Gradient Piezoresistive Strip for High-Resolution Pressure Sensing
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Solution Overview
Problem
Smart patches, such as electronic skin, face challenges in multi-pixel integration, complicated wiring, and energy consumption due to the sensitivity differences between pixels, limiting pressure resolution and detection capabilities.
Innovation Solution
A pressure sensing device with first and second sensing elements having different gradients, coupled with a sensing circuit to determine the load and location of pressure events, utilizing piezoresistive materials like nanoparticles or nanotubes, and featuring a flexible substrate with GNP strips having anti-parallel sensitivity gradients for enhanced sensitivity and reduced readout data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixelated array of strain/pressure sensors is used, then pressure sensing capability is achieved, but resolution is limited by pixel size and sensitivity differences between pixels reduce overall pressure resolution
Solution Approach 1:
The patent changes the fundamental parameter of the sensing element from discrete pixels to a continuous strip with gradient properties. The strip features a gradual change in thickness, width, or material composition along its length, creating a continuous distribution of sensitivity values rather than discrete pixel responses. This allows for higher resolution pressure detection without being constrained by pixel size, as the gradient provides unique sensitivity signatures at different positions along the strip.
Solution Approach 2:
The patent introduces asymmetry through the gradient structure of the sensing strip. The non-uniform thickness, width, or material distribution creates an asymmetric sensitivity profile along the strip length. This asymmetric gradient ensures that each position on the strip has a distinct sensitivity characteristic, enabling precise location identification and pressure resolution without requiring multiple identical pixels.
2Area of stationary object
If 10×10 pixelated smart patch is implemented, then pressure sensing coverage is achieved, but 200-300 wiring devices and 100 electrical measurement devices are required, increasing energy consumption and cost
Solution Approach 1:
The patent merges multiple discrete sensing elements into a single continuous sensing strip with gradient properties. Instead of requiring separate wiring and measurement circuits for each pixel in a 10×10 array, the gradient strip functions as one integrated sensing element. This consolidation dramatically reduces the number of wiring devices and measurement circuits needed, thereby reducing energy consumption and system complexity while maintaining comprehensive sensing coverage.
Solution Approach 2:
The gradient sensing strip serves multiple functions simultaneously: it provides pressure sensing across its entire length, identifies the location of applied pressure through its gradient signature, and determines pressure magnitude. This multi-functionality eliminates the need for separate dedicated circuits for each sensing function that would be required in a pixelated array, reducing overall energy consumption.
3Area of stationary object
If pixelated array with multiple pixels is used, then sensing coverage is achieved, but complicated wiring and associated measurement devices are required
Solution Approach 1:
The patent combines the functionality of multiple pixels into a single gradient-based sensing strip. This merging approach requires only one set of wiring connections and measurement devices rather than the complex wiring networks needed for individual pixel access in a multi-pixel array, significantly simplifying the overall device architecture.
Solution Approach 2:
The patent transitions from a two-dimensional pixelated array to a one-dimensional gradient strip. This dimensional reduction simplifies the wiring architecture by eliminating the need for row and column addressing circuits required in 2D arrays. The gradient encoding along the single dimension of the strip provides sufficient information for both location and pressure magnitude detection.
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 solution achieves highly sensitive prediction of both load and position along the sensing strip, reducing energy consumption and complexity, while maintaining sensitivity to environmental stimuli like temperature and humidity, and enabling accurate detection of small loads and precise location identification.
Implementation Method 1
both the load and position on which the load is applied, can be predicted based on the resistance of the two GSSs. The GSSs may be made of or include one or more piezoresistive materials.
Implementation Method 2
The sensitivity of GNP-based sensors to strain stems mainly from the tunneling mechanism between neighboring nanoparticles. When a GNP film is deposited on a flexible substrate, deformation of the substrate affects the inter-particle distance in the film and the resistance changes accordingly.
Data Source
AI summary
A pressure sensing device having a first sensing element, a second sensing element and a sensing circuit. The first and second sensing elements have one or more piezoresistive materials. The first sensing element has a first gradient along a longitudinal axis thereof having a first direction. The second sensing element has a second gradient along a longitudinal axis thereof having a second direction. The first direction of the first gradient is opposite to the second direction of the second gradient. The sensing circuit is (a) coupled to the first and second sensing elements and (b) arranged to sense at least one out of resistance and conductance of the first and second sensing elements to determine a magnitude and a location of a pressure applied on the first and second sensing elements along the longitudinal axes thereof.