Cholinium-based iongels for bioelectronic applications

LUQUE, GISELA C.; AGUZIN, ANA; GUGLIOTTA, LUIS M.; MECERREYES, D.; MINARI, R.J.

Praga

Congreso; EPF European Polymer Congress; 2022

European Polymer Federation

Currently bioelectronics area is looking for new soft-ionic systems to the interface between biology and electronics, with the aim to improve the performance in recording signals across this interface.1 In this scenario iongels (IGs) presented themself like excellent candidates due to the ionic conductivity, self-healing, thermo-responsiveness or biocompatibility.2,3 Unlike hydrogels, IGs have the capability to maintain the ionic conductivity values over time, allowing an excellent performance for the signal recordings. In this work, we report the preparation of iongel formed with two different polymer matrix (poly(vinyl) alcohol (PVA) and gelatin), phenolics compounds (PhCs) as crosslinkers, and cholinium based ionic liquids (ILs). In terms of synthesis, the same simple dissolution/evaporation method was employed to synthesize the IGs, but in gelatin case the mixture was maintained one hour at 90°C in order to assure the formation of covalent bonding between gelatin and tannic acid. In all cases polymer concentration was varied between 5 and 20%. Iongels were characterized in terms of their thermal (TGA), mechanical (compression test) and rheological (DMTA) properties. Also, ionic conductivity (IC) was measured. In all cases the IGs were elastics with Young modulus between 14 and 70 kPa, the PVA based IGs have thermoreversible properties with gel–sol transitions ranging from 85 to 110 °C, which allows the iongel processing via direct ink writing 3D printing by material extrusion at temperatures over its transition. Furthermore, excellent and stable IC values were registered between 25 and 60°C (around 10–2 S cm–1). Finally, in order to analyze the performance of the IGs in the bioelectronic area, they were tested in different body sensor devices such as electrocardiogram (ECG), electromyography (EMG), and as pressure sensor layers to detect human motion.