Novel label-free capacitive sensor based on interdigitated electrode arrays for multiplex point-of-care testing

In the current study interdigitated electrodes (IDE) consist of two arrays of electrodes with comb shape were utilised. Interdigitated electrode arrays containing nine IDE were fabricated with conventional microelectronics-micromachining technologies on standard glass slides in a class 1000 clean room. The Au electrode surfaces were first modified with an alkanethiol monolayer and glass slide was modified with a blocking silane to prevent non-specific binding. Capacitance measurements were taken using a 41R LCR meter (CHY Firemate C., Taiwan) that was connected to the computer to record the capacitance results every 10 seconds to obtain a continues assay trace (Figure 1). Initially an antibody against prostate specific antigen (PSA) as a cancer biomarker was immobilised on to the IDE surface; antigen binding assays were then developed to capture the PSA molecule achieving a clinically significant concentrations. This study clearly demonstrates the potential use of the label-free capacitance sensor platform for point of care testing. Further developments are underway to optimise the system using the necessary electronic detection units. This work will be presented in this paper looking at possible analysis of a range of other disease biomarkers.