An Energy-Efficient Optically-Enhanced Highly-Linear Implantable Wirelessly-Powered Bidirectional Optogenetic...

Area of Science:

• Neuroscience
• Biomedical Engineering
• Optogenetics

Background:

• Optogenetic neurostimulation requires efficient, miniaturized devices for precise neural control.
• Existing systems often face limitations in energy efficiency, size, and integration of recording capabilities.

Purpose of the Study:

• To develop a compact, energy-efficient, bidirectional optogenetic neuro-stimulator.
• To enhance light delivery and control for targeted neural stimulation.
• To integrate neural recording functionalities within the same device.

Main Methods:

• Designed a highly-linear, current-mode micro-LED driver circuit for precise stimulation control.
• Utilized inkjet-printed, custom-designed optical micro-lenses to improve light directivity.
• Integrated Local Field Potential (LFP) recording channels and power management blocks onto a System-on-Chip (SoC).
• Embedded a micro-coil for inductive wireless power transfer.

Main Results:

• Achieved linear control of optical stimulation up to 10 mA with minimal headroom, boosting energy conversion efficiency.
• Demonstrated a 30.46x improvement in power delivery efficiency to target tissue using printed micro-lenses.
• Reported a 2.24% Power Transfer Efficiency (PTE) for the wireless power link.
• Fabricated a self-contained system (6 mm³, 12.5 mg) with integrated μLEDs, μlenses, and recording channels.

Conclusions:

• The developed mm-scale neuro-stimulator offers significant advancements in energy efficiency and miniaturization for optogenetic applications.
• The combination of a novel LED driver and printed optics enhances stimulation performance.
• Integrated bidirectional capabilities (stimulation and recording) in a compact form factor open new possibilities for neuroscience research.