Laser-fabricated flexible nanographene-based sensor for pH detection in saliva

Salivary pH is one of the indicators of the dental health of a person. To enable fast and easy dental health observations, we developed a flexible capacitive pH sensor using graphene oxide (GO) sensing layer on the laser-induced graphene (LIG) electrode produced from a polyimide (PI) film acting both as LIG precursor material and substrate. Cyclic voltammetry (CV) was used as a measurement technique. The sensor showed the characteristic CV behavior of capacitive elements, and it presented an unequivocal response to the pH level in saliva. The area under the CV curve was used to extract the specific capacitance (C
_s
) and correlated to the corresponding pH level measured.