Bistable Drive Mechanism for Rapid Needle Insertion
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Solution Overview
Problem
Administering injections is challenging due to difficulties in avoiding needle tilting and bending, leading to pain and slow insertion processes, which existing technologies have not adequately addressed.
Innovation Solution
A bistable drive mechanism with a pivoted link and spring biasing, combined with a forked needle retainer and motor-driven wheel, allows for precise and rapid needle movement between retracted and extended positions, reducing pain and improving user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If manual needle insertion is used, then the device complexity is low, but the needle insertion speed is slow and needle tilting/bending cannot be avoided
Solution Approach 1:
The drive mechanism uses a bistable mechanism with two stable positions (needle retracted and needle extended) and an unstable transitional position. The spring biases the link toward stable positions, while the trigger unit can dynamically shift the system between states, enabling rapid needle deployment when needed while maintaining simplicity at rest.
Solution Approach 2:
The drive mechanism is divided into distinct functional components: a pivoted link with two stable positions, a spring biasing element, and a trigger unit. This segmentation allows each component to perform its specific function efficiently, contributing to overall rapid and reliable needle insertion.
2Productivity
If rapid needle insertion is implemented, then the needle insertion speed increases, but the risk of needle tilting and bending increases
Solution Approach 1:
The bistable mechanism ensures that the needle is held firmly in either the retracted or extended position, eliminating intermediate unstable states that could cause tilting. The rapid transition between stable states occurs in a controlled manner, maintaining needle alignment during insertion.
Solution Approach 2:
The spring biasing provides continuous mechanical feedback to the pivoted link, ensuring it returns to a stable position after being triggered. This feedback mechanism guarantees reliable needle deployment and retraction, preventing partial or tilted insertions.
3Ease of operation
If a bistable mechanism with trigger unit is used, then the needle insertion speed and precision improve, but the device complexity increases
Solution Approach 1:
The spring biasing automatically returns the pivoted link to its stable position after triggering, eliminating the need for additional reset mechanisms. The trigger unit simply initiates the transition; the spring handles the return journey, simplifying the overall control system.
Solution Approach 2:
The pivoted link serves multiple functions: it acts as the driving element for needle deployment, provides structural support for the spring biasing, and serves as the connection point for the trigger unit. This multi-functionality reduces the number of separate components needed.
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 enables high-speed, precise needle guidance, reducing patient discomfort and increasing consumer acceptance, while maintaining mechanical robustness and low manufacturing costs, with a fault-tolerant system for both manual and motor-powered operations.
Implementation Method 1
a spring biasing the link out of the transitional central position
Implementation Method 2
The drive has actuator wires on the basis of a shape memory alloy (SMA) for control of the pricking movement by a change of wire length. The actuator wire forms a feed unit for forward movement of the pricking unit through heat-activated contraction.
Implementation Method 3
The drive has an actuator formed by an electro-active polymer.
Data Source
AI summary
The invention relates to a drive mechanism (9) for a needle insertion arrangement (1), the drive mechanism (9) being arranged as a bistable mechanism with at least one pivoted link (10, 11) having two stable end positions (LEP, UEP) and an instable transitional central position (CP), the drive mechanism (9) further comprising a spring (12) biasing the link (10, 11) out of the transitional central position (CP), wherein at least one trigger unit (17, 21) is arranged for moving the link (10, 11) out of at least one of the stable end positions (LEP, UEP) towards and beyond the transitional central position (CP) against the bias of the spring (12).