Flexible PCB Capacitive Sensor for Torque Measurement
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Solution Overview
Problem
Current mechanical sensors are inadequate for accurately measuring flex and torque in mechanical structures and joints, particularly in robotic devices, as they often require metallic housings and are not economically feasible for widespread integration.
Innovation Solution
A flexible sensor design featuring a printed circuit board with a capacitive structure and mechanical coupling sites, allowing the board to flex and measure changes in capacitance to determine mechanical flex or torque, which can be integrated into electronic printed circuit boards without metallic housings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mechanical sensors are used to measure flex and torque, then measurement capability is provided, but the sensors require metallic housings and are expensive
Solution Approach 1:
The patent replaces traditional mechanical sensing elements with a capacitive sensing system. The flex sensor uses capacitive plates that detect changes in capacitance due to flexing, while the torque sensor uses capacitive elements that detect rotational torque through capacitance changes. This substitution of mechanical measurement mechanisms with electrical/capacitive mechanisms eliminates the need for expensive metallic housings and complex mechanical components, thereby reducing manufacturing costs while maintaining measurement capability
Solution Approach 2:
The patent changes the measurement parameter from mechanical displacement or force to electrical capacitance. By measuring capacitance changes instead of direct mechanical parameters, the system can use inexpensive printed circuit board structures rather than precision mechanical components with metallic housings. This parameter transformation enables cost-effective manufacturing while preserving accurate measurement of flex and torque
2Measurement precision
If traditional mechanical sensors are used, then measurement capability is provided, but the sensors are not suitable for integration into electronic printed circuit boards
Solution Approach 1:
The patent creates sensors that serve dual purposes: they function as both structural components of the electronic device and as measurement sensors. The flex sensor is integrated directly into the printed circuit board structure, allowing the PCB itself to serve as the sensor substrate. The torque sensor is integrated into rotational joints of the robotic device, combining structural and sensing functions. This multi-functionality enables seamless integration into electronic printed circuit boards and robotic systems without requiring separate sensor housings or mounting structures
Solution Approach 2:
The patent merges the sensor functionality with the existing structural components of the device. The capacitive flex sensor is combined with the printed circuit board layers, eliminating the need for separate sensor assemblies. The torque sensor is merged with the rotational joint structure, using the joint's mechanical elements as part of the sensing mechanism. This merging approach enables direct integration into electronic printed circuit boards and mechanical structures
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 flexible sensor provides economically inexpensive and effective measurement of flex and torque, enabling its easy incorporation into robotic devices and other mechanical systems, while minimizing environmental effects on displacement measurements.
Implementation Method 1
The control circuit is configured to measure variations in a capacitance between the first edge electrode and the second edge electrode
Implementation Method 2
The slot is configured to permit the PCB to flex so as to vary a relative position of the first edge with respect to the second edge
Data Source
AI summary
A flexible sensor that includes a printed circuit board (PCB), a capacitive structure on the PCB, and mechanical coupling sites. The PCB includes a slot extending from an outer edge of the PCB to an inner portion of the PCB, and the slot defines a first edge and a second edge facing the first edge. The first and second edges are separated by a gap when the PCB is in an unflexed state. The slot is configured to permit the PCB to flex so as to vary a relative position of the first edge with respect to the second edge. The capacitive structure on the PCB includes a first edge electrode on a portion of the first edge of the PCB, and a second edge electrode on a portion of a second edge of PCB. The second edge electrode is aligned with the first edge electrode across the slot.