Binder-free stretchable interconnect via biphasic nano-dispersed interface
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Solution Overview
Problem
Traditional stretchable hybrid electronics face limitations due to weak bonding and low stretchability at interfaces between disparate components, such as soft, rigid, and encapsulation modules, primarily due to differences in materials and processing techniques, leading to mechanical mismatch and interfacial failure under deformation.
Innovation Solution
A universal biphasic nano-dispersed (BIND) interface is introduced, comprising interpenetrating phases of metallic nanoparticles and soft elastomeric polymer, allowing modules to be connected without conductive pastes, providing strong adhesion and continuous electrical pathways, even under significant mechanical deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional conductive pastes (ACF, silver paste) are used to connect modules, then electrical connection is achieved, but mechanical mismatch and weak bonding occur leading to interfacial failure under deformation
Solution Approach 1:
The patent changes the physical and chemical parameters of the interfacial material by using a polymer matrix with embedded conductive particles instead of traditional conductive pastes. This parameter change enables the interface to simultaneously achieve strong bonding and high stretchability, resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The patent employs composite materials consisting of a polymer matrix combined with conductive particles (such as metal nanoparticles or conductive fillers). This composite structure provides both the mechanical flexibility needed for stretchability and the electrical conductivity required for reliable connections, thereby resolving the contradiction between interfacial bonding strength and mechanical stretchability.
2Adaptability or versatility
If all-soft electronics are used to eliminate rigid components, then mechanical matching with tissue/skin is improved, but performance gap with Si-based electronics remains
Solution Approach 1:
The patent applies local quality by creating distinct regions within the device: soft regions for mechanical matching with tissue/skin and rigid Si-based regions for high-performance electronics. The stretchable interface selectively connects these different quality regions, allowing each to fulfill its specific function while working together as an integrated system.
Solution Approach 2:
The patent segments the electronic device into functionally distinct modules: soft electronic components for mechanical compliance and rigid Si-based components for computational performance. The stretchable interface acts as a connector between these segmented modules, enabling the system to achieve both mechanical matching and high electronic performance simultaneously.
3Strength
If liquid metal is used to avoid rigid paste, then mechanical adhesion is improved, but surface tension causes smearing and leakage when in direct contact with skin
Solution Approach 1:
The patent introduces a polymer matrix as an intermediary material that embeds conductive particles. This intermediary structure provides the mechanical adhesion benefits of liquid metal while preventing its harmful effects of smearing and leakage. The polymer matrix acts as a containment structure that maintains the conductive pathway without the uncontrolled flow characteristics of liquid metal.
4Strength
If conductive self-healing composite is used as paste substitute, then bonding capability is achieved through voluminous bulk phase, but mechanical mismatch occurs and ultrathin thickness cannot be achieved
Solution Approach 1:
The patent changes the dimensional parameters of the conductive interface by transitioning from bulk-phase conductive composites to a thin-film structure with embedded particles. This parameter change enables the interface to achieve strong bonding capability while maintaining ultrathin thickness, resolving the contradiction between bonding strength and thickness.
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 BIND interface achieves high mechanical and electrical stretchability, with soft-soft modules exhibiting 600% and 180% stretchability respectively, and soft-rigid modules showing 200% electrical stretchability, while maintaining robust interfacial toughness, enhancing the performance and reliability of stretchable devices.
Implementation Method 1
the interface may include interpenetrating phases of metallic nanoparticles and soft elastomeric polymer
Implementation Method 2
exposed and immersed Au nanoparticles maintain a continuous electrical pathway
Implementation Method 3
The BIND interface can be prepared, for example, by thermally evaporating gold (Au) or silver (Ag) nanoparticles onto a ̃100 μm thick self-adhesive styrene-ethylene-butylene-styrene (SEBS) thermoplastic elastomer
Implementation Method 4
Soft-soft modules joined by this interface achieved 600% and 180% mechanical and electrical stretchability, respectively
Implementation Method 5
Encapsulation on soft modules is strongly adhesive, displaying interfacial toughness up to 0.24 N/mm
Data Source
AI summary
Herein disclosed include a flexible electronic device comprising a first component comprising a first biphasic portion, a second component, wherein the first component and the second component are in contact with an electrically conductive stretchable interface configured between the first component and the second component, wherein the electrically conductive stretchable interface comprises the first biphasic portion which is adhered to a portion of the second component, and wherein the first biphasic portion comprises a first polymer having (i) a surface partially covered with metal nanoparticles which are partially exposed at the surface, and (ii) metal nanoparticles which are completely embedded in the first polymer. The disclosure also includes a method of forming the flexible electronic device.