Stretchable Electrodes Using Conductive Polymers for the Detection of Vital Signs in Premature Infants

Monitoring vital signs of prematurely born children is of utmost importance for their health. The measurements of electrophysiological signals require the placement of electrodes on the skin via an adhesive, which can cause damage as premature ski n lacks a protective outer layer. Therefore, alternative monitoring methods are needed to increase comfort and reduce the burden on premature infants. This can be achieved with flexible and stretchable electrodes that can adapt to the shape and movements of the child while maintaining signal quality. To date, a few studies on hydrogel-based electrodes with excellent mechanical and electrical properties have been reported. However, their water content makes them prone to degradation from evaporation, and the refore unsuitable for long term monitoring. This study focuse d on the development and characterization of a dry, printable, stretchable, lightly adhesive, and self -healing material suitable for biomedical electrodes for premature infants. This research lev eraged the favorable characteristics of poly(3,4 -ethylenedioxithiopene) doped with polystyrene sulfonate (PEDOT:PSS), a conductive material with tun able electrical and mechanical properties depending on the used additives. In this work, we explored the incorporation of polyurethane diol (PUD), polyethylene glycol (PEG), and sorbitol as additives to PEDOT:PSS to develop an optimized printable mixture. As these combinations significantly enhance both the mechanical and electrical properties of PEDOT:PSS, we evaluated these properties on an electromechanical tester. We also quantified their adhesion on different substrates to evaluate their suitability for epidermal electrodes. Moreover, to verify the material’s safety for skin application, we assessed its biocompatibility. In addition, we demonstrated the full electrical self-healing properties of PUD/PEDOT:PSS. The potential biomedical application of this material was further demonstrated through the fabrication of a printed epidermal electrode on a stretchabl e silicone substrate. The resulting electrodes display ed skin-electrode impedance comparable to that of a commercially available alternative and successfully capture d physiological signals , including electrocardiogram (E CG) and electromyogram (EMG) signals. PUD, the final additive combined with PEDOT:PSS and used for the fabrication of the printing ink, played a key role in the mechanical and electrical, adhesion and self-healing properties of the material.