Abstract
This thesis presents a miniature fluidic probe that is capable of self-adapting its shape to teeth and detecting caries at its early stage by sensing the variation in electrical-impedance. The fluidic probe, whose liquid tip spontaneously spreads on hydrophilic tooth surfaces and into underneath caries, is employed to create intimate electrical contact for impedance sensing. A tubular air sleeve shaped by the probe casing is applied around the contact point to insulate it from surrounding saliva, and to regulate the spreading of the liquid tip. In the prototype demonstration, 23 un-restored, extracted premolar teeth were investigated and the results indicated >30 times impedance variations between sound and carious teeth, by which caries could be identified in a sensitive and reliable manner. Furthermore, the fluidic probe has been successfully applied to detect approximal caries, which hides between adjacent teeth and is hardly detected by any existing techniques. As such, the proposed self-adaptive fluidic probe could readily serve as a diagnostic tool, which is critical to caries prevention and home-care applications.