For endoscopic biopsy needles, material determines the upper limit, while geometry defines the lower limit.

304/316L stainless steel: high strength, well-established processing, and low cost; 316L offers greater stability in corrosive and bodily fluid environments. For most conventional 19–22–25G designs, stainless steel remains the mainstream general-purpose solution, especially when the design goal is to achieve "sufficient rigidity to transmit force to the needle tip and ensure clean penetration."

NiTi (nitinol): its core value lies in "superelasticity/shape memory," making it suitable when you need the needle body to return to a straight configuration after navigating sharp bends, or when you want the tip assembly to have a certain safety margin of rebound. However, machining, grinding, and surface treatment of NiTi-requiring careful control of nickel release while maintaining surface integrity-are more demanding on the manufacturing process than with stainless steel. Manners includes NiTi as an optional material within its portfolio, evaluating and validating it on a project-by-project basis rather than replacing all needles with NiTi indiscriminately.

Design Point 1: The Needle Tip and the Biopsy Window are a Pair of Conflicting Elements

To achieve a larger sample size, the window is often extended; however, the longer the window, the more pronounced the "creasing/collapse tendency" of the needle under bending stress becomes, resulting in a sticky feel during pushing. Manners typically addresses this by using a more controlled laser-cut window combined with precision-edged finishing to achieve clean edges and smooth transitions, thereby reducing the impact on needle rigidity while maintaining the same window area.

Design Point 2: Surface = Invisible Performance

Even with the same material, the clinical feel of a coarse ground surface differs significantly from that of an electropolished surface: the latter offers lower friction, less mucosal drag, and is less likely to harbor contaminants. This is why endoscopic biopsy needles on Manners' production line almost always go through electropolishing and ultrasonic cleaning-these are not optional enhancements, but rather essential requirements for qualification.

Design Point 3: Use Coatings with Caution

Hydrophilic coatings can reduce friction and improve smoothness, but they require more rigorous validation of coating adhesion and particle shedding; otherwise, "slippery" may be achieved, yet particles could still enter the patient's body. For brands aiming for differentiation, a safer and more common approach is to first achieve extremely high consistency in substrate, geometry, polishing, and cleaning before considering coating upgrades.