Deflectable Contact Arm for Low-Force Electrical Connection
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Solution Overview
Problem
Existing blood glucose meters with thin film-coated test strips face issues with connector abrasion and unreliable connections due to residual stresses and poor dimensional control, leading to reduced reliability and increased force requirements for insertion, which can damage the thin gold coatings and result in less accurate measurements.
Innovation Solution
A connector assembly with a contact arm that extends entirely in the insertion direction, featuring a deflectable beam portion and a rigid beam portion, and a contact arm with a convexly curved surface to minimize pressure area and reduce friction, ensuring a low-force electrical contact and improved dimensional control, thereby reducing the risk of gold layer removal and enhancing connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bent wire form connector is used to provide flexibility, then the connector can accommodate insertion motion, but residual stresses are introduced and dimensional control at the clearance point deteriorates, requiring greater insertion force
Solution Approach 1:
The connector is divided into two separate functional components: a flexible beam portion that accommodates insertion motion and a separate contact portion that maintains electrical contact. This segmentation allows each component to optimize its function without compromising the other, eliminating the need for residual stresses in a single bent wire structure.
Solution Approach 2:
Instead of using a bent wire form that requires the test strip to displace the connector, the invention inverts the approach by having the flexible beam actively engage and trail along the test strip surface. This reversal of the engagement mechanism reduces the force required for insertion while maintaining reliable electrical contact.
2Manufacturing precision
If the connector is positioned closer to the test strip to improve dimensional control, then contact positioning is improved, but greater force is required to displace the connector, increasing potential for gold layer removal
Solution Approach 1:
The flexible beam is designed with non-uniform cross-sectional dimensions, being thicker at the base for structural support and thinner at the contact portion for reduced friction. This local variation in geometry allows the beam to maintain dimensional control for proper contact positioning while requiring minimal force for insertion and reducing stress on the gold coating.
3Loss of substance
If thin film gold coatings are used on test strip contact pads, then miniaturization and cost reduction are achieved, but the coatings are prone to scratching and removal by current connectors
Solution Approach 1:
The invention replaces the traditional mechanical pressing contact with a trailing contact mechanism where the flexible beam contacts the test strip and moves along with it during insertion. This substitution eliminates the high-friction pressing action that causes scratching, while maintaining reliable electrical connection through continuous trailing contact.
Solution Approach 2:
The contact mechanism changes from a high-force pressing action to a low-force trailing contact. By altering the mechanical parameters of the contact interaction (force, friction, contact duration), the invention protects the thin gold coating while ensuring reliable electrical connection for measurement.
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 a low-force, reliable electrical connection with reduced friction and stress, minimizing the risk of gold layer damage and ensuring accurate measurements, even with repeated insertions, by using a contact arm design that trails along the test strip and maintains contact without bending, thus reducing the force required for insertion.
Implementation Method 1
a contact arm with a convexly curved surface to minimize pressure area and reduce friction
Data Source
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AI summary
A system for measuring an analyte of interest in a biological fluid includes a test strip for receiving a sample of the biological fluid having multiple contacts formed thereon. A test device includes a circuit board having multiple conducting strips. A connector assembly is fixed to the circuit board and receives the test strip as the test strip moves in an insertion direction to a test position. The connector assembly includes a connector assembly body and multiple conductors. Each of the conductors includes a conductor contact body fixedly connected to the connector assembly body, and a contact arm integrally connected to the conductor contact body and freely extending entirely in the insertion direction. The contact arm is deflected when directly contacted by one of the multiple contacts of the test strip.