1 Vol.:(0123456789) Scientifc Reports | (2020) 10:17180 | https://doi.org/10.1038/s41598-020-74337-w www.nature.com/scientificreports Textile sensors platform for the selective and simultaneous detection of chloride ion and pH in sweat Luca Possanzini 1* , Francesco Decataldo 1 , Federica Mariani 2 , Isacco Gualandi 2 , Marta Tessarolo 1 , Erika Scavetta 2 & Beatrice Fraboni 1 The development of wearable sensors, in particular fully-textile ones, is one of the most interesting open challenges in bioelectronics. Several and signifcant steps forward have been taken in the last decade in order to achieve a compact, lightweight, cost-efective, and easy to wear platform for healthcare and sport activities real-time monitoring. We have developed a fully textile, multi-thread biosensing platform that can detect diferent bioanalytes simultaneously without interference, and, as an example, we propose it for testing chloride ions (Cl − ) concentration and pH level. The textile sensors are simple threads, based on natural and synthetic fbers, coated with the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) and properly functionalized with either a nano-composite material or a chemical sensitive dye to obtain Cl − and pH selective sensing functionality, respectively. The single-thread sensors show excellent sensitivity, reproducibility, selectivity, long term stability and the ability to work with small volumes of solution. The performance of the developed textile devices is demonstrated both in bufer solution and in artifcial human perspiration to perform on-demand and point-of-care epidermal fuids analysis. The possibility to easily knit or sew the thread sensors into fabrics opens up a new vision for a textile wearable multi-sensing platform achievable in the near future. Wearable sensing technologies are attracting a growing academic and industrial interest thanks to the driving force of market demand and the prospective large impact on real life. Personalized healthcare and point-of-care medical assistance, together with ftness, represent the main felds of applications meeting the highest request for wearable biosensors. Te convergence of technical advancements in complementary research areas is making possible the devel- opment of wearable devices such as: (i) energy-harvesting devices 1–3 , (ii) energy-storage devices 3–5 and (iii) sensors 6,7 . On one hand, wearable physical sensors exhibit a high readiness level and include strain sensors to moni- tor physical movement 8 , motion 9,10 , heartbeat 11 or respiratory rate evaluation 12 and pressure sensors based on memory systems 13 , textile devices 14,15 or skin-based architectures 16 . Moreover, bio-potential sensitive sensors can record skin potential that allows, for example, electrocardiograms 17–19 and electromyography 20 . On the other hand, wearable chemical sensors are at an early stage of development even if they represent a powerful tool to monitor human physiological parameters in a real-time, non-invasive and accurate manner. A number of new chemical sensors are proposed in the literature for the detection of biochemical markers like dopamine 21 , adrenaline 22,23 , cortisol 24 , glucose 25 , lactate 26 , phenolic compounds 27,28 , and electrolytes 29–32 with the aim of providing new tools for monitoring human health, physical exertion, fatigue and mental accuracy. An interesting approach has been proposed by Gao et al. based on a fully integrated and mechanically fexible sensor array for multiplexed sweat analysis, which selectively and simultaneously measures perspiration electrolytes (sodium and potassium ions) and metabolites (glucose and lactate) 33 . A fully textile sensor device 34–39 embod- ies the most advanced technological frontier to achieve complete fexibility, portability, non-invasiveness and lightweight towards continuous human body monitoring. Teir wide spread use, in addition to a well-established OPEN 1 Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy. 2 Department of Industrial Chemistry, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy. * email: luca.possanzini2@unibo.it