Ultrasonically Powered Implantable Devices
Implantable medical devices (IMDs) are an integral component for implementing next-generation therapies for more effective disease management and prevention. Today’s commercial IMDs such as pacemakers, deep brain neurostimulators, and peripheral nerve stimulators are bulky and invasive because of the need for batteries and wired interfaces. Wireless powering and extensive miniaturization of these implants are crucial for eliminating discomfort and the risk of infection for patients. Millimeter (mm) and sub-mm sized implants also have the potential to open up new applications in sensing, stimulation, and drug delivery. Providing sufficient power (100s of µW to a few mWs) to miniature implants located deep inside the body (> 10 cm) is a big technological challenge. In order to address this challenge, we have designed and optimized systems using ultrasound for power transfer.
Ultrasound offers wavelengths comparable to the size of the implant, enabling (i) focusing of energy at the implant, (ii) design of high efficiency mm- or sub-mm-sized harvesters, and (iii) low tissue attenuation, ultimately achieving high link efficiency and safe power transfer.
Our research on IMDs, starting back in 2012, covers the following broad topics:
(1) End-to-end system design of IMDs for specific biomedical applications such as pressure sensing, electrical/optogenetic stimulation, drug delivery, imaging, and artificial sight , , , , 
(2) Optimized design and miniaturization of ultrasonically powered deep-tissue implants , , 
(3) Robust, bi-directional data communication links using US/RF , , , , , 
(4) Packaging and biocompatibility of IMDs 
(5) Development of an ultrasonic transceiver for locating, powering and communicating with the IMDs .
- Prof. Pierre Khuri-Yakub, Electrical Engineering, Stanford University
- Prof. Richard Zare, Chemistry, Stanford University
- Prof. Stephen Felt, Comparative Medicine, Stanford University
- Prof. Justin Annes, Medicine (Endocrinology), Stanford University
- Prof. Tom Soh, Electrical Engineering and Radiology, Stanford University
- Prof. EJ Chichilnisky, Neuorosurgery, Stanford University
- Dr. Matthew R. Myers, FDA
- Dr. Srikanth Vasudevan, FDA
 T. C. Chang, M. J. Weber, J. Charthad, S. Baltsavias, and A. Arbabian, "End-to-End Design of Efficient Ultrasonic Power Links for Scaling towards Sub-Millimeter Implantable Receivers," IEEE Trans. Biomed. Circuits Syst., vol. 12, no. 5, pp. 1100-1111, Oct. 2018.
 A. Sawaby, M. L. Wang, E. So, J.-C. Chien, H. Nan, B. T. Khuri-Yakub, and A. Arbabian, “A Wireless Implantable Ultrasound Array Receiver for Thermoacoustic Imaging,” 2018 Symp. on VLSI Circuits, Honolulu, HI, June 18-22, 2018.
 C. Kang, T. C. Chang, J. Vo, J. Charthad, M. J. Weber, A. Arbabian, and S. Vasudevan, "Long-Term in Vivo Performance of Novel Ultrasound Powered Implantable Devices," Proc. 2018 Int. Conf. IEEE Eng. in Med. Bio., Honolulu, HI, July 17-21, 2018.
 J. Charthad, T. C. Chang, Z. Liu, A. Sawaby, M. J. Weber, S. Baker, F. Gore, S. A. Felt, and A. Arbabian, "A mm-sized wireless implantable device for electrical stimulation of peripheral nerves," IEEE Trans. Biomed. Circuits Syst., vol. 12, no. 2, pp. 257-270, Apr. 2018.
 M. J. Weber, Y. Yoshihara, A. Sawaby, J. Charthad, T. C. Chang, and A. Arbabian, “A miniaturized single-transducer implantable pressure sensor with time-multiplexed ultrasonic data and power links,” IEEE J. Solid-State Circuits, vol. 53, no. 4, pp. 1089-1101, Apr. 2018.
 M. L. Wang, T. C. Chang, T. Teisberg, M. J. Weber, J. Charthad, and A. Arbabian, “Closed-loop ultrasonic power and communication with multiple miniaturized active implantable medical devices,” 2017 IEEE International Ultrasonics Symposium (IUS), Washington, D.C., Sept 6-9, 2017.
 M. L. Wang and A. Arbabian “Exploiting spatial degrees of freedom for high data rate ultrasound communication with implantable devices,” Applied Physics Letters, vol. 111, no. 13, Sept. 2017.
 T. C. Chang, M. L. Wang, and A. Arbabian, “A 30.5 mm3 fully-packaged implantable device with duplex ultrasonic data and power links achieving 95 kbps with < 10-4 BER at 8.5 cm depth,” 2017 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, February 5-9, 2017, pp. 460-461.
 A. Arbabian, T. C. Chang, M. L. Wang, J. Charthad, S. Baltsavias, M. Fallahpour, M. J. Weber, “Sound Technologies, Sound Bodies: medical implants with ultrasonic links,” IEEE Microwave Magazine, vol. 17, no. 12, pp. 39-54, Dec. 2016.
 T. C. Chang, M. J. Weber, M. L. Wang, J. Charthad, B. T. Khuri-Yakub and A. Arbabian, “Design of tunable ultrasonic receivers for efficient powering of implantable medical devices with reconfigurable power loads,” Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on, vol. 63, pp. 1554-1562, Oct. 2016.
 J. Charthad, S. Baltsavias, D. Samanta, T. C. Chang, M. J. Weber, N. Hosseini-Nassab, R. N. Zare, and A. Arbabian, “An ultrasonically powered implantable device for targeted drug delivery,” Engineering in Medicine and Biology Society (EMBC), 2016 38th Annual International Conference of the IEEE, Orlando, August 16-20, 2016.
 M. J. Weber, A. Bhat, T. C. Chang, J. Charthad, and A. Arbabian, “A miniaturized ultrasonically powered programmable optogenetic implant stimulator system,” in IEEE Biomed. Wireless Technol., Networks, Sens. Syst. Top. Conf., Austin, TX, USA, Jan. 2016. 1st Place Best Paper Award
 J. Charthad, M.J. Weber, T. C. Chang, and A. Arbabian, “A mm-sized implantable medical device (IMD) with ultrasonic power transfer and a hybrid bi-directional data link,” IEEE Journal of Solid-State Circuits, vol. 50, no. 8, pp. 1741-1753, Aug. 2015.