Torque-Driven Drug Injector With Damped Plunger and Particle Filtration
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Solution Overview
Problem
Existing injector systems using coil springs for actuation face issues such as abrupt contact with medicament storage, leading to user discomfort and potential damage, and high shear rates on drugs due to excessive energy, along with the risk of contaminating medicaments with dispersed particles.
Innovation Solution
A torque-driven injector system incorporating a tightly wound torque spring and a damper mechanism to control the torque exertion, combined with a filter member to restrict unwanted particles, ensuring smooth and controlled medicament delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a coil spring is used to provide actuation energy for drug delivery, then the device achieves simplicity and automation, but excessive energy is input at the beginning of plunger stroke causing abrupt contact and user discomfort
Solution Approach 1:
The patent applies beforehand cushioning by introducing a damper mechanism that anticipates and mitigates the abrupt contact between the plunger and medicament storage portion. The damper is positioned to engage before the plunger reaches the storage portion, gradually absorbing the excess energy from the spring and preventing the harmful 'slap' effect that would otherwise occur at the end of the air gap traversal.
Solution Approach 2:
The patent changes the energy delivery parameters by using a damper mechanism that transforms the constant force output of the spring into a controlled, decreasing force profile. The damper modifies the force-displacement relationship, allowing high initial force to overcome friction and start movement, then progressively reducing force to prevent abrupt contact and excessive shear rates on the drug product.
2Force
If springs with higher spring constants are used to deliver higher viscosity drugs, then sufficient force is achieved, but excessive shear rates and potential drug product damage occur
Solution Approach 1:
The damper mechanism changes the force application parameters by introducing a velocity-dependent resistance element. This allows the system to use higher spring constants for viscous drugs while the damper controls the rate of force application, maintaining sufficient total force for drug delivery while limiting instantaneous shear rates that would damage the drug product.
Solution Approach 2:
The damper acts as an intermediary between the high-force spring and the drug product, mediating the force transmission. It allows the spring to generate high forces needed for viscous drugs while progressively delivering that force to prevent excessive shear rates, protecting the drug product from damage.
3Speed
If a plunger traverses an air gap with large spring forces, then the plunger reaches the medicament storage portion, but abrupt contact and mechanical bumps occur
Solution Approach 1:
The damper mechanism provides beforehand cushioning by being positioned to engage the plunger before it reaches the medicament storage portion. As the plunger traverses the air gap, the damper gradually absorbs kinetic energy and provides resistance, preventing the abrupt contact and mechanical bumps that would occur without it.
Solution Approach 2:
The damper serves as an intermediary between the moving plunger and the stationary storage portion, absorbing the impact energy and preventing direct abrupt contact. It mediates the transition from high-speed traversal to gentle engagement with the medicament.
4Ease of manufacture
If pre-filled syringes are filled without filtration, then filling process is simple, but unwanted particles disperse within the medicament causing contamination
Solution Approach 1:
The filter member acts as an intermediary between the filling process and the final medicament product. It allows the filling process to remain relatively simple while intercepting and removing unwanted particles before they can disperse throughout the medicament, preventing contamination without requiring complex filtration infrastructure.
Solution Approach 2:
The filter member extracts unwanted particles from the medicament during or after filling. By positioning the filter in the flow path, it selectively removes particulate contaminants while allowing the liquid medicament to pass through, separating the harmful particles from the therapeutic product.
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 system reduces user discomfort by minimizing abrupt movements and potential damage, maintains consistent torque throughout the actuation process, and effectively filters out particles, ensuring safe and comfortable medicament administration.
Implementation Method 1
The actuating mechanism includes a torque spring that exerts a torque that urges the medicament through the filter member to be injected into the user
Implementation Method 2
The actuating mechanism further includes a damper mechanism that exerts an opposing force or torque to dampen the torque exerted by the torque spring
Implementation Method 3
The filter member restricts particles dispersed within the medicament from entering the needle assembly
Data Source
AI summary
An injector includes a housing having a syringe assembly and an actuating mechanism at least partially disposed within the housing. The syringe assembly includes a syringe barrel that stores a medicament to be injected into a user, a needle assembly, and a filter member disposed adjacent to the needle assembly. The actuating mechanism is operatively coupled to the syringe assembly and includes a torque spring that exerts a torque to urge the medicament through the filter member to be injected into the user. The actuating mechanism further includes a damper mechanism that exerts an opposing force to dampen the motion exerted by the torque spring.