A Modular 32-site wireless neural stimulation microsystem

Ghovanloo, Maysam; Najafi, K.

doi:10.1109/jssc.2004.837026

Cited by 134 publications

(47 citation statements)

References 26 publications

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“…6,7,10,12,[17][18][19][20]23,27,33,35,39 In addition, studies have been conducted on the effects of implantable chips placed on the retina, cardiac muscle, and other structures within the body. 4,8,15,16,26,30,34,37 However, much less has been done on the consequences of wirelessly powering devices within the skull 14,31 . In this work, a 2-D numerical model with approximations to 3D was developed and implemented to provide an analysis of the SAR values and temperature changes in the cortical tissue surrounding the implanted and electromagnetically-excited BMI chip(s).…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Power Absorption and Temperature Changes due to Brain Machine Interface Operation

2007

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To fully understand neural function, chronic neural recordings must be made simultaneously from 10s or 100s of neurons. To accomplish this goal, several groups are developing brain machine interfaces. For these devices to be viable for chronic human use, it is likely that they will need to be operated and powered externally via a radiofrequency (RF) source. However, RF exposure can result in tissue heating and is regulated by the FDA/FCC. This paper provides an initial estimate of the amount of tissue heating and specific absorption rate (SAR) associated with the operation of a brain-machine interface (BMI). The operation of a brain machine interface was evaluated in an 18-tissue anatomically detailed human head mesh using simulations of electromagnetics and bio-heat phenomena. The simulations were conducted with a single chip, as well as with eight chips, placed on the surface of the human brain and each powered at four frequencies (13.6 MHz, 1.0 GHz, 2.4 GHz, and 5.8 GHz). The simulated chips consist of a wire antenna on a silicon chip covered by a Teflon dura patch. SAR values were calculated using the finite-difference time-domain method and used to predict peak temperature changes caused by electromagnetic absorption in the head using two-dimensional bio-heat equation. Results due to SAR alone show increased heating at higher frequencies, with a peak temperature change at 5.8 GHz of approximately 0.018 degrees C in the single-chip configuration and 0.06 degrees C in the eight-chip configuration with 10 mW of power absorption (in the human head) per chip. In addition, temperature elevations due to power dissipation in the chip(s) were studied. Results show that for the neural tissue, maximum temperature rises of 3.34 degrees C in the single-chip configuration and 7.72 degrees C in the eight-chip configuration were observed for 10 mW dissipation in each chip. Finally, the maximum power dissipation allowable in each chip before a 1.0 degrees C temperature increase (most stringent standards as denoted in the FDA guidelines) is exceeded in the head was simulated and found to be 2.92 mW in the single-chip configuration and 1.25 mW in the eight-chip configuration. As thermal heating due to SAR was insignificant, this study suggests that wireless electromagnetics, i.e., RF may be a viable option for powering, and communicating with brain machine interfaces for clinical applications.

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Section: Introductionmentioning

confidence: 99%

Electromagnetic Power Absorption and Temperature Changes due to Brain Machine Interface Operation

2007

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“…Moreover, a cortical recording implant was fabricated on a 2.2 mm 9 2.2 mm chip in 1.5 lm standard n-well CMOS process by Yoon-Kyu et al [39]. Ghovanloo and Najafi, [66] reported another wireless microstimulating chip for neural prosthesis applications with dimension of 4.6 mm 9 4.6 mm fabricated in 1.5 lm CMOS technology. Currently research is being carried out to develop a power efficient communication algorithm in order to both preserve the battery power in case of battery operated implants and reduce the health risks associated with energy transmission.…”

Section: Power Sourcementioning

confidence: 99%

Closed loop deep brain stimulation: an evolving technology

Hosain

Kouzani

Tye

2014

Australas Phys Eng Sci Med

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Deep brain stimulation is an effective and safe medical treatment for a variety of neurological and psychiatric disorders including Parkinson's disease, essential tremor, dystonia, and treatment resistant obsessive compulsive disorder. A closed loop deep brain stimulation (CLDBS) system automatically adjusts stimulation parameters by the brain response in real time. The CLDBS continues to evolve due to the advancement in the brain stimulation technologies. This paper provides a study on the existing systems developed for CLDBS. It highlights the issues associated with CLDBS systems including feedback signal recording and processing, stimulation parameters setting, control algorithm, wireless telemetry, size, and power consumption. The benefits and limitations of the existing CLDBS systems are also presented. Whilst robust clinical proof of the benefits of the technology remains to be achieved, it has the potential to offer several advantages over open loop DBS. The CLDBS can improve efficiency and efficacy of therapy, eliminate lengthy start-up period for programming and adjustment, provide a personalized treatment, and make parameters setting automatic and adaptive.

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“…In BFSK modulation the binary data are represented by constant amplitude using two different frequencies, where logic 1 is assigned to one frequency and logic 0 is assigned to the other. Compared to BASK, BFSK can provide data-to-carrier frequency ratio as high as 67% (Ghovanloo and Najafi, 2003, 2004b. However, the BFSK scheme requires a wide pass band in the inductive link to allow different frequencies, which limits the power transfer due to high filtration by RLC components.…”

Section: Downlinkmentioning

confidence: 99%

Design Considerations of Biomedical Telemetry Devices

Nikita

2014

Handbook of Biomedical Telemetry

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A Modular 32-site wireless neural stimulation microsystem

Cited by 134 publications

References 26 publications

Electromagnetic Power Absorption and Temperature Changes due to Brain Machine Interface Operation

Electromagnetic Power Absorption and Temperature Changes due to Brain Machine Interface Operation

Closed loop deep brain stimulation: an evolving technology

Design Considerations of Biomedical Telemetry Devices

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