The cornerstone and foundation of a multitude of surgical procedures, medical needles are often improperly viewed as a “commodity” rather than precision-engineered devices. However, a growing number of medical needles are taking a major role in today’s state-of-the-art surgical devices, and their function as a “delivery device” for specialized procedures is very critical.
The first step for any medical needle based project should be “DEFINE”, a true brainstorming session aimed at identifying Functional and Manufacturing aspects of design and performance so that they can be matched with the expertise and capabilities of the contract manufacturer.
The following are 5 tips on how to make better medical needles:
1.) Optimize for the Application
- Fluid vs. Solid Delivery - What is being delivered? Does the diameter of the deliverable require special consideration for the tubing I.D.?
- Surface finish requirements (Ra) could play a significant role from a multitude of parameters including cleanliness, ease-of-delivery, damage to the implant etc.
- Coring vs. non-coring tip configuration – is this a required differentiator and how critical is the non-coring aspect?
- Material selection to meet application requirements (non-magnetic, MRI, hardness, chemical composition)
2.) Material & Needle Tip Consideration:
- Which part of the body is being penetrated? (tissue vs. bone)
- Number of insertions per procedure? Is the needle being used on a one-time basis or expected to perform in multiple insertions? This aspect impacts both material selection and tip geometry
- Flat vs. Lancet Grind? Standard vs. Short bevel? Non-Coring? Needle “sharpness” needs to be identified from a functional standpoint.
- Material selection to meet tip requirements and edge retention
3.) Performance Criteria
- PF - Penetration Force or FTF (Force To Fire). Although one would expect a needle that requires low penetration force, many of today’s applications demand a performance criterion that is above the acceptable norm. Consideration should be given to:
- -> Why is penetration force critical in this application? (tissue trauma, site location, competitor’s performance)
- Straightness/alignment of cannula to hub or tubing/wire in general.
- -> Why is this critical feature and what is the impact on patient safety, inspection, assembly, and handling?
4.) Inspection Criteria
- Magnification – requirement vs. industry standards for in-process and/or final inspection. Why is the additional magnification necessary and is it justified from a cost standpoint.
- Sampling Plans – should be discussed up front along with all supporting documents to assure ultimate process capability.
- Cleanliness – define “clean” along with verification parameters.
This critical discussion item should address
- tip protection to protect sharps
- in-transit protection
- receiving requirements and handling
- Expectation for cleanroom receiving or processing
The foundation of success in surgical device manufacturing is based on careful and detailed upfront evaluation of all design, functional and performance criteria. The five tips above will help make a better medical needle.