IMMUNOSENSING WITH SURFACE-ACOUSTIC-WAVE SENSORS

In this paper we present the utilization of horizontally polarized sur face acoustic waves for immunosensing in liquids. We have used a dual- delay-line device on an LiTaO3 substrate working at 345 MHz to detect immunoglobulins of type G in phosphate buffer. The measurements are pe rformed either using a 'droplet technique' with small amounts(5 mu l) of liquid, or in a flow-through cell. From the experimental results we derive a sensitivity of 112.5 kHz (ng mm(-2))(-1) and a detection lim it of 35 pg for the absolute mass. We find a quadratic frequency depen dence of the sensor signal, indicating a mass-loading effect. (C) 1997 Elsevier Science S.A.