Sericin Electrodes for biodegradable healthcare devices

The rapid advancement in medical technology has led to an increased reliance on disposable medical devices in clinical settings., including medical electrodes. While these devices play a crucial role in patient diagnostics and treatment, their extensive use has raised concerns regarding the environmental impact of materials they are composed of. Medical electrodes (MC) are commonly used in bio-signals monitoring, such as electrocardiography (ECG), electroencephalography (EEG), and electromyography (EMG). Their design incorporates materials for enhancing electrical conductivity, flexibility, and biocompatibility, making them suitable for accurate medical data acquisition. However, the disposal of MC can be challenging because of the different materials, including plastics, adhesives, metals, and conductive gels. Improper disposal practices can lead to the release of hazardous substances into the environment, posing risks to ecosystems and human health 1.  This research contribution focuses on the use of silk sericin to create an innovative biodegradable electrode for the monitoring of bio-signals. Silk sericin is a glycoproteic compound it constitutes a significant portion of natural silk and has been treated as a by-product in silk manufacturing. Recently sericin showed some intriguing and easily tuneable properties2. We show here a three-layered device, wherein the first layer consists of a sericin film acting as an adhesive layer and ion reservoir. Through an autoclaving process, sericin is extracted, mixed with a mechanical properties enhancer (polyvinyl alcohol PVA), and allowed to evaporate, the output resulting in a standalone film. The sericin film exhibits self-adhesive properties thanks to to the addition of hygroscopic salts, enhancing adhesion to the skin for long-term signal acquisitions. The second layer incorporates PEDOT:PSS as an organic conductive element, that allows us to circumvent traditional metallic materials to reduce waste. Organic semiconductors such as PEDOT:PSS offers conductivity and impedance-adapting properties. The PEDOT:PSS layer is printed through additive manufacturing techniques, specifically by aerosol jet printing. Finally, the third layer is required as a protective barrier composed of bacterial cellulose. The sericin electrode shows an impedance lower than commercial electrodes, measuring down to 10-4 Ω showcasing their efficacy in bio-signal monitoring. We appley sericin electrode for a real-time ECG acquisition, achieving comparable signals of commercial electrodes. This innovative approach addresses the environmental concerns associated with traditional electrodes and offer a tool for sustainable and biodegradable medical devices in the field of healthcare. 1. G. Tarabella, D. Vurro . et al. Aerosol jet printing of PEDOT:PSS for large area flexible electronics. Flex. Print. Electron. 5, 014005 (2020). 2. Liu, J. et al. Silk sericin-based materials for biomedical applications. Biomaterials 287, 121638 (2022).