School of Electrical and Computer Engineering
Text Box: A Multi-Carrier Wireless Link for Implantable Biomedical Devices Text Box: An inductive link between two magnetically-coupled coils that constitute a transformer is the most common method to wirelessly transmit power and data to implantable biomedical devices that have relatively high power consumption such as neuromuscular stimulators, cochlear implants, and visual prostheses. Neuroprostheses that substitute sensory functions also need sizeable amounts of real-time data to interface with a large number of neurons by means of tens to hundreds of stimulating sites that are driven simultaneously through multiple parallel channels. The wireless link should be robust enough not to be affected by patient’s motion artifacts or minor coils misalignments. A back telemetry link is also needed for implant power regulation, stimulating sites impedance measurement, and recording the neural response for accurate electrode placement and stimulation parameter adjustments. Therefore, high power transmission efficiency, high data transmission bandwidth, magnetic coupling insensitivity, and back telemetry are the major wireless link requirements in the design and implementation of high performance implantable biomedical devices. While these requirements are individually attainable, they have not been achieved concurrently with traditional techniques. The reason is that there are conflicting constraints involved in achieving high performance in two or more of the above system requirements. Text Box: The research presented here is aimed at developing a robust, power-efficient, wideband, bidirectional wireless link using multiple carrier frequencies. The new link will be utilized in development of a prototype neuroprosthetic testbed for a visual prosthesis. The prototype neuroprosthesis will be tested in vitro to evaluate the multi-frequency wireless link performance in the tissue environment. Then it will be used in short term in vivo experiments. Text Box: Related Publications: F. Inanlou, M. Kiani, and M. Ghovanloo, “A 10.2 Mbps pulse harmonic modulation based transceiver for implantable medical devices,” Accepted for publication in IEEE J. Solid-State Circuits, Mar. 2011. F. Inanlou and M. Ghovanloo, “Wideband near-field data transmission using pulse harmonic modulation,” IEEE Trans. on Circuits and Systems I, vol. 58, no. 1, pp. 186-195, Jan. 2011. F. Inanlou, M. Kiani, and M. Ghovanloo, “A novel pulse-based modulation technique for wideband low power communication with neuroprosthetic devices,” Proc. IEEE 32nd Eng. in Med. and Biol. Conf., pp. 5326-5329, Sep. 2010. U. Jow and M. Ghovanloo, “Optimization of data coils in a multiband wireless link for neuroprosthetic implantable devices,” IEEE Trans. on Biomed. Circuits and Systems, vol. 4, no. 5, pp. 301-310, Oct. 2010. U. Jow and M. Ghovanloo, “Modeling and optimization of printed spiral coils in air, saline, and muscle tissue environments,” IEEE Trans. on Biomed. Circuits and Systems, vol. 3, no. 5, pp. 339-347, Oct. 2009. U. Jow and M. Ghovanloo, “Modeling and Optimization of Printed Spiral Coils in Air and Muscle Tissue Environments,” Proc. IEEE 31st Eng. in Med. and Biol. Conf., pp. 6387-6390, Sep. 2009. U. Jow and M. Ghovanloo, “Optimization of a multiband wireless link for neuroprosthetic implantable devices,” Proc. IEEE Biomed. Circuits and Systems, pp. 97-100, Nov. 2008. U. Jow and M. Ghovanloo, “Design and optimization of printed spiral coils for efficient transcutaneous inductive power transmission,” IEEE Trans. on Biomed. Circuits and Systems, vol. 1, no. 3, pp. 193-202, Sep. 2007. M. Ghovanloo and S. Atluri, “A wideband power-efficient inductive wireless link for implantable microelectronic devices using multiple carriers,” IEEE Trans. on Circuits and Systems I, vol. 54, no. 10, pp. 2211-2221, Oct. 2007. U. Jow and M. Ghovanloo, “Design and optimization of printed spiral coils for efficient inductive power transmission,” Proc. IEEE Intl. Conf. Elec., Circuits and Systems, pp. 70-73, Dec. 2007. S. Atluri and M. Ghovanloo, “A wideband power-efficient inductive wireless link for implantable biomedical devices using multiple carriers,” IEEE Intl. Symp. on Circuits and Systems, pp. 1131-1134, May 2006. S. Atluri and M. Ghovanloo, “Design of a wideband power-efficient inductive wireless link for implantable biomedical devices using multiple carriers,” Proc. 2nd Intl. IEEE/EMBS Conf. on Neural Engineering, pp. 533-537, Mar. 2005. Text Box: Measurement setup: A network analyzer is used to measure coupling coefficients between a pair of planar spiral power

© 2012 Maysam Ghovanloo
Text Box: The wireless link operating frequency, also known as the carrier frequency, is one of the most important parameters of an inductive link, which affects all other system specifications. Traditionally, a single carrier frequency has been used for (1) inductive power transmission, (2) forward data transmission from outside to the implanted device, and (3) back telemetry from the implanted device outward. In this research we are using three carrier signals at three different frequencies and amplitude levels: (a) low-frequency high-amplitude (fP < 1MHz) for power transmission, (b) medium-frequency medium-amplitude (fFD ~ 50MHz) for forward data link, and (c) high-frequency low-amplitude (fBT > 400MHz) for back telemetry. These frequencies are optimal for the above three major functions and we can effectively isolate many of the competing parameters in the design of a wireless link. Therefore, we expect to achieve a high performance in all of the aforementioned system requirements. Text Box: Multi Carrier Measurements: Two individual carriers have been used for power (VPr at 1 MHz) and data (VFDr at 5 and 10 Text Box: Fabricated Coils: Orthogonal multicarrier receiver coils have been implemented on printed circuit boards.