A Fully Implantable Miniaturized Liquid Crystal Polymer (LCP)-Based Spinal Cord Stimulator for Pain Control

Area of Science:

• Biomedical Engineering
• Neuroscience
• Materials Science

Background:

• Conventional spinal cord stimulators (SCS) use bulky, heavy, metal-packaged implantable pulse generators (IPGs) that limit implantation sites and wireless capabilities.
• The electromagnetic shielding of metal IPGs restricts wireless power charging and data transmission, posing challenges for miniaturization and patient convenience.

Purpose of the Study:

• To develop a fully implantable, miniaturized spinal cord stimulator using a biocompatible liquid crystal polymer (LCP) substrate and packaging.
• To overcome the size, weight, and wireless communication limitations of traditional SCS devices.
• To evaluate the efficacy of the novel LCP-based SCS in suppressing neuropathic pain in an animal model.

Main Methods:

• Fabrication of an LCP-based SCS device with integrated electrode arrays and encapsulated circuitry, achieving significant reductions in size and weight.
• Utilized an inductive link for wireless power and data transfer to the implanted circuitry for pulse generation.
• Assessed device performance through electrochemical impedance spectroscopy (EIS) and implanted the device in a spared nerve injury rat model.
• Evaluated pain suppression efficacy using the Von Frey test to measure the mechanical stimulation threshold before and after SCS.

Main Results:

• The LCP-based SCS device achieved a weight of 0.4 g and dimensions of 25.3 x 9.3 x 1.9 mm.
• Wireless power and data transfer were successfully implemented via an inductive link.
• In a rat model, spinal cord stimulation significantly increased the mechanical stimulation threshold from 1.47 ± 0.623 g to 12.7 ± 4.00 g, confirming effective pain suppression.
• Electrochemical impedance spectroscopy confirmed the characteristics of the stimulation electrodes.

Conclusions:

• The developed LCP-based spinal cord stimulator represents a significant advancement in miniaturized neuromodulation devices.
• This technology overcomes the limitations of conventional SCS, offering a smaller, lighter, and wirelessly powered solution for severe neuropathic pain.
• The study demonstrates the potential of LCP as a biocompatible material for advanced implantable medical devices, paving the way for more effective pain management therapies.