Sensor Systems Laboratory

Inventing new technology for sensing, robotics, wireless power, and medical devices

Joshua R. Smith, Ph. D.
Milton and Delia Zeutschel Professor
Allen School of Computer Science and Engineering, University of Washington
Department of Electrical and Computer Engineering, University of Washington

FREED (Free-range Resonant Electrical Energy Delivery)

A tether-free Left Ventricular Assist Device (LVAD)

FREE-D Researchers

Joshua R. Smith Principal Investigator

Alanson Sample, PhD

Ben Waters, PhD


The Free-range Resonant Electrical Energy Delivery (FREE-D) wireless power system uses magnetically coupled resonators to efficiently transfer power across meter distances to an artificial heart, specifically a ventricular assist device (VAD) implanted in the human body. Previously, artificial heart pumps recieved power from a wire through the chest, limiting patient quality of life. In fact nearly 75% of the LVAD patient population experiences Exit Site Infection (ESI) within the first 6 months of implantation. The FREE-D system will cut down on cardiac patients' dangerous infections and improve quality of life.

The FREE-D system is based on the the Wireless Resonant Energy Link (WREL) wireless power transfer technology developed by the UW Sensor Systems Research Group. In the FREE-D system, transmit and receive resonators are tuned to resonate at a specific frequency. The resonator size and shape can be modified to accommodate application specifications, such as room size and patient body geometry. Additionally, an adaptive frequency tracking method can be implemented to achieve maximum power transfer efficiency – upwards of 70% – for nearly any angular orientation over a range of separation distances.

The transmit resonator can be placed in a wearable vest to transmit power to the implanted receive resonator encased in a biocompatible material. The resonators can accommodate variations in patient body types, and can rapidly adapt to any changes in coil orientation and misalignment. A backup battery can supply power to the LVAD in case the wireless power signal is unavailable.

FREE-D Publications

Promise of Unrestricted Mobility with Innovative, Portable Wireless Powering of a Mechanical Circulatory Assist Device", Pramod Bonde, Benjamin Waters, Alanson Sample, Joshua Smith, 92nd AATS Annual Meeting, San Francisco, CA April 28 - May 2, 2012.

Freeing the LVAD Patient from Drivelines Using Wireless Resonant Electrical Transfer", Benjamin Waters, Alanson Sample, Joshua Smith, Pramod Bonde. Society of Thoracic Surgeons 48th Annual Meeting, Fort Lauderdale, FL January 30 - February 1, 2012.

Powering a Ventricular Assist Device (VAD) with the Free-Range Resonant Electrical Energy Delivery (FREE-D) System, Benjamin H. Waters, Alanson P. Sample, Pramod Bonde, Joshua R. Smith, Proceedings of the IEEE , vol.100, no.1, pp.138-49, Jan. 2012.

Awarded the Sezai Innovation Research Award, Promise of unrestricted mobility and freedom with wireless powering of a Ventricular Assist Device (VAD)", Benjamin Waters, Alanson Sample, Joshua Smith, Pramod Bonde, 19th congress of the International Society of Rotary Blood Pumps, Louisville, KY September 8th to 10th, 2011.

Winner of Willem J Kolff/Don B Olsen Award"Innovative Free-range Resonant Electrical Energy Delivery System (FREE-D System) for a Ventricular Assist Device Using Wireless Power", Joshua Smith, Alanson Sample, Benjamin Waters, Yoshiya Toyoda, Robert L Kormos, Pramod Bonde, ASAIO Journal. 57(2):69-105, March/April 2011, p. 102.