Appendix 4: Product Design Specifications

Client: Victor Haughton

Team Members: Briar Duffy, Angela Heppner, Elizabeth Nee, Jeff Phillips

December 12, 2001

1. Physical and Operational Characteristics

a. Performance requirements: The suture needle should be able to perform and accomplish any type of surgical task that current dermal suture needles can, in addition to including a pressure controlled arming mechanism that will push the sharp needle tip out of the hollow needle sheath. This mechanism allows the injury-causing tip to be normally inactivated, helping to prevent accidental needle sticks. Ideally, other needle sizes and shapes will be accommodated in future work.

b. Safety: A key safety feature will be the normally disarmed needle tip, which should be sharp and rigid enough to penetrate tissues with minimal trauma to the cells. The end of the needle tip must retract at least 0.5 mm into the sheath to ensure needle sticks will be prevented. Users will likely need proper training in order to use the new needle safely and most effectively.

c. Accuracy and Reliability:  Current suture needles rarely fail. Therefore, this design should meet or exceed current reliability. Despite the new arming feature, the needle tip must still remain rigid enough to resist buckling.

d. Life in Service: Due to the nature of the product, the needle would only be used once and then safely discarded.

e. Shelf Life: These needles would be stored in a hospital cabinet under controlled environmental conditions. However, an expiration date will be necessary because the balloon and fluid materials may degrade with time. Special packaging will be required to ensure sterility.

f. Operating Environment: The needle itself will be exposed to damaged body tissues and bodily fluids. It must be made of a material, such as 316L surgical steel, that will not cause any undesirable reactions with the tissues. Extreme care must also be given to the design because the operating environment that a surgeon would use the needle in is often stressful and hectic. Therefore, it is essential that the needle and arming mechanism be simple to use, so that surgeons can easily adapt to using the new needle design, and don’t have to waste precious time preparing the needle. The new safety feature allows the needle tip to be normally disarmed so that users will not injure themselves, even if they forget that they have a needle in their hand.

g. Ergonomics: The newly designed needle will be best received if it can perform the same types of stitches and be manipulated in the same manner as current needles. Although the current design affords the user flexibility as to how the device is held, more investigation is needed to determine if the needle will be able to pierce tissue when a normal amount of force is applied to it.

h. Size: For the scope of this course, a standard half-circle needle with a diameter of approximately 32 mm (1.25 in.) will be the focus for prototype design. Ideally, other needle sizes and shapes will be accommodated in future work.

i. Weight: The weight will depend on the size of the needle. The disarming mechanism should not add any excessive weight to the needle that would interfere with its ease of use.

j. Materials: The needle will most likely be made from a non-allergenic metal that is rigid enough to resist buckling, flexible enough to resist breaking, able to preserve sterility, able to maintain a sharp edge, and resist corrosion. The balloon arming mechanism may be produced from a medical grade plastic or rubber material that possesses the same properties as the metal.

k. Aesthetics, Appearance, and Finish:  Function will be more important than appearance, but the needle tip will likely be produced in a highly visible color to help attract attention to it, when it is armed. The finish should be smooth to minimize additional tissue trauma.

2. Production Characteristics

a. Quantity: Eventually, these needles will be mass-produced, so the design ideally should consist of parts that can be easily produced with little intricate or manual labor. Additionally, must be highly reproducible, with tight tolerances, so that little variance exists from needle to needle.

b. Target Product Cost: The redesigned needle will probably cost slightly more than current needles, because of its improved safety features. Even if the redesigned needle were to be more expensive than conventional needles, the additional features may make it desirable in certain niche markets.

3. Miscellaneous

a. Standards and Specifications: FDA approval will be required.

b. Customer: The redesigned needle must not interfere with a surgeon's preferred suturing technique.