Increase in detection sensitivity of surface acoustic wave biosensor using triple transit echo wave

Abstract

Here, we present a surface acoustic wave (SAW) biosensor for the highly sensitive detection of cardiac troponin I, a gold standard biomarker for the diagnosis of myocardial infarction, using a triple transit echo (TTE) wave of a SAW rather than a conventional main wave. Compared with the main wave, the TTE wave is caused by reflections from output and input interdigitized transducers (IDTs) after traversing the propagation path three times between input and output IDTs. The SAW biosensor using a TTE wave signal showed enhanced sensitivity for measuring the viscosity of glycerol solution and the mass loading effect of immunoassay reaction due to much bigger modulation induced in the amplitude, phase, frequency, and time-delay of the TTE wave. Our results showed that the proposed SAW biosensor could quantitatively analyze cardiac troponin I. Detection limit values using the main wave and the TTE wave were 766 pg/ml and 24.3 pg/ml, respectively. Therefore, one can say that the sensitivity of the SAW biosensor substantially improved when the TTE wave is used. Published by AIP Publishing.