Advanced Neural Probes

On-Probe Neural Interface ASIC for Combined

Electrical Recording and Optogenetic Stimulation

Our interest in this work is to develop an electronic control system, which can both drive high radiance µLEDs and perform electronic recording. We propose an architecture designed for long term chronic use when integrated onto implantable probes. We have thus designed stimulator drivers to utilize high efficiency (∼30%) LEDs, which can achieve total system efficiencies in excess of 20%. This is important for both minimizing undesirable surface heating and ensuring low-power battery operation. Our design records local field potentials as these have proven to be most stable for long term chronic studies.

Figure 1: Proposed optrode conceptwith passive silicon probe bonded to an active CMOS neural interface ASIC.

CMOS chip.png

Figure 2: System architecture for the proposed neural interface ASIC. This supports 4 neural recording channels and 6 optical stimulation sites.

  • This paper presents a neural interface ASIC for intelligent optogenetic-optoelectronic probes.

  • The architecture is designed to enable simultaneous optical neural stimulation and electronic recording.

  • It provides four low noise (1.15 Vrms) recording channels optimized for recording local field potentials (0.02 – 830 Hz bandwidth, _5mV range, sampled 10-bit@4 kHz)

  • For stimulation it provides six independently addressable optical driver circuits, which can provide both intensity (8-bit resolution across a 1.1mA range) and pulse-width modulation for high radiance LEDs.

neural data.png

Figure 3: In-vitro neurological recordings (LFP recording) from transgenic mouse (genetically modified to have light-sensitive cells) brain slice while optical stimulation is applied. Observed data contains cell depolarization and neural cell responses. According to this experiment, neural activity up to 3 mV and 33 Hz are recorded in response to 0.8 mW illumination power.

Relevant Publications:

  1. Ramezani R, Liu Y, Dekhoda F, Soltan A, Haci D, Zhao H, Firfilionis D, Hazra A, Cunningham M, Jackson A, Constandinou T, Degenaar P. On-Probe Neural Interface ASIC for Combined Electrical Recording and Optogenetic Stimulation. IEEE Transactions on Biomedical Circuits and Systems 2018, 12(3), 576-588.

  2. Ramezani R, Dehkhoda F, Soltan A, Degenaar P, Liu Y, Constandinou T. An Optrode with Built-in Self-Diagnostic and Fracture Sensor for Cortical Brain Stimulation.In: 2016 IEEE Biomedical Circuits and Systems Conference (BioCAS). 2017, Shanghai: IEEE.

  3. Dehkhoda F, Soltan A, Ramezani R, Degenaar P. Biphasic Micro-LED Driver for Optogenetics. In: 2016 IEEE Biomedical Circuits and Systems Conference (BioCAS). 2016, Shanghai: IEEE.

  4. Zhao H, Dehkhoda F, Ramezani R, Sokolov D, Degenaar P. A CMOS-based Neural Implantable Optrode for Optogenetic Stimulation and Electrical Recording. In: 2015 IEEE Biomedical Circuits and Systems Conference (BioCAS). 2015, Atlanta, Georgia, USA: IEEE.

  5. Dehkhoda F, Soltan A, Ramezani R, Zhao H, Liu Y, Constandinou T, Degenaar P. Smart Optrode for Neural Stimulation and Sensing. In: 2015 IEEE Sensors. 2015, Busan, South Korea: IEEE.