SENSITIVITY OF NOVEL ULTRATHIN PLATINUM FILM IMMUNOSENSORS TO BUFFER IONIC-STRENGTH

The direct detection of antibody/antigen binding is demonstrated with a conductivity-based sensor. The sensor consists of an ultrathin Nm of platinum 25 Angstrom thick deposited onto an insulating silicon dioxi de or silicon nitride substrate. The film has a metal island structure , as demonstrated by atomic force microscope images of the surface. Th e impedance response at 20 Hz to 1 MHz measured in buffers of differin g pH and ionic strength indicates that the conductivity of the solutio n is a dominant factor in defining the response of the sensor.