Fig. 3.

Electrochemical based pH sensors. (A) A pH-sensitive bandage fabricated from PANI and Ag/AgCl electrodes [34]. (B) A PANI coated nanopillar array for enhancing the sensor's sensitivity [61]. (C) An integrated wearable pH sensor patterned on a flexible PET substrate and used for real-time monitoring of sweat pH during human activities [62]. (D) A high stretchable serpentine like pH sensor fabricated using laser carbonization of PANI [63]. (E)The fabrication process of the omniphobic paper-based smart bandages (OPSB) [64]. (F)An automated smart bandage for pH sensing and antibiotic drug release [65]. (G) In vivo transdermal pH sensing with microneedles electrodes [36]. (H) Details of the fabrication procedure of the cotton yarn-based band-aid [66]. (I) A toolkit of thread-based chemical and physical sensors, microfluidic channels, and interconnects for the realization of a thread-based diagnostic device [67].

(Reproduced from Refs. [34,36,[61], [62], [63], [64], [65], [66], [67]] with permissions from Wiley online library, Elsevier, ACS publications, pubs.rsc.org and Nature).