ASIC or PIC? Implantable stimulators based on semi-custom CMOS technology or low-power microcontroller architecture

Area of Science:

• Biomedical Engineering
• Neuroscience

Background:

• Chronic muscle stimulation requires complex, varied patterns beyond simple frequencies.
• Existing methods for neuromuscular stimulation lack the necessary pattern complexity.

Purpose of the Study:

• To design and evaluate two novel implantable neuromuscular stimulators capable of generating diverse stimulation patterns.
• To assess the reliability and feasibility of these devices for long-term mammalian muscle studies.

Main Methods:

• Developed two implantable neuromuscular stimulator prototypes: one based on a semi-custom Application Specific Integrated Circuit (ASIC) and another on a commercial microcontroller (Microchip PIC16C84).
• Both devices were tested in long-term experiments with small mammals (rabbits and rats).
• Evaluated device reliability, flexibility, and implantation suitability.

Main Results:

• The ASIC-based device offered high reliability but lacked flexibility for pattern changes.
• The microcontroller-based device provided software-defined flexibility for varied patterns and demonstrated comparable reliability to the ASIC approach.
• Devices were successfully implanted subcutaneously in rabbits and intraperitoneally in rats, operating at low current drain (<40 microA).

Conclusions:

• Microcontroller-based neuromuscular stimulators offer a flexible and reliable solution for complex, chronic muscle stimulation research.
• These devices are suitable for long-term implantation in small mammals, advancing the study of muscle physiology.
• The ability to reprogram patterns post-implantation enhances experimental versatility.