested in a nonhuman primate cadaver, and the experimental results showed that it could safely deliver up to 100 mW of power to an implant with a peak operating efficiency of over 50%. A bending deformation study of the transmitter–receiver patches was also performed to demonstrate the reliability of the NCC powering scheme, in realistic postimplantation scenarios. Our studies validate the NCC method as a safe wireless powering scheme, which can be used as an alternative to the near-field resonant inductive coupling method, for chronic use in subcutaneous implants. Index Terms— Biomedical devices, electric field coupling, flexible, implants, wireless power transfer.

I. I NTRODUCTION IRELESS power transmission (WPT) enables hassle-free usage of implant devices and extends their lifetime, which otherwise is limited by the battery

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Manuscript received April 8, 2016; revised July 29, 2016 and September 27, 2016; accepted October 1, 2016. Date of publication October 21, 2016; date of current version January 26, 2017. This work was supported by the National Research Foundation (NRF), Prime Minister’s Office, Singapore, under Grant NRF-CRP10-2012-01. The work of K. Agarwal was supported under a NUS Research Scholarship. (Rangarajan Jegadeesan and Kush Agarwal are co-first authors.) (Shih-Cheng Yen and Nitish V. Thakor contributed equally to this work.) (Corresponding author: Kush Agarwal.) R. Jegadeesan was with the Singapore Institute for Neurotechnology (SINAPSE), Singapore 117456. He is now with the Engineering Design and Innovation Centre, National University of Singapore, Singapore 117579 (e-mail: [email protected]). K. Agarwal and S.-C. Yen are with the Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117579, and also with the Singapore Institute for Neurotechnology (SINAPSE), Singapore 117456 (e-mail: [email protected]; [email protected]). Y.-X. Guo is with the Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117579, and also with the NUS Suzhou Research Institute, Suzhou 215123, China (e-mail: [email protected]). N. V. Thakor is with the Singapore Institute for Neurotechnology (SINAPSE), Singapore 117456, and also with the Department of Electrical and Computer Engineering, the Department of Biomedical Engineering, and the Department of Medicine, National University of Singapore, Singapore 117579 (e-mail: [email protected]). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMTT.2016.2615623

capacity. Wirelessly powered implants have become the norm with current FDA approved commercial chronic implant devices [1]–[5]. Wireless powering is predominantly done using near-field resonant inductive coupling (NRIC), which traces its roots to works by Faraday [6], Garratt [7], and Tesla [8]. More than 100 years later, the same powering scheme is being used today. Though established and sufficient to meet the powering needs of current implants, the NRIC powering scheme has its own set of limitations. Electrodes and associated electronic components for implantable devices have evolved in the last few years, to have flexible and conformal realizations to suit the implantation needs [9]–[13], while still having minimal or no decline in performance. However, the same cannot be said about the NRIC powering scheme, as it still supports only rigid realizations of coils. This is due to the fact that the NRIC scheme, which induces voltage at the implant side, utilizes coils that resonate at a particular frequency of operation. Even a mild flexion would lead to misalignments that would detune the resonance, leading to a power drop at the implant. Nevertheless, a few attempts have been made to design flexible coils for NRIC, and they all unanimously report considerable power loss (P.L.) under flexion [14]–[16]. Flexible substrates and conductors have been reported in abundance over the last decade [17], [18]. However, NRIC links have not benefited greatly from these developments, owing to the heavy dependence of power transfer efficiency (PTE) on resonance, which cannot be guaranteed under real-time flexion. This calls for a nonresonant method to support flexible conformal realizations. Hence, we analyzed the nonresonant modes of operation of inductive and capacitive power transfer in the context of subcutaneous power links. We found that the capacitive power transfer link has a naturally wide bandwidth, at a frequency band that is high enough to reduce capacitive impedance and low enough to be far from its self-resonance. This large bandwidth makes it possible to accommodate flexion of the conductors (used for transferring power), allowing flexible realizations. We start with this premise of using the nonresonant mode of the capacitive coupling to transfer power using flexible conductor realizations. Wireless power transfer using near-field capacitive coupling (NCC) was initially proposed for industrial applications [19]–[23]. However, due to its limited range and the success of the inductive power transfer links, its adoption

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JEGADEESAN et al.: WIRELESS POWER DELIVERY TO FLEXIBLE SUBCUTANEOUS IMPLANTS USING CAPACITIVE COUPLING

has been limited. Capacitive power transfer for implantable applications was first proposed in [24], and highly efficient NCC links were demonstrated in [25]. Recent work [26] showed NCC links to have better electromagnetic interference (EMI) performance than NRIC links. However, no modeling of NCC links exists for use in implantable devices, and the scheme has never been validated in an actual animal model. In this paper, we developed a theoretical model of the NCC link for implantable applications, to estimate the PTE and optimal operating frequency range, from the basic link parameters (conductor dimensions, separation, and tissue thickness). Based on the model, we propose to use the nonresonant mode of NCC link at an optimum frequency band to achieve two main objectives: 1) transfer power efficiently to the implant and 2) provide good tolerance to real-time flexion. The NCC links were built using flexible conductor patches and were validated to transfer power efficiently in a nonhuman primate (NHP) cadaver. Studies were carried out for the designed NCC links to validate the performance of NCC links under real-time flexion of the conductor patches. To ensure safe operation of the NCC link, safety analysis was carried out and the theoretical results were verified with simulations, performed using finite integration technique-based commercial EM software—CST Microwave Studio [27]. Section II focuses on introducing the fundamentals of the capacitively coupled NCC wireless power transfer scheme. The theoretical modeling of the NCC powering scheme is analyzed in Section III to evaluate the link performance parameters including return loss (R.L.) PTE, and the maximum permissible safe transmitted power limits. Section IV discusses simulation results like reflection coefficient, forward gain |S21 |, specific absorption rate (SAR), and thermal variation obtained from CST Microwave Studio, by analyzing the link performance in a three-layer tissue model. The optimal link fabrication methodology is discussed in Section V. NCC link implementation and performance measurement under normal operation and under flexion in an NHP cadaver are presented in Section VI. Section VII summarizes the results obtained in this paper. II. NCC The NCC scheme is the capacitive counterpart of the NRIC’s inductive scheme. It works on the principle of displacement currents, which need no material medium for the transfer of charges, to enable wireless energy transfer. The power transfer scheme is shown in Fig. 1. The powering scheme comprises of conductors on either side of the skin of tissue thickness D, and the power is transferred via the mutual capacitance between the conductors. Two such capacitances are needed to complete a current loop through which the power is delivered to the load. Since the capacitance, formed by two metallic patches (of implantable dimensions) separated by a few millimeters (5 mm), is small (20%) under flexion for NCC scheme. The NRIC link on the other hand detunes severely due

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TABLE V C OMPARISON B ETWEEN NRIC AND NCC S CHEMES

Under normal operating conditions, both schemes can deliver similar power levels at the implant. The NRIC link has advantages of longer range of power transfer when compared with the NCC links. However, in many of the current day implants [3], [4], the power receivers are positioned just below the skin, which perfectly suits the NCC scheme. Based on our earlier work on inductive coupling [37], [39] and the current work, a comparison has been listed above for the two nearfield WPT schemes for similar implant dimensions in Table V. VII. C ONCLUSION

Fig. 15. Measurement results for three different flexion levels (bending radius = 20, 30, and 40 mm) of the implanted copper RX patches. (a) Reflection coefficient graph. (b) Power delivered to the implant graph (mW) and (c) PTE graph (without considering the reflection losses at the TX input). The reflection coefficient variation is minimal for various degrees of flexion. The TX–RX metallic patches were separated by ∼3 mm thick skin layer of the NHP cadaver.

Flexible subcutaneous implant wireless power delivery using NCC has been presented starting from the theoretical conceptualization and modeling, to the simulations, design implementation, and experiments in NHP animal model. The NCC scheme presents itself as a viable alternative to the traditional NRIC scheme, and supports flexible conformal realizations, making it more suitable for implant applications. CST MWS simulations showed that the NCC method can be safely used to transmit hundreds of milliwatts of power wirelessly to the implant. Our experiments confirm that the PTE is over 50% for a 20 mm × 20 mm realized patch dimension, and has minimal variation in performance, due to flexion deformation. Future work will need to carry out NCC powered implantable devices for practical neuromodulation applications. Further, chronic safety and efficacy would need to be demonstrated in live animal models. Only after these chronic live investigations can we vouch for using capacitively coupled powering scheme for long-term subcutaneous implant applications.

to flexion and operates out of resonance where the efficiencies are below 5% (calculated for a 15 mm × 15 mm implant coil, 5 mm separation, and a bending radius of 10 mm).

The authors would like to thank the engineers, W. D. Sheng and S. Maqsood from the Singapore Institute

ACKNOWLEDGMENT

JEGADEESAN et al.: WIRELESS POWER DELIVERY TO FLEXIBLE SUBCUTANEOUS IMPLANTS USING CAPACITIVE COUPLING

for Neurotechnology, for helping with the experiment preparations, and the veterinarians, A. Chew and G. Gammad from the Singapore Institute for Neurotechnology, for their help with the nonhuman primate experiments. R EFERENCES [1] G. E. Loeb, F J. R. Richmond, and L. Baker, “The BION devices: Injectable interfaces with peripheral nerves and muscles,” Neurosurgical Focus, vol. 20, no. 5, pp. 1–9, 2006. [2] I. Hochmair et al., “MED-EL cochlear implants: State of the art and a glimpse into the future,” Trends Amplification, vol. 10, no. 4, pp. 201–219, 2006. [3] J. F. Patrick, P. A. Busby, and P. J. Gibson, “The development of the nucleus freedom cochlear implant system,” Trends Amplification, vol. 10, no. 4, pp. 175–200, 2006. [4] F. G. Zeng, S. Rebscher, W. Harrison, X. Sun, and H. Feng, “Cochlear implants: System design, integration, and evaluation,” IEEE Rev. Biomed. Eng., vol. 1, pp. 115–142, Jan. 2008. [5] A. T. Chuang, C. E. Margo, and P. B. Greenberg, “Retinal implants: A systematic review,” Brit. J. Ophthalmol, vol. 98, no. 7, pp. 852–856, 2014. [6] M. Faraday, “Experimental researches in electricity,” Philos. Trans., vol. 122, pp. 125–162, Jan. 1832. [7] G. R. M. Garratt, The Early History of Radio: From Faraday to Marconi. IET, 1994, ch. 4, pp. 34–50. [8] N. Tesla, “Apparatus for transmitting electrical energy,” U.S. Patent 1 119 732, May 4, 1907. [9] T. Stieglitz, H. Beutel, and J.-U. Meyer, “A flexible, light-weight multichannel sieve electrode with integrated cables for interfacing regenerating peripheral nerves,” Sens. Actuators A, Phys., vol. 60, nos. 1–3, pp. 240–243, 1997. [10] S. Bossi, S. Kammer, T. Dorge, A. Menciassi, K. P. Hoffmann, and S. Micera, “An implantable microactuated intrafascicular electrode for peripheral nerves,” IEEE Trans. Biomed. Eng., vol. 56, no. 11, pp. 2701–2706, Nov. 2009. [11] D. H. Kim et al., “Silicon electronics on silk as a path to bioresorbable, implantable devices,” Appl. Phys. Lett., vol. 95, no. 13, pp. 1–3, 2009. [12] J. Viventi et al., “A conformal, bio-interfaced class of silicon electronics for mapping cardiac electrophysiology,” Sci. Transl. Med., vol. 2, no. 24, pp. 1–9, 2010. [13] D.-H. Kim et al., “Dissolvable films of silk fibroin for ultrathin conformal bio-integrated electronics,” Nature Mater., vol. 9, pp. 511–517, Apr. 2010. [14] J. G. McCall et al., “Fabrication and application of flexible, multimodal light-emitting devices for wireless optogenetics,” Nature Protocols, vol. 8, pp. 2413–2428, Nov. 2013. [15] A. Qusba, A. K. RamRakhyani, J.-H. So, G. J. Hayes, M. D. Dickey, and G. Lazzi, “On the design of microfluidic implant coil for flexible telemetry system,” IEEE Sensors J., vol. 14, no. 4, pp. 1074–1080, Apr. 2014. [16] S. Xu et al., “Stretchable batteries with self-similar serpentine interconnects and integrated wireless recharging systems,” Nature Commun., vol. 4, pp. 1–8, Feb. 2013. [17] A. Tabatabai, A. Fassler, C. Usiak, and C. Majidi, “Liquid-phase gallium–indium alloy electronics with microcontact printing,” Langmuir, vol. 29, no. 20, pp. 6194–6200, 2013. [18] S. Moreno et al., “Biocompatible collagen films as substrates for flexible implantable electronics,” Adv. Electron. Mater., vol. 1, no. 9, pp. 1–8, 2015. [19] M. Kline, I. Izyumin, B. Boser, and S. Sanders, “Capacitive power transfer for contactless charging,” in Proc. IEEE Appl. Power Electron. Conf. Expo., Mar. 2011, pp. 1398–1404. [20] M. P. Theodoridis, “Effective capacitive power transfer,” IEEE Trans. Power Electron., vol. 27, no. 12, pp. 4906–4913, Dec. 2012. [21] L. Huang and A. P. Hu, “Defining the mutual coupling of capacitive power transfer for wireless power transfer,” Electron. Lett., vol. 51, no. 22, pp. 1806–1807, Oct. 2015. [22] A. Kumar, S. Pervaiz, C.-K. Chang, S. Korhummel, Z. Popovic, and K. K. Afridi, “Investigation of power transfer density enhancement in large air-gap capacitive wireless power transfer systems,” in Proc. IEEE Wireless Power Transf. Conf., 2015, pp. 1–4. [23] H. Zhang, F. Lu, H. Hofmann, W. Liu, and C. C. Mi, “A four-plate compact capacitive coupler design and LCL-compensated topology for capacitive power transfer in electric vehicle charging application,” IEEE Trans. Power Electron., vol. 31, no. 12, pp. 8541–8551, Dec. 2016.

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[24] A. M. Sodagar and P. Amiri, “Capacitive coupling for power and data telemetry to implantable biomedical microsystems,” in Proc. IEEE 4th Int. Conf. Neural Eng., May 2009, pp. 411–414. [25] R. Jegadeesan, Y. X. Guo, and M. Je, “Electric near-field coupling for wireless power transfer in biomedical applications,” in Proc. IEEE MTT-S Int. Microw. Workshop Ser. RF Wireless Technol. Biomed. Healthcare Appl., Dec. 2013, pp. 1–3. [26] A. I. Al-Kalbani, M. R. Yuce, and J.-M. Redoute, “A biosafety comparison between capacitive and inductive coupling in biomedical implants,” IEEE Antennas Wireless Propag. Lett., vol. 13, pp. 1168–1171, 2014. [27] E. Gjonaj, M. Bartsch, M. Clemens, S. Schupp, and T. Weiland, “High-resolution human anatomy models for advanced electromagnetic field computations,” IEEE Trans. Magn., vol. 38, no. 2, pp. 357–360, Mar. 2002. [28] Y. Feldman, A. Puzenko, and Y. Ryabov, “Dielectric relaxation phenomena in complex materials,” in Fractals, Diffusion, and Relaxation in Disordered Complex Systems: Advances in Chemical Physics. Hoboken, NJ, USA: Wiley, 2006. [29] K. R. Foster and H. P. Schwan, “Dielectric properties of tissues and biological materials: A critical review,” Critical Rev. Biomed. Eng., vol. 17, no. 1, pp. 25–104, 1989. [30] S. Gabriel, R. W. Lau, and C. Gabriel, “The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues,” Phys. Med. Biol., vol. 41, no. 11, pp. 2271–2293, 1996. [31] S. Gabriel, R. W. Lau, and C. Gabriel, “The dielectric properties of biological tissues: II. Measurements in the frequency range 10 Hz to 20 GHz, Phys. Med., Biol., vol. 41, no. 11, pp. 2251–2269, 1996. [32] F. E. Terman, Radio Engineers Handbook. New York, NY, USA: McGraw-Hill, 1945. [33] N. O. Sokal and A. D. Sokal, “Class E-A new class of high-efficiency tuned single-ended switching power amplifiers,” IEEE J. Solid-State Circuits, vol. SSC-10, no. 3, pp. 168–176, Jun. 1975. [34] IEEE Standard for Safety Levels With Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz, IEEE Standard C95.1-2005, 2006, pp. 1–238. [35] K. Agarwal and Y.-X. Guo, “Interaction of electromagnetic waves with humans in wearable and biomedical implant antennas,” in Proc. Asia– Pacific Symp. Electromagn. Compat., 2015, pp. 154–157. [36] “Adult reference computational phantoms,” Ann. ICRP, vol. 39, no. 2, 2009. [37] R. Jegadeesan, S. Nag, K. Agarwal, N. V. Thakor, and Y.-X. Guo, “Enabling wireless powering and telemetry for peripheral nerve implants,” IEEE J. Biomed. Health Inf., vol. 19, no. 3, pp. 958–970, May 2015. [38] C. Hassler, T. Boretius, and T. Stieglitz, “Polymers for neural implants,” J. Polymer Sci. B, Polymer Phys. vol. 49, no. 1, pp. 18–33, 2011. [39] R. Jegadeesan and Y.-X. Guo, “Topology selection and efficiency improvement of inductive power links,” IEEE Trans. Antennas Propag., vol. 60, no. 10, pp. 4846–4854, Oct. 2012.

Rangarajan Jegadeesan (M’09) received the bachelor’s degree in electronics and communication engineering from the College of Engineering, Guindy, India, in 2007, and the Ph.D. degree in electrical and computer engineering from the National University of Singapore (NUS), Singapore, in 2014. He was with the Cypress Semiconductor Corporation, as a Product Engineer, where he focused on postsilicon characterization, and later a Systems Engineer, responsible for touch screen and lowpower RF solutions. He joined the Singapore Institute for Neurotechnology, Singapore, in 2014, as a Post-Doctoral Research Fellow, where he was leading the efforts for the development of wireless technologies for implant devices and establishment of regulatory compliance. He is currently a Lecturer with the Engineering Design and Innovation Center, NUS. He is a Registered Professional Consultant with the Multiple Semiconductor Manufacturers on touch screen and RF solutions. His current research interests include antennas, implant technologies, electrical safety, sensors, and low power RF.

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Kush Agarwal (GS’12) received the bachelor’s degree in electronics and telecommunication engineering from the College of Engineering Roorkee, Roorkee, India, in 2010, and the master’s degree in communications engineering from Nanyang Technological University, Singapore, in 2013. He is currently pursuing the Ph.D. degree under the joint supervision of Prof. Y.-X. Guo and Prof. Nitish V. Thakor on a Graduate Research Scholarship at the National University of Singapore (NUS), Singapore. He was a Software Developer with the CGI Group Inc., Montreal, QC, Canada, from 2010 to 2011. He joined the Department of Electrical and Computer Engineering, NUS, in 2012, under the supervision of Prof. Y.-X. Guo for research on wearable and implantable antennas and sensors. He has authored several conference and journal papers in the field of metamaterial-based far-field antennas. He was involved in metamaterial-based circularly polarized antennas at the RF, Antenna, and Optical Department, Institute for Infocomm Research, A*STAR, Singapore. His current research interests include electromagnetics for biomedical implant applications, electrical and biological safety, RF energy harvesting, RFID, and near-field sensing and antennas for various applications. Mr. Kush is a member of the IEEE Antennas and Propagation Society, the IEEE Microwave Theory and Techniques Society, and the IEEE Engineering in Medicine and Biology Society. He was a recipient of the Young Scientist Award from the International Union of Radio Science, in 2012, and the European Microwave Association Student Grants in 2012 and 2013 for attending European Microwave Conferences at Amsterdam, The Netherlands and Nuremberg, Germany, for his master’s research work. Yong-Xin Guo (SM’05) received the B.Eng. and M.Eng. degrees in electronic engineering from the Nanjing University of Science and Technology, Nanjing, China, in 1992 and 1995, respectively, and the Ph.D. degree in electronic engineering from the City University of Hong Kong, Hong Kong, in 2001. From 2001 to 2009, he was a Research Scientist with the Institute for Infocomm Research, Singapore. He joined the Department of Electrical and Computer Engineering, National University of Singapore (NUS), as an Assistant Professor in 2009 and a Tenured Associate Professor in 2013, where he is the Director of the Center for Microwave and Radio Frequency. He is currently a Senior Investigator and the Director of the Center of Advanced Microelectronic Devices, National University of Singapore Suzhou Research Institute (NUSRI), Suzhou, China. He has authored or co-authored 177 international journal papers and 187 international conference papers. His publications have been cited by others more than 2400 times and has an H-index of 31 (source: Scopus). He holds seven granted/filed patents in the U.S. or China. He has graduated seven Ph.D. students at NUS. His current research interests include MMIC modeling and design, RF energy harvesting and wireless power for biomedical applications and Internet of Things, microstrip antennas for wireless communications, implantable/wearable antennas, on-chip antennas, and antennas in package. Dr. Guo was a recipient of the Young Investigator Award at NUS in 2009. He was also a recipient of the Raj Mittra Travel Grant Senior Researcher Award in 2013 and the Best Poster Award in the 2014 International Conference on Wearable and Implantable Body Sensor Networks, Zurich, Switzerland. He was a co-recipient of the Design Contest Award of the 20th International Symposium on Low Power Electronics and Design, Rome, Italy, in 2015. His Ph.D. students received the Best Student Paper Awards from the IEEE MTT-S IMWS-Bio 2015, in Taiwan, the IEEE iWEM 2013 in Hong Kong, the 2011 National Microwave and Millimeter-Wave Conference at Qingdao, China, and the IEEE ICMMT 2010 in Chengdu, China. He is the General Chair of the 2017 International Applied Computational Electromagnetics Society Symposium in Suzhou, China, and was the General Chair of the 2015 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes on RF and THz Applications, Suzhou, and the IEEE MTT-S International Microwave Workshop Series 2013 on “RF and Wireless Technologies for biomedical and Healthcare Applications” in Singapore. He was a Technical Program Committee (TPC) Co-Chair for the IEEE International Symposium on Radio Frequency Integration Technology in 2009. He has been a TPC Member and a Session Chair for numerous conferences and workshops. He is an Associate Editor of the IEEE A NTENNAS AND W IRELESS P ROPAGATION L ETTERS and IET Microwaves, Antennas and Propagation, and Electronics Letters.

Shih-Cheng Yen received the B.S.E., M.S.E., and Ph.D. degrees from the Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA, in 1993 and 1998, respectively, where he was involved in neural network models of the primary visual cortex. He spent several years performing single-neuron recordings in the primary visual cortex of both anesthetized cats and awake behaving nonhuman primates, first as a Post-Doctoral Fellow with the University of California at Davis, Davis, CA, USA, and subsequently as a Research Assistant Professor with Montana State University, Bozeman, MT, USA. He is currently an Assistant Professor with the Department of Electrical and Computer Engineering, National University of Singapore (NUS), Singapore, and the Deputy Director of the Singapore Institute for Neurotechnology at NUS. His current research interests include neural coding and neuroprosthetics.

Nitish V. Thakor (F’94) is the Director of the Singapore Institute for Neurotechnology, National University of Singapore, Singapore, as well as a Professor of biomedical engineering with The Johns Hopkins University, Baltimore, MD, USA. His technical expertise is in the field of neuroengineering, where he has pioneered many technologies for brain monitoring to prosthetic arms and neuroprosthesis. He is currently the Editor-in-Chief of Medical and Biological Engineering and Computing. He is a co-founder of three companies. He has authored 320 refereed journal papers and holds more than a dozen patents. Dr. Thakor is a Fellow of the American Institute of Medical and Biological Engineering, Founding Fellow of the Biomedical Engineering Society, and Fellow of the International Federation of Medical and Biological Engineering. He was a recipient of the Research Career Development Award from the National Institutes of Health, the Presidential Young Investigator Award from the National Science Foundation, the Award of Technical Excellence in Neuroengineering from the IEEE Engineering in Medicine and Biology Society, the Distinguished Alumnus Award from IIT Bombay, Mumbai, India, and a Centennial Medal from the University of Wisconsin School of Engineering. He was the Editor-in-Chief of the IEEE T RANSACTIONS ON N EURAL S YSTEMS AND R EHABILITATION E NGINEERING from 2005 to 2011.