Implantable RF Medical Devices: The Benefits of High-Speed Communication and Much Greater Communication Distances in Biomedical Applications

In the early ages of implantable devices, radio frequency (RF) technologies were not commonplace due to the challenges stemming from the inherent nature of biological tissue boundaries. As technology improved and our understanding matured, the benefit of RF in biomedical applications surpassed the implementation challenges and is thus becoming more widespread. The fundamental challenge is due to the significant electromagnetic (EM) effects of the body at high frequencies. The EM absorption and impedance boundaries of biological tissue result in significant reduction of power and signal integrity for transcutaneous propagation of RF fields. Furthermore, the dielectric properties of the body tissue surrounding the implant must be accounted for in the design of its RF components, such as antennas and inductors, and the tissue is often heterogeneous and the properties are highly variable. Additional challenges for implantable applications include the need for miniaturization, power minimization, and often accounting for a conductive casing due to biocompatibility and hermeticity requirements [1]?[3]. Today, wireless technologies are essentially a must have in most electrical implants due to the need to communicate with the device and even transfer usable energy to the implant [4], [5]. Low-frequency wireless technologies face fewer challenges in this implantable setting than its higher frequency, or RF, counterpart, but are limited to much lower communication speeds and typically have a very limited operating distance. The benefits of high-speed communication and much greater communication distances in biomedical applications have spawned numerous wireless standards committees, and the U.S. Federal Communications Commission (FCC) has allocated numerous frequency bands for medical telemetry as well as those to specifically target implantable applications. The development of analytical models, advanced EM simulation software, and representative RF human phantom recipes has significantly facilitated design and optimization of RF components for implantable applications.

[1]  Sudipto Chakraborty,et al.  Fully Wireless Implantable Cardiovascular Pressure Monitor Integrated with a Medical Stent , 2010, IEEE Transactions on Biomedical Engineering.

[2]  K. Yee.  Numerical solution of initial boundary value problems involving maxwell's equations in isotropic media , 1966 .

[3]  William J. Chappell,et al.  Sub-cubic millimeter intraocular pressure monitoring implant to enable genetic studies on pressure-induced neurodegeneration , 2010, 2010 Annual International Conference of the IEEE Engineering in Medicine and Biology.

[4]  W.J. Chappell,et al.  Implantable Wireless Telemetry Boards for In Vivo Transocular Transmission , 2008, IEEE Transactions on Microwave Theory and Techniques.

[5]  R. Luebbers,et al.  The Finite Difference Time Domain Method for Electromagnetics , 1993 .

[6]  Pedro P Irazoqui,et al.  Toward an implantable wireless cardiac monitoring platform integrated with an FDA-approved cardiovascular stent. , 2009, Journal of interventional cardiology.

[7]  R. W. Lau,et al.  The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues. , 1996, Physics in medicine and biology.

[8]  Sudipto Chakraborty,et al.  Mixed-signal integrated circuits for self-contained sub-cubic millimeter biomedical implants , 2010, 2010 IEEE International Solid-State Circuits Conference - (ISSCC).

[9]  S. Pettersson,et al.  Artificial pacemaker for treatment of Adams-Stokes syndrome and slow heart rate☆ , 1963 .

[10]  Anders J Johansson.  Wave-propagation from medical implants-influence of body shape on radiation pattern , 2002, Proceedings of the Second Joint 24th Annual Conference and the Annual Fall Meeting of the Biomedical Engineering Society] [Engineering in Medicine and Biology.

[11]  K. Paulsen,et al.  Finite element computations of specific absorption rates in anatomically conforming full-body models for hyperthermia treatment analysis , 1993, IEEE Transactions on Biomedical Engineering.

[12]  Hoi-Jun Yoo,et al.  A 490uW fully MICS compatible FSK transceiver for implantable devices , 2009, 2009 Symposium on VLSI Circuits.

[13]  Arthur L. Chlebowski,et al.  A Miniature-Implantable RF-Wireless Active Glaucoma Intraocular Pressure Monitor , 2010, IEEE Transactions on Biomedical Circuits and Systems.

[14]  Brian P. Otis,et al.  A Sub-100 $\mu$ W MICS/ISM Band Transmitter Based on Injection-Locking and Frequency Multiplication , 2011, IEEE Journal of Solid-State Circuits.

[15]  Balwant Godara,et al.  UWB for in-body medical implants: A viable option , 2010, 2010 IEEE International Conference on Ultra-Wideband.

[16]  C.M. Furse,et al.  Design of implantable microstrip antenna for communication with medical implants , 2004, IEEE Transactions on Microwave Theory and Techniques.

[17]  C Gabriel,et al.  The dielectric properties of biological tissues: I. Literature survey. , 1996, Physics in medicine and biology.

[18]  P.P. Irazoqui,et al.  High Data-Rate 6.7 GHz Wireless ASIC Transmitter for Neural Prostheses , 2007, 2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[19]  O. Aquilina,et al.  A brief history of cardiac pacing , 2006, Images in paediatric cardiology.

[20]  Anantha Chandrakasan,et al.  A 350μW CMOS MSK transmitter and 400μW OOK super-regenerative receiver for Medical Implant Communications , 2009, 2008 IEEE Symposium on VLSI Circuits.

[21]  R. W. Lau,et al.  The dielectric properties of biological tissues: II. Measurements in the frequency range 10 Hz to 20 GHz. , 1996, Physics in medicine and biology.

[22]  Eric Kerherve,et al.  A fast and accurate automatic matching network designed for ultra low power medical applications , 2009, 2009 IEEE International Symposium on Circuits and Systems.

[23]  W.J. Chappell,et al.  Evaluation of Cardiovascular Stents as Antennas for Implantable Wireless Applications , 2009, IEEE Transactions on Microwave Theory and Techniques.

[24]  M. R. Yuce,et al.  Easy-to-Swallow Wireless Telemetry , 2012, IEEE Microwave Magazine.

[25]  Donglin Su,et al.  Design of an Ultra Wideband System for In-Body Wireless Communications , 2006, The 2006 4th Asia-Pacific Conference on Environmental Electromagnetics.

[26]  Y. Rahmat-Samii,et al.  Implanted antennas inside a human body: simulations, designs, and characterizations , 2004, IEEE Transactions on Microwave Theory and Techniques.

[27]  P. Irazoqui,et al.  Wireless Powering and the Study of RF Propagation Through Ocular Tissue for Development of Implantable Sensors , 2011, IEEE Transactions on Antennas and Propagation.

[28]  G Hartsgrove,et al.  Simulated biological materials for electromagnetic radiation absorption studies. , 1987, Bioelectromagnetics.

[29]  S. Curto,et al.  DETUNING STUDY OF IMPLANTABLE ANTENNAS INSIDE THE HUMAN BODY , 2012 .

[30]  William J. Chappell,et al.  High frequency transcutaneous transmission using stents configured as a dipole radiator for cardiovascular implantable devices , 2009, 2009 IEEE MTT-S International Microwave Symposium Digest.

[31]  William J. Chappell,et al.  Miniature antenna for RF telemetry through ocular tissue , 2008, 2008 IEEE MTT-S International Microwave Symposium Digest.

[32]  Pedro P. Irazoqui,et al.  Far-Field RF Powering of Implantable Devices: Safety Considerations , 2013, IEEE Transactions on Biomedical Engineering.