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

Seunghyeon Yun; Chin Su Koh; Jungmin Seo; Shinyong Shim; Minkyung Park; Hyun Ho Jung; Kyungsik Eom; Jin Woo Chang; Sung June Kim

doi:10.3390/s22020501

Sensors (Jan 2022)

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

Seunghyeon Yun,
Chin Su Koh,
Jungmin Seo,
Shinyong Shim,
Minkyung Park,
Hyun Ho Jung,
Kyungsik Eom,
Jin Woo Chang,
Sung June Kim

Affiliations

Seunghyeon Yun: Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea
Chin Su Koh: Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea
Jungmin Seo: Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea
Shinyong Shim: Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea
Minkyung Park: Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea
Hyun Ho Jung: Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea
Kyungsik Eom: Department of Electronics Engineering, College of Engineering, Pusan National University, Busan 46241, Korea
Jin Woo Chang: Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea
Sung June Kim: Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea

DOI: https://doi.org/10.3390/s22020501
Journal volume & issue: Vol. 22, no. 2
p. 501

Abstract

Read online

Spinal cord stimulation is a therapy to treat the severe neuropathic pain by suppressing the pain signal via electrical stimulation of the spinal cord. The conventional metal packaged and battery-operated implantable pulse generator (IPG) produces electrical pulses to stimulate the spinal cord. Despite its stable operation after implantation, the implantation site is limited due to its bulky size and heavy weight. Wireless communications including wireless power charging is also restricted, which is mainly attributed to the electromagnetic shielding of the metal package. To overcome these limitations, here, we developed a fully implantable miniaturized spinal cord stimulator based on a biocompatible liquid crystal polymer (LCP). The fabrication of electrode arrays in the LCP substrate and monolithically encapsulating the circuitries using LCP packaging reduces the weight (0.4 g) and the size (the width, length, and thickness are 25.3, 9.3, and 1.9 mm, respectively). An inductive link was utilized to wirelessly transfer the power and the data to implanted circuitries to generate the stimulus pulse. Prior to implantation of the device, operation of the pulse generator was evaluated, and characteristics of stimulation electrode such as an electrochemical impedance spectroscopy (EIS) were measured. The LCP-based spinal cord stimulator was implanted into the spared nerve injury rat model. The degree of pain suppression upon spinal cord stimulation was assessed via the Von Frey test where the mechanical stimulation threshold was evaluated by monitoring the paw withdrawal responses. With no spinal cord stimulation, the mechanical stimulation threshold was observed as 1.47 ± 0.623 g, whereas the stimulation threshold was increased to 12.7 ± 4.00 g after spinal cord stimulation, confirming the efficacy of pain suppression via electrical stimulation of the spinal cord. This LCP-based spinal cord stimulator opens new avenues for the development of a miniaturized but still effective spinal cord stimulator.

Published in Sensors

ISSN: 1424-8220 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Chemical technology
Website: http://www.mdpi.com/journal/sensors

About the journal

Abstract

Keywords