Liquid Metal Microtube Sensor for Wearable Pulse Monitoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional silicon-based devices and conductive materials are mechanically stiff and brittle, limiting the development of flexible, stretchable, and wearable sensors that can effectively monitor mechanical perturbations and conform to 3D curvatures, while existing solutions require complex and expensive manufacturing methods, restricting scalability and reproducibility.
Innovation Solution
A flexible, stretchable, and ultrathin wearable tactile sensor with a liquid-state conductive element core within a soft silicone elastomer microtube, allowing for high sensitivity and conformability, with a tiny footprint and ultrathin wall thickness, enabling robust and responsive force measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional silicon-based devices and conductive materials are used, then manufacturing precision and structural stability are improved, but mechanical flexibility and stretchability deteriorate
Solution Approach 1:
The patent changes the material parameters by using liquid metal (gallium-based alloy) instead of conventional solid conductive materials, and employs a two-layer silicone elastomer structure with different Shore durometer values (10 and 20) to achieve both flexibility and structural stability. The liquid metal's ability to flow and adapt to deformation while maintaining electrical conductivity resolves the contradiction between mechanical flexibility and electrical stability.
Solution Approach 2:
The invention creates a composite structure combining liquid metal core with silicone elastomer coating, and further integrates this into a two-layer elastomer system. This composite approach allows the liquid metal to provide electrical conductivity while the silicone elastomer provides mechanical flexibility and protection, resolving the contradiction between material properties.
2Reliability
If complex manufacturing methods such as transfer printing, electroless deposition, or screen printing are used, then sensor functionality is improved, but device complexity and production cost increase
Solution Approach 1:
The patent extracts the complex manufacturing processes (transfer printing, electroless deposition, screen printing) and replaces them with a simplified liquid injection method. The liquid metal is directly injected into the elastomer tube through a catheter, eliminating the need for complex deposition and transfer processes while maintaining sensor functionality.
Solution Approach 2:
The invention uses hydraulic principles by injecting liquid metal through a catheter into the elastomer tube. This fluid-based injection method simplifies the manufacturing process compared to solid material deposition techniques, reducing device complexity while ensuring reliable sensor functionality.
3Adaptability or versatility
If conventional conductive materials are deposited onto stretchable substrates, then mechanical deformability is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of depositing conductive materials onto a substrate (conventional approach), the patent inverts the process by enclosing liquid conductive material within a flexible elastomer tube. This inversion simplifies manufacturing because the liquid metal naturally conforms to the tube's deformation without requiring complex deposition processes.
Solution Approach 2:
The patent changes the physical state of the conductive material from solid (conventional) to liquid, which fundamentally simplifies the manufacturing process. The liquid metal can be easily injected and will automatically adapt to the elastomer tube's shape and deformation, eliminating the need for complex deposition and transfer printing methods.
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 microtube sensor achieves high sensitivity and durability, allowing for imperceptible and continuous monitoring of mechanical perturbations, such as arterial pulse waves, with potential applications in healthcare, prosthetics, and industrial settings, while reducing the need for additional signal conditioning and electronics components.
Implementation Method 1
The microtube sensor has the property that a change in electrical resistance of the liquid-state conductive element is indicative of a force-induced deformation of the flexible microtube
Data Source
AI summary
A soft, flexible microtube sensor and associated method of sensing force are described. A liquid metallic alloy is sealed within a microtube as thin as a strand of human hair to form the physical force sensing mechanism. The sensor is hardly distinguishable with the naked eye, and can be used for the continuous biomonitoring of physiological signals, such as unobtrusive pulse monitoring. Also described is a method of fabricating the microtube sensor and wearable devices incorporating one or more microtube sensors.