Programmable high-output-impedance, large-voltage compliance, microstimulator for low-voltage biomedical applications

Area of Science:

• Biomedical Engineering
• Microelectronics
• Implantable Devices

Background:

• Low-voltage biomedical applications require precise and efficient stimulation.
• Existing microstimulators often face limitations in output impedance and voltage compliance.
• The development of compact, high-performance stimulation circuits is crucial for advancing neuromodulation and other implantable technologies.

Purpose of the Study:

• To design and simulate a programmable microstimulator with high output impedance and large voltage compliance.
• To enable precise biphasic current pulse generation for low-voltage biomedical applications.
• To achieve a compact circuit design suitable for microelectrode integration.

Main Methods:

• A 6-bit binary-weighted digital-to-analog converter (DAC) was employed for generating biphasic stimulus current pulses.
• A compact current mirror circuit was utilized to achieve high output voltage compliance and resistance.
• The microstimulator was designed and simulated using a standard 0.18µm CMOS process.

Main Results:

• The microstimulator circuit successfully delivered a maximum stimulation current of 160µA into a 10-kΩ load.
• Operating at a 1.8-V supply, the output stage demonstrated a voltage compliance of 1.69V and an output resistance of 160MΩ.
• The core microelectrode circuit achieved a compact layout size of 25.5µm×31.5µm.

Conclusions:

• The designed microstimulator meets the requirements for low-voltage biomedical stimulation with its high output impedance and voltage compliance.
• The circuit's performance, including current delivery, voltage compliance, and output resistance, is suitable for various biomedical applications.
• The compact design and efficient operation make this microstimulator a promising component for future implantable devices.