Flexible Touch Sensing With Deformable Material
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Solution Overview
Problem
Existing stretchable soft sensors face challenges in inexpensive fabrication and maintaining contact localization during material deformation, due to high rebound elasticity and slow recovery of sensing signals in carbon-filled silicone rubber.
Innovation Solution
The implementation of an adaptive multi-sensing process using electrical impedance tomography (EIT) and a learning-based support vector machine (SVM) to achieve real-time contact localization and deformation awareness, allowing for single-volume fabrication and instant interaction without invasive electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If carbon-filled silicone rubber is used for soft sensor fabrication, then flexibility and stretchability are improved, but real-time sensing capability deteriorates due to rebound elasticity and slow signal recovery
Solution Approach 1:
The patent changes the sensing principle from resistive measurement to capacitive measurement. By measuring capacitance between electrodes rather than resistance through the material, the system achieves real-time sensing capability while maintaining the flexibility and stretchability of carbon-filled silicone rubber. Capacitive sensing responds instantaneously to touch without the slow recovery characteristic of resistive materials.
Solution Approach 2:
The patent replaces the mechanical/resistive sensing mechanism with an electrical capacitive sensing mechanism. Instead of relying on the physical deformation and resistance change of the elastomer material, the system uses electric field-based capacitive sensing that provides immediate response regardless of the material's elastic recovery characteristics.
2Measurement precision
If invasive electronics and interior elements are placed within the sensor material, then sensing precision is improved, but fabrication complexity and cost increase
Solution Approach 1:
The patent makes the elastomer material itself serve multiple functions: it acts as both the structural substrate and the sensing element. By incorporating conductive particles throughout the material, the entire surface becomes sensitive to touch, eliminating the need for separate sensing components and invasive electronics while maintaining precise contact localization capability.
Solution Approach 2:
The patent uses a simplified electrode arrangement on the surface that replicates the sensing function without requiring complex interior electronics. The capacitive sensing approach creates an electrical field that extends into the material, allowing surface electrodes to detect contact locations accurately without invasive internal components.
3Reliability
If multi-step fabrication processes are used for soft sensors, then sensing performance is improved, but manufacturing cost and production time increase
Solution Approach 1:
The patent merges the sensing functionality directly into the elastomer material formulation by incorporating conductive particles during material mixing. This single-step integration eliminates the need for separate sensing layer fabrication, electrode embedding, and wiring processes, thereby simplifying manufacturing while maintaining reliable sensing performance.
Solution Approach 2:
The elastomer material with embedded conductive particles serves its own sensing function without requiring additional fabrication steps for separate sensing components. The material self-organizes the sensing capability through its inherent conductivity distribution, enabling simple fabrication processes to produce functional sensors with reliable performance.
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
Enables low-cost, customizable, and real-time continuous touch input with maintained and restored contact localization during and after material deformation, facilitating easy deployment and use.
Implementation Method 1
the presently disclosed device utilizes carbon-filled liquid silicone rubber, a non-toxic piezoresistive elastomer material
Implementation Method 2
This is mainly due to a rebound elasticity of the material, which causes a slow-recovery of the sensing signals after the material deformations
Data Source
AI summary
A sensing system includes a base material, a plurality of electrodes, a capacitive sensing channel and a controller. The stretchable base material has a resistance distribution that changes in response to being mechanically deformed as a result of a human body contact. The base material has a rebound elasticity. The electrodes are attached to a perimeter of the base material, the capacitive sensing channel is attached to the base material. The controller is operatively connected to the plurality of electrodes and the capacitive sensing channel. The controller is configured to measure instantaneous voltage measurements from the plurality of electrodes, and determine whether the base material is mechanically deformed based on the instantaneous voltage measurements using a support vector machine classifier.