Thiol-Ene Shape Memory Polymer for Hydrolytically Stable Bioelectronics

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Solution Overview

Problem

Current shape memory polymers (SMPs) used in bio-electronic devices are prone to hydrolytic decomposition due to ester groups in their backbone, limiting the duration of chronic in vivo implantation.

Innovation Solution

Development of thiol-ene SMPs with ester-free backbones, synthesized through a method involving a mixture of monomers with thiol and alkene functional groups, which form a backbone via thiol-ene linkages, enhancing hydrolytic stability and mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If shape memory polymers with ester groups in backbone are used, then the device can undergo thermal induced softening to reduce modulus mismatch, but the polymer is prone to hydrolytic decomposition limiting chronic implantation duration

Engineering Contradiction:

Improvethermal induced softening capabilityVSAvoidchronic implantation duration

Core Design Contradiction:

Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent removes ester groups from the polymer backbone through alternative polymerization chemistry (thiol-ene click chemistry), extracting the harmful hydrolyzable component while retaining the shape memory functionality through carefully selected monomer structures

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the chemical composition parameters of the polymer backbone by selecting monomers with hydrolytically stable bonds (thiol-ene linkages instead of ester bonds), fundamentally altering the chemical stability parameter while maintaining the thermal response properties

Inventive Principle:

Principle #35Parameter changes

2Reliability

If shape memory polymers are used to reduce modulus mismatch, then device failure is mitigated, but mechanical stability for extended periods remains compromised due to hydrolysis

Engineering Contradiction:

Improvedevice failure mitigationVSAvoidmechanical stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent employs composite monomer systems combining thiol-functionalized shape memory units with hydrolytically stable alkene units, creating a composite polymer structure that integrates both shape memory functionality and enhanced hydrolytic stability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent converts the typically harmful effect of water exposure (hydrolysis) into a beneficial opportunity by designing a polymer that specifically resists hydrolysis, turning the aqueous physiological environment from a degrading factor into a neutral or even beneficial testing condition for the improved stability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Stability of the object's composition

If ester-free thiol-ene polymers are synthesized, then hydrolytic stability is improved, but the synthesis complexity increases with photo-initiation requirements

Engineering Contradiction:

Improvehydrolytic stabilityVSAvoidsynthesis complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces traditional thermal or chemical initiation methods with photo-initiation, substituting a photochemical system that offers better control, lower temperatures, and reduced side reactions, thereby managing synthesis complexity through superior process control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Duration of action of stationary object

If chronic implantation is extended, then more time for neural recording/stimulation is achieved, but neuroinflammatory responses and tissue damage increase

Engineering Contradiction:

Improveimplantation durationVSAvoidneuroinflammatory responses

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of prolonged presence in the body (which normally causes inflammation) into a benefit by ensuring the polymer remains stable and inert over that prolonged period, preventing the very degradation products that would trigger inflammatory responses

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 thiol-ene SMPs demonstrate improved resistance to hydrolytic degradation, maintaining mechanical stability and biocompatibility, potentially remaining stable for several months to years in vivo, and facilitating reduced tissue inflammation through controlled release of anti-inflammatory agents.

Implementation Method 1

adding a photo-initiate-able catalytic agent to the monomer mixture to form a reaction mixture and photo-initiating the photo-initiate-able catalytic agent to form a free radical catalyst to thereby initiate step-growth polymerization

Methodology Applied

Scientific EffectPhoto-initiation: Photopolymerisation

Data Source

PatentUS11584867B2Bio-electronic devices including hydrolytically stable polymers

Publication Date: 2023.02.21 BOARD OF RGT THE UNIV OF TEXAS SYST

AI summary

Bio-electronic devices including a substrate layer composed of a thiol-ene shape memory polymer, the polymer including, a sequential chain of a first type of monomer covalently bonded to a second type of monomer via thiol-ene linkages that form a backbone of the polymer, and. at least one patterned gold interconnect line adhered to the substrate layer.