Electrical interface design for additively manufactured polymer anodes for biophotovoltaic systems

Reliable electrical interfacing between additively manufactured conductive polymer anodes and external circuits remains a key challenge in biophotovoltaic (BPV) systems, particularly due to debonding failures during operation. This study aims to identify interface configurations that enhance mechanical stability and electrical performance while maintaining biocompatibility, thereby improving device reliability.

A comprehensive evaluation was conducted on multiple electrical connection strategies for inkjet-printed poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) anodes. Mechanical connection approaches tested included tantalum wire clips, terminal block connectors, crocodile clips, and carbon tapes. In parallel, conductive adhesive materials-silver conductive paint, electric paint, and carbon cement adhesive-were assessed. Each interface was systematically evaluated for mechanical durability, electrical resistance, and biocompatibility in a water-based growth medium. Protective coatings were also applied to selected adhesive interfaces to improve performance.

The findings show that mechanical connection methods are unsuitable for inkjet-printed PEDOT:PSS anodes, as they can damage the polymer film and are prone to corrosion. In contrast, adhesive-based interfaces demonstrated improved compatibility but required protective coatings to enhance durability. Among the tested materials, silver conductive paint coated with epoxy resin showed the best performance, achieving 100% stability in aqueous medium over 7 days. Transparent silicone resin coatings provided moderate improvement, achieving 33.4% stability. Overall, the optimized configurations reduced in-operation debonding failure from 66% to less than 1%.

These results highlight the critical role of interface selection and protection strategies in improving the longevity and performance of BPV systems. Adhesive-based electrical interfaces, when combined with appropriate protective coatings, offer a viable solution for maintaining stable connections with delicate conductive polymer anodes. The framework established in this study provides a systematic basis for assessing electrical interface materials, contributing to the optimization of electrode connectivity and overall device efficiency in BPV applications.