Feasibility Study on Active Back Telemetry and Power Transmission Through an Inductive Link for Millimeter-Sized Biomedical Implants

• Published in: IEEE transactions on biomedical circuits and systems 2017-12, Vol.11 (6), p.1366-1376
• Main Authors: Yeon, Pyungwoo, Mirbozorgi, S. Abdollah, Lim, Jaemyung, Ghovanloo, Maysam
• Format: Article
• Language: English
• Subjects: Bit error rate; Brain; Brain models; Circuit design; Coils; Couplings; Data transmission; Design optimization; Equipment Design; Feasibility studies; Floating structures; Free-floating neural interfacing probes; Implants; Medical devices; mm-sized implantable medical devices; Neural networks; Power efficiency; Power transmission; Prostheses and Implants; pulse-based near-field transceiver; Surgical implants; Telemetry; Telemetry - methods; Tissues; Transmission circuits; Transmission efficiency; Transplants & implants; Wireless communication; Wireless power transmission; wireless power/data transmission; Wireless Technology - instrumentation
• ISSN: 1932-4545; 1940-9990
• DOI: 10.1109/TBCAS.2017.2775638

This paper presents a feasibility study of wireless power and data transmission through an inductive link to a 1-mm 2 implant, to be used as a free-floating neural probe, distributed across a brain area of interest. The proposed structure utilizes a four-coil inductive link for back telemetry, shared with a three-coil link for wireless power transmission. We propose a design procedure for geometrical optimization of the inductive link in terms of power transmission efficiency (PTE) considering specific absorption rate and data rate. We have designed a low-power pulse-based active data transmission circuit and characterized performance of the proposed inductive link in terms of its data rate and bit error rate (BER). The 1-mm 2 data-Tx/power-Rx coil is implemented using insulated bonding wire with 25-μm diameter, resulting in measured PTE in tissue media of 2.01% at 131 MHz and 1.8-cm coil separation distance when the resonator coil inner radius is 1 cm. The measured BER at 1-Mbps data rate was 2.7 × 10 -6 and 5 × 10 -6 in the air and tissue environments, respectively.