Fig. 10.

Flexible as well as wearable pH sensors. a Schematic diagram of the sensor structure based on graphene/RuO₂ (Daniel Janczak, Andrzej Peplowski, Grzegorz Wroblewski, Lukasz Gorski, Elzbieta Zwierkowska, and Malgorzata Jakubowska- Investigations of printed flexible pH sensing materials based on graphene platelets and submicron RuO₂ powders, Journal of Sensors (2017)1–7, Copyright © 2017 Daniel Janczak et al. b Flexible PGM based sensor, its pH sensing performance and stability (reproduced with permission from Z. Tehrani1, S.P. Whelan1, A B Mostert, J V Paulin, M Ali1, E. Daghigh Ahmadi1, C F O Graeff, O J Guy and D T Gethin- Printable and flexible graphene pH sensors utilizing thin film melanin for physiological applications, 2D Mater. In (2020),10.1088/2053-1583/ab72d5, https://creativecommons.org/licences/by/3.0