Foil Force Sensor Structure for Stable Miniaturized Load Detection
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Solution Overview
Problem
Current force sensors face challenges in miniaturization and flexibility, with existing technologies being temperature-dependent and sensitive to environmental influences, requiring complex calibration and calibration drift over time.
Innovation Solution
A foil-based force sensor with a direct force transducer comprising a composite element of conductive electrodes on a polymer film, partially covered by a polymer nanocomposite, and a direct force transducer mounted outside or above the electrode area, allowing elastic deformation for precise force measurement via impedance and resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauge-based sensors are used, then sensitivity and linearity are improved, but temperature dependence and calibration requirements worsen
Solution Approach 1:
The patent replaces traditional strain gauge-based mechanical measurement systems with a capacitive sensing system that measures force through changes in capacitance between electrodes and a conductive membrane. This substitution eliminates the temperature-dependent resistance changes inherent in strain gauges while maintaining high sensitivity through electrical field interactions.
Solution Approach 2:
The patent employs a composite structure combining a polymer membrane with conductive materials (such as conductive polymers, metal coatings, or nanoparticle composites) to create a force-sensitive element that exhibits stable electrical properties across temperature ranges while maintaining high capacitive sensitivity to force applied.
2Speed
If piezoelectric sensors are used, then dynamic force measurement capability is improved, but static force measurement capability worsens
Solution Approach 1:
The patent replaces piezoelectric mechanical stress-to-electricity conversion with a capacitive sensing mechanism that continuously monitors the electrical field between fixed electrodes and a deformable conductive membrane. This allows simultaneous measurement of both dynamic forces (through rapid capacitance changes) and static forces (through sustained capacitance values), eliminating the static measurement limitation of piezoelectric sensors.
3Volume of moving object
If force sensors are miniaturized, then application versatility is improved, but manufacturing precision and calibration difficulty worsen
Solution Approach 1:
The patent implements self-calibration functionality where the sensor automatically determines its sensitivity factor by applying a known reference force and measuring the resulting capacitance change, then storing this calibration data for subsequent measurements. This self-service approach eliminates the need for complex external calibration equipment and maintains high precision even in miniaturized formats.
Solution Approach 2:
The patent designs a universal sensor platform using standard interdigital electrode patterns and conductive membrane structures that can be manufactured using common PCB and thin-film deposition techniques. This universal design allows the same basic structure to be scaled to different sizes and applications while maintaining consistent manufacturing tolerances and calibration procedures.
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 sensor achieves high sensitivity and adaptability to different applications with customizable force measurement ranges, maintaining accuracy and robustness against environmental factors.
Implementation Method 1
the direct force transducer elastically deforming according to its material properties. This deformation causes a direct mechanical load on the polymer nanocomposite, which also undergoes elastic compression
Implementation Method 2
The compression changes the electrical field and/or the electrical resistance measured between at least two conductive traces
Data Source
AI summary
A foil sensor for force detection with direct force transducer, with a corresponding electrical contact line for detecting forces and force loads, wherein electrical signal can be derived from the foil sensor. At least two conductive electrodes are applied to the plastic film material which have a contacting area on the leads. On this surface of the plastic film material, a direct force transducer is applied, which absorbs the mechanical forces and deforms elastically when force is applied. A polymer nanocomposite material is also placed on this surface in such a way that the conductive electrodes are covered by the polymer nanocomposite material, which does not or only partially touches the direct force transducer, whereby a free area is formed between the material and transducer. The elastic material compression of the polymer nanocomposite can be detected by an impedance and/or electrical resistance measurement via the conductive electrodes.