Drug Delivery Drive Unit with Force Adaption Mechanism
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Solution Overview
Problem
Current drug delivery devices, particularly auto-injectors driven by springs, face challenges such as variable dose delivery due to changing spring force over the injection cycle, which can lead to inconsistent medication administration, especially for patients with dexterity issues or elderly users.
Innovation Solution
A drive unit for drug delivery devices featuring a drive spring and a drive force adaption mechanism that modifies the spring force, allowing for adjustable injection time and adaptation to drug viscosity, comprising disk-shaped inserts, cams, gearboxes, resilient beams, or friction mechanisms to ensure consistent drug delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a spring is used to drive the plunger in an auto-injector, then the injection can be administered automatically without continuous user pressure, but the spring force varies during the injection cycle leading to inconsistent dose delivery
Solution Approach 1:
The patent applies dynamics by making the drive mechanism adjustable during operation. The drive force adaption mechanism allows the spring pre-compression to be modified during the injection cycle, enabling the system to adapt to changing viscosity conditions and maintain consistent delivery rates throughout the injection process
Solution Approach 2:
The patent changes physical parameters by allowing adjustment of the spring's pre-compression force and injection rate. The drive force adaption mechanism modifies the spring force parameter dynamically, and the system can adjust injection parameters based on detected viscosity variations, ensuring reliable dose delivery under varying conditions
2Reliability
If the spring force is increased to ensure complete dose delivery, then the injection can overcome high viscosity drugs, but the injection force may be too high for elderly or dexterity-impaired users
Solution Approach 1:
The patent introduces an intermediary mechanism between the user activation and the actual injection force delivery. The drive force adaption mechanism acts as a mediator that decouples the activation force from the injection force, allowing users to trigger the injection with minimal force while the mechanism subsequently delivers the full force needed to overcome high viscosity drugs
Solution Approach 2:
The patent applies preliminary action by pre-compressing the spring to a controlled extent before injection, and the drive force adaption mechanism prepares the optimal force configuration in advance. This allows the system to deliver high forces when needed without requiring the user to apply high activation forces
3Productivity
If the injection is driven quickly to reduce injection time, then productivity is improved, but the variable spring force causes irregular injection timing and potential dose inconsistency
Solution Approach 1:
The patent implements feedback by detecting the actual injection progress and viscosity conditions, then using this information to adjust the drive force through the adaption mechanism. This closed-loop control ensures that injection timing remains regular and predictable even at high speeds, maintaining both productivity and reliability
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 drive unit ensures a more regular injection time and adapts to the viscosity of the drug, allowing for adjustable injection speed, thereby improving the reliability and consistency of medication administration.
Implementation Method 1
A drive spring (5) is arranged for biasing the plunger (4) in a distal direction (D) relative the carrier (3)
Implementation Method 2
The drive force adaption mechanism is adapted to introduce a friction force opposing a force of the drive spring
Data Source
AI summary
Described is a drive unit (1) for a drug delivery device comprising a carrier (3), a plunger (4) arranged within the carrier (3) and slidable in a direction of a longitudinal axis (A), a drive spring (5) arranged for biasing the plunger (4) in a distal direction (D) relative the carrier (3), and a drive force adaption mechanism (22) for modifying a force exerted by the drive spring (5) on the plunger (4).