Flexible chemiresistive sensor with xurographically patterned gold leaf as contact electrodes for measuring free chlorine

Carbon‐Based Electrochemical‐Free Chlorine Sensors

“…[46] Chemiresistors are two-terminal devices made of source and drain contacts with the channel/transducing material as the sensitive material [Figure 10a] and have a constant applied potential (or current) between them when used to detect free chlorine. [41,[78][79][80][81] The sensing material has an intrinsic electrical resistance/conductance, which will change accordingly upon exposure to solutions with different free chlorine concentrations. This can be irreversible such as the resistance of a nanohybrid chemiresistor [81] or it can be reversible such as carbon-based materials functionalized with phenyl-capped polyaniline tetrameter (PCAT) [82] where the resulting current (or potential) signal [69] Copyright 2015, Elsevier.…”

“…PCAT, on the other hand, has been used to functionalize CNTs, graphene, graphene-like carbon. [44,[78][79][80]82] The fabrication process and designs of both sensors are simple and reported LODs were as low as 1 ppb. [82] Given the potential of these designs, materials that make use of their simplicity in both design and with compatible readout systems should be explored.…”

“…[ 46 ] The schematic in Figure shows the different types of compounds that have been used to functionalize the carbon‐based materials either through chemical or electrochemical methods. Furthermore, the fabrication methods implemented are limited to ones such as flowing molecules like PCAT through various apparatuses, [ 79,80,82 ] the interfacial method, [ 55 ] or in situ functionalization methods. [ 63,69,106,107 ]…”

“…[46] The schematic in Figure 15 shows the different types of compounds that have been used to functionalize the carbon-based materials either through chemical or electrochemical methods. Furthermore, the fabrication methods implemented are limited to ones such as flowing molecules like PCAT through various apparatuses, [79,80,82] the interfacial method, [55] or in situ functionalization methods. [63,69,106,107] There are two main methods to functionalize graphene: i) covalent functionalization by grafting molecules onto the sp 2 carbons of the graphene plane; and ii) non-covalent functionalization through the adsorption of polycyclic aromatic compounds or hydrophobic interactions on the carbon plane.…”

A reagent-free phosphate chemiresistive sensor using carbon nanotubes functionalized with crystal violet

“…These sensors do not require a reference electrode for measurements. In the past, these sensors have been used for gas sensing 15 and lately they have been used for sensing molecules like glucose, 16 hydrogen peroxide, 16,17 free chlorine 18 and pH 19 in liquid media. 14 Crystal violet is a triphenylamine dye which is commonly used as a paper and textile colouring agent.…”