Technical notes

PA (polyamide) vs PI (polyimide) — choosing a catheter material

Choose PA when flexibility, kink resistance and cost come first; choose PI when thin-wall strength, thermal stability and dimensional precision are decisive. Continuous service 100–120 °C against 250–300 °C, tensile 50–90 MPa against 120–200 MPa, and PI costs 5–10× more.

A guide to CNC machining medical PEEK

Cutting speed 100–150 m/min, sharp carbide or PCD tooling, and keeping it cool are the basics. Medical work machines USP Class VI and ISO 10993 stock in an ISO 7 or better cleanroom with batch traceability. Tolerance on small parts is typically ±0.05 mm.

Catheter design guide — material, layers, tolerance

Push force, torque, kink resistance and lubricity all compete for the same wall thickness. Fixing the clinical task and the anatomical path first, then settling liner, reinforcement and jacket, is the faster order. Braid gives torque; coil gives flexibility.

PEEK biocompatibility — what an engineer should know

PEEK has no plasticizers or leachable additives, is BPA-free, and passes ISO 10993 cytotoxicity, sensitization and irritation testing. Its 3.6 GPa modulus is close to cancellous bone, so stress shielding is low, and properties hold through repeated autoclave and gamma sterilization.

Medical PI tubing — seven things an engineer should check

Tensile strength at thin wall, thermal stability, chemical resistance, dimensional tolerance, biocompatibility, predictable bending behaviour, and compatibility with braiding and coating processes. These seven are why PI keeps being chosen as a microcatheter liner.