Fig. 3. Biochemical sensors for biomarker detection in saliva.

a Fabrication of immune electrodes for saliva-based oral cancer detection⁸. b A mouthguard sensor integrated with a wireless module and battery; the schematic (bottom) shows that the glucose sensor consists of an anti-interference membrane and an enzyme membrane on Pt and Ag/AgCl electrodes⁵⁴. c Organic electrochemical transistor (OECT) based on platinum nanoparticles modified with glucose oxidase and polyvinyl alcohol (PVA) for a highly sensitive, portable glucose biosensor⁵⁶. d Determination of cholesterol in saliva by platinum nanocluster chemical sensors. The device catalyzes the reaction of cholesterol in saliva by cholesterol enzymes to produce hydrogen peroxide and measures the concentration of cholesterol by measuring the concentration of hydrogen peroxide⁵⁸. Calibration curve of the Pt-NC/enzyme/Nafion sensor showing the current response to the continuous addition of total cholesterol under continuous stirring in 0.1 M PBS buffer⁵⁸