Nasal Spray Device Interlock Mechanism for Threshold Force Actuation
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Solution Overview
Problem
Existing nasal delivery devices often fail to ensure a therapeutically effective spray of medicaments due to insufficient delivery speed, leading to ejection of the liquid as a stream or drop instead of a spray, and there are challenges in confirming the complete delivery of the medicament dose.
Innovation Solution
A nasal delivery device with a pusher mechanism that includes interlocking parts to ensure a threshold actuating force is exceeded, allowing the pusher to move at a speed that generates a spray, featuring a resilient arm and surface interlock system to prevent inadvertent actuation and ensure proper dosage delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simple pusher mechanism is used without interlock, then the device is easier to operate, but the delivery speed cannot ensure spray generation
Solution Approach 1:
An interlock mechanism acts as an intermediary between the pusher and the plunger. The interlock includes a resilient arm with a protrusion that engages a recess in the plunger, preventing movement until sufficient force is applied. This mediator ensures that only when the user exceeds the threshold force does the pusher move at the required speed to generate spray, thus resolving the contradiction between ease of operation and delivery speed.
2Device complexity
If no interlock mechanism is used, then the device structure is simpler, but inadvertent actuation cannot be prevented
Solution Approach 1:
The interlock mechanism is pre-configured in a locked state where the resilient arm's protrusion engages with the plunger's recess. This preliminary locking action prevents any movement of the pusher before the user intentionally applies sufficient force. The interlock must be actively overcome to enable operation, thus preventing inadvertent actuation while maintaining relatively simple device structure.
3Ease of operation
If the pusher can move freely without threshold force requirement, then the device is easier to activate, but spray generation cannot be ensured
Solution Approach 1:
The interlock mechanism changes the force parameter required to activate the device. By designing the resilient arm with specific stiffness and the engagement geometry, a threshold force parameter is established. Below this threshold, the interlock remains engaged; above it, the pusher moves freely at sufficient speed. This parameter change ensures spray generation precision while maintaining ease of operation through clear tactile feedback.
4Speed
If a resilient interlock mechanism is added, then spray generation is ensured, but the device complexity increases
Solution Approach 1:
The interlock function is extracted as a separate, modular resilient arm component rather than being integrated into the main pusher body. This allows the interlock to be a simple, standalone element with minimal parts - essentially a spring-loaded lever with engagement features. By extracting this function, the overall device complexity increases only minimally while achieving the required spray generation speed.
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 device effectively generates a spray of medicament by ensuring a minimum activation speed is met, ensuring complete and accurate delivery of the medicament dose, preventing accidental actuation during storage and shipping.
Implementation Method 1
The movable interlocking part is resiliently movable when the threshold actuating force is exceeded to unblock the movement of the pusher relative to the body
Data Source
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AI summary
A delivery device for delivery of a medicament to a user including a container defining a reservoir storing the medicament, a body in which the container is received, a spray nozzle arranged on one of the body and the container for receiving medicament expelled from the container, and a pusher actuatable for pushing the medicament from the container reservoir through the nozzle, said pusher being movable from a rest position to a fully activated position relative to said body in response to an actuating force. The assembly is particularly applicable to nasal syringes where it is desirable to deliver the medicament in the form of a spray.