An electrochemical immunosensing lab-on-a-chip integrated with latch mechanism for hand operation

This paper presents the development of a hand-operated lab-on-a-chip (LOC) with latch mechanism for portable immunosensing applications. To control the transportation of multiple liquids without any external equipment, a capillary attraction force is used for filling liquid. Hydraulic pressure which is caused by the elastic deformation of the cover caps of the reservoir is used for exchanging liquids in the reaction channel. To prevent unwanted backward flow, the latches of the LOC, which consist of reversed mushroom-shaped elastic cover caps and rigid locking components, are used to retain the internal pressure in the reservoir. The electrochemical immunoassay measuring antibody concentrations are performed within the fabricated LOC to highlight its portability to be used as a diagnostic system. The immunosening mechanism applied to this LOC is the electrochemical signaling from the antigen-antibody interaction with the bioelectrocatalyzed enzymatic signal amplification. The proposed signaling strategy is based on the backfilling method, which does not require any complicated processes such as antibody labeling steps or any labeled secondary antibodies. As a modeling test of the immunoassay, the anti-dinitrophenyl (DNP) antibody with an enzymatic catalysis was selected as the target analyte.