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Evaluation of Carbon-Based Interconnects for Digital Signaling in Printed Flexible Electronics on Sustainable Substrates

Year: 2025
Type: article
Abstract: Printed electronics using flexible substrates are an emerging area, allowing next-generation electronics to conform and flex with different surfaces, from human skin to clothing. In the hybrid integration, or sea-of-rigids, approach, conventional microchips are mounted onto (generally) plastic substrates such as polyethylene naphthalate (PEN), with (typically) printed silver tracks for interconnections between components. An ongoing research direction is to replace plastic substrates with biodegradable substrates and to replace silver tracks with non-heavy metal-based tracks. While the substrates and tracks form only part of an overall system, replacing them is a step towards increased sustainability and helps to meet net-zero goals for printed electronic systems. Previously, several papers have investigated printed carbon tracks for low-frequency analog sensing applications. This paper explores the feasibility of using printed carbon tracks on biodegradable substrates for high-frequency applications such as digital signaling over a Serial-Peripheral Interface (SPI). We investigate the printability, thermal stability, and electrical conductivity of carbon ink screen-printed onto six commercially available sustainable and flexible substrates. Our results demonstrate that multi-layer screen printing substantially reduced the electrical resistance of carbon tracks, enabling SPI communication at frequencies up to 16 MHz with three layers of carbon ink. A Natureflex™ substrate provided the best balance of printability, thermal stability, and electrical performance. Substrates such as greaseproof paper and ClearFilm PU showed potential for flexible electronics, but require further optimization. This study provides valuable insights into selecting and optimizing biodegradable substrates for high-frequency digital systems, supporting the move towards more sustainable printed electronics.
DOI: 10.1109/jflex.2025.3562530
Authors: Zixin Wang, Mahdi Saleh, Aula Alwattar, Maria Alfredsson, Robert J. Horne, Chee S. Ang, Joan Condell, Emily Flowers, Faith Matcham, Tony Robinson, John Rooksby, Sian Saha, Louise Rose, John C. Batchelor, Alexander J. Casson
Institutions: Henry Royce Institute, University of Manchester, University of Kent, University of Ulster, Ulster University, Derry-Londonderry Campus, King's College London, University of Sussex, Northumbria University
Language: English
Open Access status: green
Awards: G1015058392, G3305536412, Sir Henry Royce Institute - Manchester and NNL Equipment, G4630886971, G504327055, G5424142534, Sir Henry Royce Institute - Manchester Build, MultiSense - Devising and Manufacturing mm-Wave High Data Rate Low Latency On-Skin Technologies, G708391930, Unpacking the black box of interventions such as peer support designed to optimize mental health outcomes of family caregivers, G7445816383, G7514479249, Sir Henry Royce InsStitute - recurrent grant, G87373762
OpenAlex ID: W4410086335
FWCI: 0.455
Cites: 36
Cited by: 2
Related to: 10