Rush A.D.,Illinois Institute of Technology |
Rush A.D.,Plexon Inc. |
Troyk P.R.,Illinois Institute of Technology |
Troyk P.R.,Sigenics Inc.
IEEE Transactions on Biomedical Engineering | Year: 2012
A wireless cortical neural recording system with a miniature-implanted package is needed in a variety of neuroscience and biomedical applications. Toward that end, we have developed a transcutaneous two-way communication and power system for wireless neural recording. Wireless powering and forward data transmission (into the body) at 1.25 Mbps is achieved using a frequency-shift keying modulated class E converter. The reverse telemetry (out of the body) carrier frequency is generated using an integer-N phase-locked loop, providing the necessary wideband data link to support simultaneous reverse telemetry from multiple implanted devices on separate channels. Each channel is designed to support reverse telemetry with a data rate in excess of 3 Mbps, which is sufficient for our goal of streaming 16 channels of raw neural data. We plan to incorporate this implantable power and telemetry system in a 1-cm diameter single-site cortical neural recording implant. © 2012 IEEE. Source
Cogan S.F.,EIC Laboratories, Inc. |
Troyk P.R.,Illinois Institute of Technology |
Demichele G.,Illinois Institute of Technology |
Demichele G.,Sigenics Inc.
International IEEE/EMBS Conference on Neural Engineering, NER | Year: 2013
The stability of thin-film multielectrode devices fabricated on flexible polyimide substrates was evaluated for wireless subdural recording and stimulation in intracranial electrocorticogram (ECoG) monitoring prior to epilepsy surgery. Devices were fabricated with either 48 or 64 sputtered iridium oxide (SIROF) electrodes. Power and bidirectional data transfer were provided via 121 kHz and 13.56 MHz RF links, respectively. A 64-channel application specific integrated circuit (ASIC) was developed for the devices and provided both the recording and stimulation capability. The ASIC, supporting discrete electronic components, and data/power coils were incorporated on a polyimide substrate and protected from the saline environment by a combination of amorphous silicon carbide (a-SiC) and silicone encapsulants. Soak testing at 37°C in saline under continuous power, and unpowered soak testing at 87°C, were conducted for 29 days and 12 days, respectively. Normal function of the ASIC and device, as measured by the consistency in RMS signal strength and stimulation driving voltage, was observed over the test periods. The charge capacity measured by cyclic voltammetry and the impedance of the SIROF electrodes remained stable over 20 days at 87°C. The results suggest that a-SiC and silicone encapsulants can protect active electronics for implantation periods up to 29 days, the maximum length anticipated for ECoG monitoring in epilepsy patients. © 2013 IEEE. Source
Hu Z.,Sigenics Inc.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011
For many emerging neural prosthesis designs that are powered by inductive coupling, their small physical size requires large current in the extracorporeal transmitter coil, and the Class-E power amplifier topology is often used for the transmitter design. Tuning of Class-E circuits for efficient operation is difficult and a self-tuned circuit can facilitate the tuning. The coil current is sensed and used to tune the switching of the transistor switch in the Class-E circuit in order to maintain its high-efficiency operation. Although mathematically complex, the analysis and design procedure for the self-tuned Class-E circuit can be simplified due to the current feedback control, which makes the phase angle between the switching pulse and the coil current predetermined. In this paper explicit analytical design equations are derived and a detailed design procedure is presented and compared with the conventional Class-E design approaches. Source
Merrill D.R.,Alfred E Mann Foundation For Scientific Research |
Lockhart J.,Alfred E Mann Foundation For Scientific Research |
Troyk P.R.,Sigenics Inc. |
Weir R.F.,Rehabilitation Institute of Chicago |
Hankin D.L.,Alfred E Mann Foundation For Scientific Research
Artificial Organs | Year: 2011
Modern hand and wrist prostheses afford a high level of mechanical sophistication, but the ability to control them in an intuitive and repeatable manner lags. Commercially available systems using surface electromyographic (EMG) or myoelectric control can supply at best two degrees of freedom (DOF), most often sequentially controlled. This limitation is partially due to the nature of surface-recorded EMG, for which the signal contains components from multiple muscle sources. We report here on the development of an implantable myoelectric sensor using EMG sensors that can be chronically implanted into an amputee's residual muscles. Because sensing occurs at the source of muscle contraction, a single principal component of EMG is detected by each sensor, corresponding to intent to move a particular effector. This system can potentially provide independent signal sources for control of individual effectors within a limb prosthesis. The use of implanted devices supports inter-day signal repeatability. We report on efforts in preparation for human clinical trials, including animal testing, and a first-in-human proof of principle demonstration where the subject was able to intuitively and simultaneously control two DOF in a hand and wrist prosthesis. © 2011, © the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc. Source
Hu Z.,Sigenics Inc.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2012
Activated Iridium Oxide Film (AIROF) microelectrodes are regarded as advantage for stimulation of neural tissue owing to their superior charge injection capabilities, as compared to other noble-metal based electrodes. Including AIROF electrodes within an implantable neural stimulator can be challenging since the stimulator fabrication steps often involve elevated temperatures at which the AIROF can be damaged. In this work, a wireless neural stimulator application-specific-integrated-circuit (ASIC) was used to intrinsically activate iridium microelectrodes. This intrinsic activation allows for the growth of the AIROF as the final assembly step after the entire device is assembled, thus avoiding stress on the AIROF. Since a typical neural stimulator is essentially a current-controlled driver with voltage compliance limits, its output waveform can be tuned to match the traditional voltage pulsing/ramp activation waveform. Here the feasibility of the current driven activation of iridium electrodes, over a wireless link, is demonstrated. Source