The project “APC‑Greenprobe” aimed to replace the conventional polytetrafluoroethylene (PTFE) tubing used in argon‑plasma‑coagulation (APC) probes with biobased polymers. PTFE is prized for its low friction coefficient, flexibility, thermal stability, electrical insulation and biocompatibility, but it cannot be recycled and is incinerated as medical waste, releasing CO₂ and fluorinated hydrocarbons. The estimated global CO₂‑avoidance potential of substituting PTFE in medical devices was 2.6 million tonnes per year. The German Federal Environmental Foundation funded the effort (project number 38549/01‑21/2) and it was carried out from 2021 to 2024 by ERBE Elektromedizin GmbH and Biovox, with Dr. Sascha Dammeier and Vinzenz Nienhaus as authors.
The technical work focused on identifying a polymer that could match PTFE’s mechanical, electrical and biocompatibility properties while offering a much lower cradle‑to‑gate CO₂ footprint. Two biobased candidates were selected: polylactide (PLA) with a footprint of about 0.6 kg CO₂e kg⁻¹ and polyethylene (PE) with 2.1 kg CO₂e kg⁻¹. PTFE’s tensile modulus ranges from 400 to 800 N mm⁻², whereas unmodified PLA is far stiffer at 3600 N mm⁻², making it unsuitable without modification. A novel copolymer of PLA and a soft phase was therefore developed, and the material was fractionated to obtain a usable additive fraction. The copolymer achieved an elongation at break of 100 % and superior resilience compared with PLA compounded with conventional plasticisers, but only limited amounts were available for testing.
Extensive mechanical testing was performed. Tensile tests on PLA‑based specimens, both compounded and extruded, failed to meet the required bending properties. Extruded PE tubes, even when plasticised, did not provide the necessary flexibility. High‑voltage tests on extruded PE and cross‑linked PE (XPE) tubes, as well as on the newly designed APC electrode, were conducted to assess electrical insulation. While the tests confirmed that the electrode concept could tolerate lower‑insulation tubes, the overall performance did not yet satisfy all clinical requirements.
The project therefore shifted focus to a new electrode architecture that could be paired with tubes of reduced electrical isolation. This approach preserved the mechanical and biocompatibility advantages of the biobased polymers while transferring the stringent electrical demands to a separate component. The resulting design was presented at major medical trade fairs such as MEDICA, COMPAMED, MEDTEC and the American Clinical Conference (ACC), highlighting its potential to encourage other manufacturers to replace PTFE.
In conclusion, the research demonstrated that biobased polymers can meet the essential mechanical and biocompatibility criteria for APC probes, but further development is needed to improve their mechanical performance for clinical use. ERBE and Biovox plan to continue refining the concept, focusing on biobased cross‑linked polyethylene (XPE) and the novel electrode design, with the goal of offering fully biobased APC probes in the medium term. The collaboration, supported by the German Federal Environmental Foundation, has laid the groundwork for a more sustainable medical device industry.