PDMS Stretchable Electrode Array for Spinal Cord Recording
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Solution Overview
Problem
Conventional neuroprosthetic devices are too stiff to be used with moving tissues like the spinal cord, leading to tissue damage and ineffective stimulation or recording due to limited flexibility, stability, and specificity.
Innovation Solution
A device with a flexible and stretchable polymer substrate, embedded with conductive PDMS electrodes and leads, allowing for subdural or epidural implantation, providing improved fixation, specificity, and the ability to deliver pharmaceutical agents, while maintaining conductivity under mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If metallic electrodes are microfabricated onto a biocompatible substrate of polyimide or parylene, then good flexibility and conformability to the environment is achieved, but the device remains too stiff to be used in contact with moving tissues like muscles or the spinal cord
Solution Approach 1:
The patent employs a thin film structure with a total thickness of less than 1 mm, preferably less than 300 micrometers and most preferably less than 50 micrometers. This ultra-thin design allows the device to conform to moving tissues like the spinal cord while maintaining structural integrity for electrical stimulation and signal recording functions.
2Object-affected harmful factors
If the device is made more flexible to conform to moving tissues, then tissue damage and implant destruction are reduced, but the ability to deliver sufficient electrical charges may be compromised
Solution Approach 1:
The patent uses composite material structures combining biocompatible substrates (polyimide or parylene) with metallic electrodes. This composite approach allows the device to achieve both mechanical flexibility for tissue compatibility and sufficient electrical conductivity for delivering therapeutic charges without causing tissue damage.
Solution Approach 2:
The patent optimizes the thickness parameter of the device to less than 1 mm (preferably less than 300 micrometers, most preferably less than 50 micrometers). This parameter change enables the device to be flexible enough to conform to moving tissues while maintaining the electrical properties necessary for effective charge delivery.
3Shape
If the device thickness is reduced to improve flexibility, then conformability to spinal cord is improved, but manufacturing precision and electrode integrity become more challenging
Solution Approach 1:
The patent employs advanced thin film fabrication techniques to create a device with total thickness of less than 1 mm (preferably less than 300 micrometers, most preferably less than 50 micrometers). These thin film processes enable precise electrode patterning and integration while maintaining the flexibility needed to conform to the spinal cord surface.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device enables stable, specific electrical and pharmaceutical stimulation, and recording of neural signals with reduced tissue damage, improved fixation, and enhanced locomotion in paralyzed subjects.
Implementation Method 1
a conformable substrate which is primarily composed of (essentially consists of) a flexible and stretchable polymer; and a plurality of flexible electrodes and/or conductive leads embedded in the conformable substrate. The electrodes and/or leads are stretchable.
Data Source
AI summary
An implantable device for the electrical and/or pharmaceutical stimulation of the central nervous system, especially the spinal cord, is suggested. The device comprises a conformable substrate which is primarily composed of a flexible and stretchable polymer, and a plurality of flexible electrodes and conductive leads embedded in the conformable substrate. Not only the substrate, but also the leads are stretchable. The substrate may consist of PDMS, and the leads may consist of a conductive PDMS, in particular, PDMS with an electrically conductive filler material, and may optionally be metal-coated. The device defines a multi-electrode array which may be employed for neurostimulation in the epidural or subdural space of an animal or human.