Effect of Teflon coating

Teflon (Polytetrafluoroethylene / PTFE / FEP / PFA) coating is celebrated for its extraordinary non-stick properties, chemical inertness, and thermal stability. In precision fluid handling and medical diagnostic equipment, Teflon coatings ensure liquid droplets detach instantly without droplet hanging or residue.

Figure 1: King Square Hydrophobic Teflon-Coated Reagent Sampling Needle

1. Outstanding Physical and Chemical Properties

• Ultra-Low Surface Energy: Surface energy is as low as 18 mN/m. Almost all organic and aqueous liquids exhibit large contact angles (> 110°), enabling rapid droplet roll-off.
• Exceptional Chemical Inertness: Completely immune to strong acids (HCl, H2SO4, HNO3), strong alkalis (NaOH), and aggressive organic solvents used in biochemistry cleansers.
• Broad Operating Temperature Range: Continuous operational stability from -190°C up to +260°C.
• Low Dynamic Friction: Dynamic friction coefficient between 0.05 to 0.10, ensuring minimal wear during rubber septum penetrations.
• Dielectric Isolation: High dielectric strength preventing electrical crosstalk in capacitive liquid level detection circuits.

2. Application in Medical Sampling Needles

When liquid drops hang at the needle orifice, dispensing accuracy degrades and consecutive tests suffer contamination. A micro-thickness Teflon coating (typically 10 μm to 25 μm) applied around the needle tip prevents droplet adhesion, ensuring exact droplet volume delivery down to 0.1 μL.