Glassy Carbon Microneedle Interface for Conductive Tissue Penetration

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Solution Overview

Problem

Existing bioelectronic interfaces based on microneedle arrays face challenges due to the limitations of materials used for manufacturing, including insufficient electrical conductivity and mechanical strength, as well as complex fabrication processes, which affect their reliability and functionality.

Innovation Solution

A device comprising a flexible and/or elastic substrate with glassy carbon microneedles operatively coupled with fluidic channels and electrically conductive tracks or pads, allowing for a multimodal, bidirectional interaction with bodily tissues, including electrical, fluidic, or combined electrical and fluidic modes, and capable of penetrating stiff biological tissues effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If silicon or ceramics are used for microneedles, then mechanical strength and penetration capability are improved, but electrical conductivity is insufficient

Engineering Contradiction:
Improvemechanical strengthVSAvoidelectrical conductivity
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention uses glassy carbon as a composite material that combines the mechanical strength of ceramics with the electrical conductivity of conductive materials. Glassy carbon microneedles achieve both hard penetration capability and sufficient electrical conductivity for reliable bioelectronic interfacing, eliminating the trade-off between mechanical strength and electrical conductivity.

Inventive Principle:
Principle #40Composite materials

2Reliability

If metals such as platinum or gold are used for microneedles, then electrical conductivity is improved, but mechanical strength and penetration capability deteriorate due to ductility

Engineering Contradiction:
Improveelectrical conductivityVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

Glassy carbon serves as a composite material that replaces ductile metals while maintaining electrical conductivity. The amorphous carbon structure of glassy carbon provides both the necessary electrical conductivity for bioelectronic applications and the mechanical hardness required for effective skin penetration, eliminating the ductility problem of metallic materials.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If polymer microneedles are used, then ease of fabrication and scalability are improved, but mechanical strength and electrical conductivity are insufficient

Engineering Contradiction:
Improvefabrication scalabilityVSAvoidmechanical strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The invention changes the material parameters by using glassy carbon, which can be fabricated using photolithography techniques similar to polymers but with superior mechanical and electrical properties. The glassy carbon microneedles maintain fabrication scalability while achieving the necessary mechanical strength for penetration and electrical conductivity for reliable interfacing.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If conductive coatings are applied on hard structures, then electrical conductivity is improved, but device complexity and fabrication complexity increase

Engineering Contradiction:
Improveelectrical conductivityVSAvoidfabrication complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention uses homogeneous glassy carbon material throughout the microneedle structure, eliminating the need for separate conductive coatings. This single-material approach simplifies the fabrication process by removing the additional coating step while maintaining both mechanical strength and electrical conductivity throughout the entire microneedle.

Inventive Principle:
Principle #33Homogeneity

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 provides a reliable, scalable, and robust interface with optimal mechanical strength and electrical conductivity, enabling effective skin penetration and bidirectional interaction, supporting various modes of interaction without causing tissue alteration.

Implementation Method 1

a first microneedle (200) comprising a body (201) made of glassy carbon... capable of penetrating stiff biological tissues effectively

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

glassy carbon... optimal electrical conductivity for establishing an electrical connection with the tissues

Methodology Applied
Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentEP4706539A1Device for interfacing a bodily tissue, comprising at least one glassy carbon microneedle and method for producing the device
Publication Date: 2026.03.11 ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (EPFL)
  • EP4706539A1 patent drawingFigure 1A~1B
  • EP4706539A1 patent drawingFigure 2
  • EP4706539A1 patent drawingFigure 3

AI summary

It is disclosed a device (1) for interfacing a bodily tissue comprising: a flexible and/or elastic substrate (100), including at least a first surface (101) and a second surface (102), and at least one microneedle (200), including a body protruding from at least one of said first surface (101) and second surface (102) of the flexible and/or elastic substrate (100). The device (1) is characterized in that the body of the at least one microneedle (200) is made of glassy carbon and is operatively coupled with at least one fluidic channel (300) and/or with at least one electrically conductive track or pad (400), running in or on the flexible and/or elastic substrate (100).