Stimulus driver for epilepsy seizure suppression with adaptive loading impedance

Area of Science:

• Biomedical Engineering
• Neuroscience
• Electrical Engineering

Background:

• Epileptic seizures pose significant challenges for control and management.
• Implantable micro-stimulators offer a promising avenue for therapeutic interventions.
• Precise and reliable stimulus delivery is critical for effective neuromodulation.

Purpose of the Study:

• To design and validate a stimulus driver circuit for an implantable micro-stimulator.
• To achieve a consistent output of 30 µA stimulus current across a wide range of electrode impedances (20–200 kΩ).
• To integrate the driver circuit into a closed-loop system for epileptic seizure monitoring and control.

Main Methods:

• Development of a stimulus driver circuit comprising an output stage, control block, and adaptor.
• Integration of the driver circuit onto a single complementary metal-oxide-semiconductor (CMOS) chip using a 0.35 µm 3.3 V/24 V process.
• Testing the driver's performance in a closed-loop epileptic seizure monitoring and controlling system.
• Verification of functionality through experimental results in Long-Evans rats exhibiting epileptic seizures.

Main Results:

• The stimulus driver circuit successfully delivered 30 µA stimulus currents within the specified electrode impedance range (20–200 kΩ).
• The averaged power consumption of the driver was measured to be between 0.24–0.56 mW at an 800 Hz stimulation rate.
• The integrated circuit was successfully applied to a closed-loop system and validated in an animal model.

Conclusions:

• The proposed stimulus driver circuit is effective for precise current delivery in implantable micro-stimulators for epilepsy control.
• The single-chip integrated design offers a power-efficient solution for neuromodulation applications.
• Experimental validation in rats confirms the system's potential for managing epileptic seizures.