Piezoelectric Patch Sensor for Linear Muscle Movement Measurement
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Solution Overview
Problem
Conventional wearable textile sensors for muscle movement measurement are expensive, prone to signal non-linearity, and suffer from limited durability and slip issues when attached to the skin, leading to faulty sensing.
Innovation Solution
A piezoelectric patch sensor with an adhesive layer, integrated elastic sheet, and aligned piezoelectric fibers directly attached to the skin, connected via conductive wires to an interface circuit for reliable muscle movement measurement, capable of withstanding large deformations and minimizing mechanical constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional wearable textile sensors are embedded into fabrics using stitching or knitting techniques, then the sensing capability is integrated into the fabric, but the signal output becomes non-linear and repeatability decreases
Solution Approach 1:
The patent extracts the sensing function from the fabric structure itself and places it on a separate adhesive patch that contacts the skin directly. The piezoelectric yarn is contained within a compressed adhesive patch rather than being stitched into the fabric, separating the sensing element from the garment structure and enabling more accurate measurement of skin deformation.
Solution Approach 2:
The adhesive patch acts as an intermediary between the fabric and the skin, providing direct contact for accurate sensing while being replaceable. This intermediary layer transfers the mechanical deformation from the skin to the piezoelectric yarn more faithfully than fabric stitching, improving signal linearity.
2Adaptability or versatility
If multi-layered conductive polymer is used to construct a capacitance sensor, then flexible capacitance for deformation measurement is achieved, but a larger area is required to achieve the desired flexibility
Solution Approach 1:
The patent replaces the multi-layered conductive polymer capacitance sensing mechanism with a piezoelectric yarn-based sensing mechanism. The piezoelectric effect directly converts mechanical deformation into electrical signals, achieving comparable flexibility with a more compact sensor design that does not require large areas.
3Adaptability or versatility
If piezoelectric yarn is twisted and fabricated into a woven piezoelectric fabric, then the range of strain measurement can be very large, but the signal-to-strain distribution becomes highly non-linear and long term repeatability deteriorates
Solution Approach 1:
The patent extracts the piezoelectric yarn from the woven fabric structure and places it in a compressed adhesive patch configuration. This extraction preserves the large strain measurement capability while eliminating the non-linear signal distribution caused by the twisted yarn structure in woven fabrics.
Solution Approach 2:
The patent uses a thin adhesive patch structure to encapsulate the piezoelectric yarn, allowing the sensor to conform to skin deformation while maintaining signal linearity. The thin film structure enables direct transmission of skin strain to the piezoelectric element without the geometric non-linearities introduced by woven or twisted configurations.
4Reliability
If sensing-capable fabrics are fabricated with sufficient strength and chemical compatibility for industrial fabrication processes, then the fabric can withstand laundering cycles, but the cost increases significantly
Solution Approach 1:
The patent segments the sensing function from the garment fabric, placing it in a separate adhesive patch that can be disposed of after a single use. This eliminates the need for the expensive, durable construction required for reusable sensing fabrics, making single-use applications economically viable.
Solution Approach 2:
The patent embraces the disposable nature of the adhesive patch, using simpler, less expensive materials that do not need to withstand repeated laundering. The piezoelectric yarn in an adhesive patch is designed for single-use applications, eliminating the cost of durable construction while maintaining measurement accuracy during the usage period.
5Adaptability or versatility
If sensing means are embedded in fabrics, then the sensor can be integrated into compression garments, but slip between the fabric and skin occurs leading to faulty sensing
Solution Approach 1:
The patent extracts the sensing function from the compression garment fabric and places it in a separate adhesive patch that directly contacts the skin. This extraction eliminates the slip problem by providing a dedicated adhesive interface between the sensor and skin, while the compression garment serves only as a support structure.
Solution Approach 2:
The adhesive patch serves as an intermediary layer between the compression garment and the skin, providing a secure contact interface for accurate sensing. The adhesive properties of the patch prevent slip while allowing the compression garment to remain loose-fitting, improving both measurement accuracy and comfort.
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 provides accurate, linear, and repeatable muscle movement measurements with improved durability and reduced cost, allowing for single-use applications and effective signal transmission to a host processor for numerical analysis.
Implementation Method 1
the piezoelectric fibers in the measurement circuitry generating a corresponding signal
Data Source
AI summary
A piezoelectric patch sensor for measuring muscle movement of contraction and extension is disclosed. The sensor is elongated and directly attached to a skin site of a user for the measuring via an interface circuit connected to a host processor. The piezoelectric patch sensor has an adhesive layer with an adhesive bottom surface for firmly attaching to the skin site. An elastic sheet is integrated on top of the adhesive layer. A piezoelectric thread is further integrated on top of the elastic sheet and has a bundle of aligned piezoelectric fibers. The thread is electrically coupled to the interface circuit via a pair of conductive wires, forming a piezoelectric measurement circuitry. Muscle movement under the skin site shrinks or extends the piezoelectric patch sensor in its entirety along the direction of muscle movement due to a corresponding shrinking or extending movement of the skin firmly attached to the adhesive layer. Thus results in the piezoelectric fibers in the measurement circuitry generating a corresponding signal, which is relayed by the interface circuit to the host processor for calculating to derive the muscle movement.