Fabrication and testing of a PDMS multi-stacked hand-operated LOC for use in portable immunosensing systems.

This paper presents the development of a reliable multi-liquid lab-on-a-chip (LOC), with a hand-operated mechanism, for the application in portable immunosensing systems. To control the transport of multiple liquids without any external equipment, we utilize capillary attraction force for filling and surface tension for stopping liquid flow. As a driving force, hydraulic pressure caused by the elastic deformation of a liquid reservoir transfers liquid stopped at passive valves. The proposed LOC successfully demonstrates a reliable sequential liquid transfer within the reaction channel. To highlight its feasibility as a portable diagnostic system, we performed the electrochemical immunoassay measuring antibody concentrations within the fabricated LOC. As a test biorecognition reaction, the anti-dinitrophenyl (DNP) antibody with an enzymatic catalysis was selected as the target analyte. The amplified signals obtained from this experiment indicated a high selectivity of the immunosensing LOC.