Compact, Energy-Efficient High-Frequency Switched Capacitor Neural Stimulator With Active Charge Balancing

Area of Science:

• Biomedical Engineering
• Neural Engineering
• Implantable Devices

Background:

• Safety and energy efficiency are critical challenges for implantable neural stimulators.
• Variations in electrode impedance can compromise stimulation control and device longevity.
• Existing stimulation methods face limitations in efficiency and adaptability.

Purpose of the Study:

• To present a novel high-frequency, switched capacitor (HFSC) stimulation and active charge balancing scheme.
• To enhance energy efficiency and achieve precise charge control for neural stimulators.
• To enable compact, multichannel stimulation capabilities for implantable devices.

Main Methods:

• Developed a high-frequency, switched capacitor (HFSC) stimulation and active charge balancing circuit.
• Integrated the HFSC stimulator using 0.18 μm high-voltage technology.
• Performed theoretical analysis and experimental validation of the proposed scheme.

Main Results:

• Achieved 50% peak energy efficiency.
• Demonstrated well-controlled stimulation charge despite large electrode impedance variations.
• Confirmed the effectiveness of active charge balancing in preventing electrode dissolution.
• Fabricated a compact single stimulator occupying 0.035 mm².

Conclusions:

• The proposed HFSC stimulation scheme offers significant advantages over traditional constant-current and voltage-mode methods.
• The compact and efficient design facilitates multichannel stimulation for advanced neural interfaces.
• The active charge balancing ensures device safety and longevity, crucial for implantable applications.