Boston University

Optical Characterization and Nanophotonics Laboratory








Opto-Electrical Wireless Neural Stimulators

Members: M. Selim Ünlü


Alumni: David S. Freedman, Alex Higuera, Vianney Jayasinha, Steven Menn, Philipp Stefan Spuhler, Christine Tschoe, Lu Wang, Arthur Che-An Wu


Electrically powered implanted actuators are commonly used for neural tissue micro-stimulation to research treatment of a variety of neurological disorders. Currently, these actuators are being activated by electrical power delivered through electrodes tethered to the skull, resulting in tissue damage for long-term implants. Optically powered silicon photodiodes can electrically stimulate neural tissue without causing tissue damage. At the near-infrared range of 850nm, an optical power source can safely penetrate human tissue. We have designed and fabricated silicon photodiodes for implantation and opto-electrical stimulation of neural tissue to meet both electrical performance and tissue biocompatibility demands. Having shown successful performance characteristics in the first round of device development, a second round of optimized photodiodes with smaller dimensions and improved stimulation performance have been designed and are currently being fabricated. These devices are expected to facilitate advancements in the study of neurological disease treatment.


M. Sahin, M. S. Ünlü, D. S. Freedman, and A. Abdo, "SYSTEM AND METHOD FOR NEURAL STIMULATION VIA OPTICALLY ACTIVATED FLOATING MICRODEVICES," United States Patent Issued, No. US 9,526,904 B2, 27 December 2016

L. Wang, D. S. Freedman, M. Sahin, M. S. Ünlü, and R. W. Knepper, "Active C4 Electrodes for Local Field Potential Recording Applications," Sensors, Vol. 16, No. 2, 4 February 2016, pp. 198

A. Ersen, S. Elkabes, D. S. Freedman, and M. Sahin, "Chronic tissue response to untethered microelectrode implants in the rat brain and spinal cord," Journal of Neural Engineering, Vol. 12, No. 1, 21 January 2015, pp. 016019

E. Cevik, D. S. Freedman, M. Gökkavas, E. Özbay, M. Sahin, and M. S. Ünlü, "Improved selectivity from a wavelength addressable device for wireless stimulation of neural tissue," Frontiers in Neuroengineering, Vol. 7, No. 00005, 18 February 2014, pp. 1-12

D. S. Freedman, M. Sahin, and B. C. Towe, "Wireless Microstimulators," Encyclopedia of Computational Neuroscience, November 2013

S. Ahn, D. D. Sevenler, and M. R. Monroe, "Biosensors - Innovations in nanobiosensing and biophotonics at Boston University," Boston University, August 2013

A. Abdo, M. Sahin, D. S. Freedman, E. Cevik, P. S. Spuhler, and M. S. Ünlü, "Floating light-activated microelectrical stimulators tested in the rat spinal cord," Journal of Neural Engineering, Vol. 8, No. 5, October 2011

D. S. Freedman, P. S. Spuhler, E. Cevik, M. S. Ünlü, and M. Sahin, "Addressable Floating Light Activated Micro-Electrical Stimulators for Wireless Neurostimulation," 5th International IEEE EMBS Conference on Neural Engineering, 29 April 2011

A. Abdo, M. Sahin, D. S. Freedman, E. Cevik, P. S. Spuhler, and M. S. Ünlü, "Intraspinal Stimulation with Light Activated Micro-Stimulators," 5th International IEEE EMBS Conference on Neural Engineering, 29 April 2011

A. Abdo, M. Sahin, P. S. Spuhler, A. C. Wu, V. Jayasinha, and M. S. Ünlü, "Floating Light Activated Micro-Electrical Stimulators," Neural Interfaces Conference, Cleveland OH, 16-18 June 2008


Mesut Sahin and Ammar Abdo of New Jersey Institute of Technology


National Institute of Health

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