Stretchable Bioelectronic Fibers Using Liquid Metal Conductors
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Solution Overview
Problem
Current approaches to developing soft medical interfaces for bioelectronic medicine face challenges in achieving strain-insensitivity, low-modulus elasticity, and high electrical conductivity, often requiring resource-intensive cleanroom processes and resulting in poor scalability and mechanical fragility.
Innovation Solution
The development of soft and stretchable bioelectronic interfaces using elastic microelectronic fibers with liquid metal-filled channels and microelectronic components, integrated into a low-modulus elastomeric substrate, allowing for scalable fabrication and robust mechanical performance while maintaining electrical functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If geometric patterns are used to enable stretchability in high-modulus solid conductors, then stretchability is achieved, but device complexity and fabrication difficulty increase due to required cleanroom processes and transfer printing steps
Solution Approach 1:
The patent changes the physical state of the conductor from solid to liquid, eliminating the need for geometric patterning. Liquid metal conductors naturally accommodate strain through fluid flow, providing stretchability without complex microfabrication patterns or cleanroom processes.
Solution Approach 2:
The patent replaces the mechanical geometric pattern system with a fluid-based electrical conduction system. Instead of relying on engineered microstructures to provide stretchability, the liquid metal's fluid properties inherently provide strain insensitivity and stretchability.
2Adaptability or versatility
If thin micro-cracked metal films are used to achieve multiaxial stretchability, then stretchability up to 5-8% is achieved, but electrical conductivity deteriorates
Solution Approach 1:
The patent changes the conductor from solid metal film to liquid metal, eliminating crack formation. The liquid metal flows to maintain continuous electrical pathways during deformation, providing both high stretchability and maintained conductivity without the trade-off present in solid cracked films.
3Adaptability or versatility
If complex microfabrication approaches are used, then stretchable structures are achieved, but scalability and manufacturing efficiency worsen due to poor size and number scalability
Solution Approach 1:
The patent extracts the conductor material from the solid state and uses it in liquid form, eliminating the need for complex microfabrication processes. This enables direct fabrication methods that scale much better with device size and quantity, removing the bottleneck of sequential transfer printing steps.
4Strength
If high-modulus solid conductors are used, then structural strength is achieved, but elasticity and stretchability worsen
Solution Approach 1:
The patent changes the mechanical state of the conductor from solid to liquid. The liquid metal is contained within a flexible encapsulation structure, providing both the structural strength needed for device integrity and the elasticity/stretchability required for conformal attachment to moving organs.
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
These interfaces enable chronic implantation on diverse organ surfaces, providing scalable, high-conductivity, and strain-insensitive bioelectronic solutions for sensing and stimulation, addressing the limitations of previous technologies by ensuring reliable mechanical and electrical performance.
Implementation Method 1
liquid metal can be non-toxic and can have a melting point of less than 37° C. The microelectronic component can stimulate and/or sense the organ physiology in response to an electrical signal and/or electrical power carried by the liquid metal
Implementation Method 2
elastic microelectronic fibers, also called elastomeric fibers, produced through thermal drawing
Implementation Method 3
by ablating a hole in the elastomeric fiber with a femtosecond/picosecond pulsed laser to expose a portion of the liquid metal
Data Source
AI summary
A soft, stretchable, multifunctional bioelectronic interface can be used to monitor and/or modulate an entire organ, such as a stomach, heart, bladder, or spinal cord. The interface's softness translates to reduced mechanical mismatch with the tissue, and the interface's stretchability reduces interfacial stress with dynamically expanding and contracting organs. The electronics are stretchable thanks in part to liquid-metal conductors sealed within hollow channels of elastomeric fibers embedded in the interface. The liquid metal is largely strain-insensitive, non-toxic, and has a melting point of less than 37° C., so it remains liquid when implanted in a mammalian body. The liquid metal conductors connect microelectronic components, such as micro light-emitting diodes (μLEDs), electrodes, photodiodes, and temperature sensors, to a flexible printed circuit board (fPCB) at one end of the fiber. The interface may include other microelectronic components, such as piezoelectric strain sensors, that are also coupled to the fPCB.